1175 lines
103 KiB
Plaintext
1175 lines
103 KiB
Plaintext
*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*
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* *
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* RWTSDRV1 using FORMAT *
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* *
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*----------------------------------------------------------------*
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* *
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* Just as the file manager is used to manipulate entire *
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* files at once, RWTS reads or writes disk data one sector at a *
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* time. The software interface between these two levels of DOS *
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* management is represented by the RWTS driver routines *
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* (RWTSDRVR, $B052 and RWTSDRV1, $B058). RWTSDRVR is called any *
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* time the file manager wants to seek a given track or read or *
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* write a sector of disk data. This routine is always entered *
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* with the accumulator containing the RWTS opcode ($00=seek, *
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* $01=read, $03=write) and the x- and y-registers housing the *
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* target track and sector values. Although RWTSDRV1 is only *
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* directly called via the INIT function handler (with the *
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* accumulator containing the format ($04) opcode), execution *
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* falls into RWTSDRV1 from RWTSDRVR. The driver routines check *
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* to see if data are to be output to the disk and condition the *
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* carry flag accordingly. The carry is set if the format or *
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* write opcodes are detected. After setting up RWTS's parameter *
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* list (also known as an input/output block, IOB), the driver *
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* calls ENTERWTS ($B7B5). *
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* ENTERWTS preserves the conditioned carry flag by pushing *
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* the status register on the stack. Next the interrupt disable *
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* flag is set to prevent any maskable interrupts from interfer- *
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* ring with the real-time subroutines employed by RWTS. *
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* Finally, ENTERWTS calls RWTS proper ($BD00) to do the desired *
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* function. *
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* Actual formatting of the disk occurs in the FRMNXTRK *
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* routine ($BED4). Formatting begins with track 0 and ends with *
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* track 34 ($22). However, the "CMP #$23" instruction at $BEFD *
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* can be changed ("CMP #$24") to accomodate an extra track if *
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* the drive has been appropriately adjusted. Each track is *
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* formatted with 16 sectors ($00-$0F). Sector 0 is always *
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* created first and is preceeded by 128 self-sync bytes (gap 1). *
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* The WRITADR ($BC56) routine is responsible for checking *
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* the write-protect switch, writing a series of self-sync bytes *
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* (gaps 1 and 3) and then creating the address header. The *
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* address header consists of 14 bytes. A three-byte prologue *
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* ("D5 AA 96") is followed by odd-even encoded bytes describing *
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* the volume, track and sector numbers and an address checksum. *
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* The address field is terrminated by a three-byte epilogue *
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* ("DE AA EB"). *
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* The WRITESEC routine ($B82A) writes a five-sync space *
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* (gap 2) between the address epilogue and data prologue *
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* ("D5 AA AD"). Three hundred and forty-two 6-and-2-encoded *
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* disk data bytes (256 memory bytes) follow the prologue. When *
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* formatting, all data bytes are zeroed out. (That is, "$00" *
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* memory bytes are converted to "$96" disk bytes.) The data *
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* bytes are followed by the data epilogue ("DE AA EB"). (All *
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* data and address bytes are written in a 32-machine cycle *
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* format. The self-sync bytes however are represented by *
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* 40-cycle $FF's made up of ten-bit bytes.) The actual number *
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* of self-sync bytes that make up a gap is not consistent *
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* because drive speeds vary and new data sectors can overlap *
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* previous gaps. (See Chapter 3 of BENEATH APPLE DOS for an *
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* explaination of self-sync bytes and encoding structures.) *
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* After each track is written, it is read to verify the *
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* integrity of the disk bytes. Several attempts at verification *
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* are made before an I/O error message is generated. Once *
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* verification is complete, the track is re-read until sector 0 *
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* is encountered. This extra read presumably adjusts the timing *
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* so that like-numbered sectors in neighbouring tracks are *
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* kept somewhat adjacent. *
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* Execution eventually returns to the ENTERWTS routine at *
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* $B7BA (via DONEFRMT , $BF09). After the saved status byte is *
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* pulled off the stack, the carry flag is cleared or set *
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* depending on whether or not RWTS encountered an error. *
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* Execution then returns to the caller of ENTERWTS. *
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* After updating the last-used volume value in the FM *
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* parameter list, the RWTSDRV1 routine checks the carry flag to *
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* see if RWTS detected an error. If an error was encountered, *
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* the carry is reset and execution returns to the calling *
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* routine via ERRWTSDR ($B0A1). If no error was detected, the *
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* "BCS ERRWTSDR" instruction at $B09E is skipped and execution *
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* returns to the caller of the driving routine with the carry *
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* clear. *
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* Note that ENTERWTS is the one and only DIRECT caller of *
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* RWTS. THE DOS MANUAL recommends the following procedure be *
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* employed to call RWTS from an assembly language program: *
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* 1) Set up the IOB and DCT tables accordingly. *
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* 2) Load the y-register and accumulator with the low and *
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* high bytes (respectively) of the address of the IOB. *
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* 3) JSR to $3D9. (The instruction at $3D9 normally *
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* contains a jump to ENTERWTS.) *
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* The execution pattern of RWTS and its associated sub- *
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* routines is long, but not particularly complex. On the one *
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* hand RWTS is rather simple because it can only perform four *
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* types of functions (seek, read, write or format). However, *
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* many people find RWTS difficult to understand because: *
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* 1) It is the only portion of DOS that uses time-critical *
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* code. *
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* 2) Two different methods are used to encode information *
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* on the disk. *
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* 3) The actual method by which the read/write head is *
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* moved to different track positions on the disk is not *
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* well publicized. *
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* Time-critical code and data encoding information are only *
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* briefly described below. However, these concepts are clearly *
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* explained in chapter 3 of BENEATH APPLE DOS. (When reading *
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* this reference, you may find it elcudiating to keep in mind *
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* that some protected disks (such as LOCKSMITH by ALPHA LOGIC *
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* BUSINESS SYSTEMS) modify the read/write routines to EOR each *
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* sector of data with its sector number.) *
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* The positioning of the read/write head is the sole *
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* responsibility of the SEEKIT routine ($BE6B). This routine is *
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* highly commented in the disassembly given below. The follow- *
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* ing comments are applicable to the SEEKIT routine and RWTS in *
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* general: *
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* - Data are written on the disk in 35 circular paths or *
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* concentric circles called tracks. Track $00 is located at *
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* the outer edge of the disk, whereas track $22 (#34) is *
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* represented by the innermost concentric circle. Each track *
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* is divided into 16 segments ($00 to $0F) called sectors. *
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* - A disk controller card can be used in any peripheral slot *
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* except slot $00. Each of the remaining seven slots ($01 to *
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* $07) can contain a controller card. Two different drives *
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* can be operated from one controller card. Therefore, you *
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* can hang up to 14 different drives from a single Apple II, *
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* II+ or IIe machine. *
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* - The disk controller ROM is relocatable and is copied into *
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* the computer's memory at $Cs00 to $CsFF (where s = slot *
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* number). All drive functions are performed by indirectly *
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* referencing base addrs $C000 to $C00F. The motor-on-off, *
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* drive selection and read-write switches are indexed with an *
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* offset equal to slot * 16. The four different stepper motor *
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* magnets are all referenced via the $C080 base addr. The *
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* index used = (slot*16) + lower 2 bits of halftrk # + carry. *
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* The slot & bit portions of the index are used to select the *
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* desired magnet. The added carry is used to make the *
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* effective addr even or odd in order to turn the magnet off *
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* or on. The EFFECTIVE addresses for all drive functions are *
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* shown below: *
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* MAG0FF = $C0s0 ;Turn stepper motor magnet 0 off. *
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* MAG0N = $C0s1 ;Turn stepper motor magnet 0 on. *
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* MAG1OFF = $C0s2 ;Turn stepper motor magnet 1 off. *
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* MAG1ON = $C0s3 ;Turn stepper motor magnet 1 on. *
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* MAG2OFF = $C0s4 ;Turn stepper motor magnet 2 off. *
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* MAG2ON = $C0s5 ;Turn stepper motor magnet 2 on. *
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* MAG3OFF = $C0s6 ;Turn stepper motor magnet 3 off. *
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* MAG3ON = $C0s7 ;Turn stepper motor magnet 3 on. *
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* MTR0FF = $C0s8 ;Wake up controller and spin disk. *
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* ;This switch must be thrown before a *
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* ;specific drive (1 or 2) is selected. *
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* MTR0N = $C0s9 ;Turn disk drive motor off. *
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* SELDRV1 = $C0sA ;Select drive number 1. *
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* SELDRV2 = $C0sB ;Select drive number 2. *
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* The following addresses are used to read or write data *
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* bytes or to check the status of the write protect switch. *
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* As shown below, they are always used in specific combinations *
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* to evoke a certain range of responses from the controller *
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* card. The firmware affected on the controller card is called *
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* a logic state sequencer. It is a nibble-based language that *
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* only contains six different instructions and is transparent to *
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* the monitor ROM disassembler. (See UNDERSTANDING THE APPLE II *
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* by Jim Sather for further explaination.) *
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* Q6L = $C0sC ;Shift byte in or out of data latch. *
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* Q6H = $C0sD ;Load latch from data bus. *
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* Q7L = $C0sE ;Prepare to read. *
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* Q7H = $C0sF ;Prepare to write. *
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* When used in combinations: *
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* Q7L plus Q6L = select read sequence and then read a byte. *
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* Q6H plus Q7L = check write protect switch and select write *
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* sequence. *
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* Q7H plus Q6H = select write sequence and load data register *
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* with output byte. *
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* Q6H plus Q6L = load latch from data bus and write byte. *
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* (Must have previously selected Q7H.) *
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* - Each disk drive contains two motors. One motor (usually *
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* referred to as the "drive motor") spins the disk at a *
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* constant speed. (When the drive motor is first turned on, a *
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* delay is used to wait for the drive to come up to speed *
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* before attempting to read or write disk bytes.) Another *
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* motor (called a "stepper motor") moves the read/write head *
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* across the disk to position the head at different track *
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* positions. *
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* - The stepper motor can be envisioned as containing a central *
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* magnet on a rotatable shaft and a circle of four fixed *
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* magnets (magnets 0 to 3) surrounding the shaft. Each time a *
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* peripheral magnet is enegized, the central shaft is rotated *
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* until its magnet is in line with the energized peripheral *
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* magnet. By turning the fixed peripheral magnets on and off *
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* in sequence, we can spin the shaft of the stepper motor. *
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* Movement of this shaft causes the read/write head to "step" *
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* across the disk. Each time the next magnet in sequence is *
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* turned on, the shaft is rotated one quarter turn. One *
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* quarter turn of the shaft moves the read/write head half a *
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* track width. *
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* - Normally, DOS only writes data at even magnet positions *
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* because the drive head does not have good enough resolution *
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* to distinguish information in adjacent half-track positions. *
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* The drive head is stepped to a higher track position as the *
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* magnets are turned on and off in ascending order. *
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* Similarly, a descending reference to the magnets causes *
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* movement to a lower track position. Each time a magnet is *
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* turned on or off, a delay is used to give the shaft magnet *
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* time to properly align with a peripheral magnet. The amount *
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* of delay used is inversely proportional to the acceleration *
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* of the motor. An example of the on/delay/off sequence used *
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* to step the head from track $02 to track $04 is shown below: *
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* 1on - delay - 0off - delay - 2on - delay - 1off - delay - *
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* 3on - delay - 2off - delay - 0on - delay - 3off - delay - *
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* 0off - delay. *
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* Similarly, moving the head from track $04 to track $02 *
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* requires the following sequence: *
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* 3on - delay - 0off - delay - 2on - delay - 3off - delay - *
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* 1on - delay - 2off - delay - 0on - delay - 1off - delay - *
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* 0off. *
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* Note that the last-energized magnet is always turned off. *
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* This is done as a safety measure because magnet-1-on is *
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* hard wired into the write protect switch. (The boot process *
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* is an exception to this rule. The controller ROM leaves *
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* magnet0 energized.) *
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* - Some protected programs modify DOS to skip entire tracks or *
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* write data at odd-numbered magnet positions. However, *
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* because the controller ROM always uses track $00 and because *
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* crosstalk occurs when data is less than one full track width *
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* apart, the data is actually written on a half-track disk at *
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* the following track positions: 0, 1+1/2, 2+1/2, 3+1/2, ..., *
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* 31+1/2, 32+1/2, 33+1/2. For instance, if you wanted to move *
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* the head from track $02 to track $04+1/2, you could add the *
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* following sequence to that described above: *
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* - delay - 1on - delay - 0off - 1 off -delay. *
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* - Data can even be written on quarter track positions (that *
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* is, tracks 0, 1+1/4, 2+1/4, ..., 31+1/4, 32+1/4, 33+1/4) by *
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* turning on two adjacent magnets almost simultaneously in *
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* order to position the head between the two magnets. For *
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* instance, if you wanted to move from track $02 to track *
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* $04+1/4, you could patch DOS to automatically add the *
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* following instructions to the normal sequence described *
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* above: - 1on - no delay - 0on - very short delay - 1off - *
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* no delay - 0off - delay. *
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* *
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*::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*
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(B058)
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RWTSDRV1 STA IBCMD ;Enter with (a) = opcode for RWTS.
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;RWTSDRV1 is the entry point used by the
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;Init function handler.
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(B05B) CMP #2 ;Is cmd a write?
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(B05D) BNE SKPWRSET ;NO, so branch. Note: "CMP" conditions:
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; (c)=0 if seek ($00) or read ($01).
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; (c)=1 if write ($02) or format ($03).
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(B05F) ORA UPDATFLG ;Condition UPDATFLG to designate that
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(B062) STA UPDATFLG ;last operation was a write for next
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;time around.
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* Finish setting up RWTS's
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* input/output block (IOB).
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(B065)
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SKPWRSET LDA VOLWA ;Put complimented vol in IOB.
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EOR #$FF
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STA IBVOL
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LDA SLOT16WA ;Put slot*16 in IOB.
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STA IBSLOT
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LDA DRVWA ;Put drive in IOB.
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STA IBDRVN
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LDA SECSIZWA ;Put sector length in IOB
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STA IBSECSZ ;(standard size of dec. 256
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LDA SECSIZWA+1 ;or hex $0100 bytes).
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STA IBSECSZ+1
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LDA #1 ;ALWAYS designate table type as 1.
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STA IBTYPE
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LDY ADRIOB ;Set (y) & (a) to point
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LDA ADRIOB+1 ;at RWTS's IOB.
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(B090) JSR ENTERWTS ;Go call RWTS.
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* Route execution to RWTS.
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* (Normal entry route to RWTS for custom
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* assembly language programs. See preamble
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* for required entry conditions.)
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(B7B5)
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ENTERWTS PHP ;Save status reg (with conditioned carry) on stk.
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;(c) = 0 if doing seek ($00) or read ($01).
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;(c) = 1 if doing write ($02) or format ($03).
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(B7B6) SEI ;Set interrupt disable flag to prevent
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(B7B7) JSR RWTS ;any further maskable interrupts
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;when doing real-time programming.
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* Read/Write Track/Sector (RWTS).
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* Enter with (y)/(a) pointing at
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* RWTS's input/output block (IOB).
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(BD00)
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RWTS STY PTR2IOB ;Set up a zero page
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STA PTR2IOB+1 ;pointer to RWTS's IOB.
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LDY #2 ;Initialize cntr for max of 2 recalibs.
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STY RECLBCNT
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LDY #4 ;Initialize cntr for # or re-seeks betwn recalibs.
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STY RSEEKCNT
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LDY #1 ;Get slot*16 from IOB & put it
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LDA (PTR2IOB),Y ;in (x) so can use it to index
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(BD12) TAX ;base addresses for drive functions.
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* Check if wanted slot*16 = last slot*16.
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(BD13) LDY #15 ;Index to get val of last slot used.
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CMP (PTR2IOB),Y ;Compare wanted vs last.
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(BD17) BEQ SAMESLOT ;Take branch if using same slot.
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* Want to use different slot so reset (x)
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* back to index old slot so can test old motor.
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(BD19) TXA ;Save slot*16 wanted on stk.
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PHA
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LDA (PTR2IOB),Y ;Get old slot*16 back and
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TAX ;stick it in (x) to index base addrs.
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PLA ;Get slot*16 wanted into (a) from stk
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PHA ;and keep it saved on stk.
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(BD20) STA (PTR2IOB),Y ;Update last-used slot*16 for next time.
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* Check to see if last-used drive assoc with last-
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* used slot is still spinning. If it is, wait for
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* it to stop.
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(BD22) LDA Q7L,X ;Prep latch for input.
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CKSPIN LDY #8 ;Set cntr to insure at least 8 chks.
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LDA Q6L,X ;Strobe latch to read.
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CHKCHNG CMP Q6L,X ;Read again & cmp to last read.
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BNE CKSPIN ;Data changed, so still spinning.
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DEY ;No change, so chk with some
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(BD30) BNE CHKCHNG ;delays just to make sure.
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* Get index for slot wanted.
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(BD32) PLA ;Get slot*16 back off stk
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(BD33) TAX ;and put it in (x).
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* Chk to see if a drive assoc with slot wanted
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* is still spinning. (As soon as get a change then
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* know it's spinning. If no change, chk at least
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* 8 times to be certain it is off.)
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(BD34)
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SAMESLOT LDA Q7L,X ;Set read mode.
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LDA Q6L,X ;Strobe latch to read.
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LDY #8 ;Set cntr for 8 chks if needed.
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STRBAGN LDA Q6L,X ;Strobe latch again.
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PHA ;Delay 14 machine cycles.
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PLA
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PHA
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PLA
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STX SLOTPG5 ;Save slot*16 wanted in page 5.
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CMP Q6L,X ;Has data changed yet?
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BNE DONETEST ;Yes - data changed, so disk spinning.
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DEY ;No - no change, see if chkd enough times.
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BNE STRBAGN ;Chk at least 8 times.
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DONETEST PHP ;Save test results on stk so can later
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(BD4E) ;chk if need extra delay or not.
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* Turn motor on in a drive assoc with slot wanted
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* (just in case it wasn't already spinning).
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* Note: This uses drive with same # as last
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* drive used. This may or may not be the
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* specific drive # we want. However, we must use
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* this instruction to send power via the controller.
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* Once this switch is thrown, we can later re-route
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* that power to whichever drive we want by throwing
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* another switch to select drive1 or drive2.
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(BD4F) LDA MTRON,X ;Turn motor on.
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* Establish z-page pointers to device characteristic
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* table (DCT) and RWTS's I/O buffer (so can use z-page
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* indirect addressing modes).
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* IBDCTP ---> PTR2DCT (3C,3D)
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* IBBUFP ---> PTR2BUF (3E,3F)
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(BD52) LDY #6 ;Get ptrs from RWTS's IOB
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MOVPTRS LDA (PTR2IOB),Y ;and put them in z-page.
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(BD56) STA: PTR2DCT-6,Y ;(Note: ":" used to force
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;a 3-byte instruction.)
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(BD59) INY
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CPY #10 ;4 bytes to copy (6 to 9).
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(BD5C) BNE MOVPTRS
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* Check drive status.
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(BD5E) LDY #3 ;Save hi byte of motor-on-time
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LDA (PTR2DCT),Y ;count in z-page.
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STA MTRTIME+1
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LDY #2 ;Get drive # wanted.
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LDA (PTR2IOB),Y
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LDY #16 ;Set (y) = index to last-used drive.
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CMP (PTR2IOB),Y ;Drv wanted vs drv last used.
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BEQ SAMEDRV
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(BD6E) STA (PTR2IOB),Y ;Designate drv wntd as old drv
|
|
;for next time around.
|
|
(BD70) PLP ;Get status back off stk.
|
|
(BD71) LDY #0 ;Reset status (z-flag off) to signal that
|
|
;SPECIFIC DRIVE # we want in SPECIFIC SLOT
|
|
;wanted was not originally spinning.
|
|
(BD73) PHP ;Push updated status back on stk.
|
|
SAMEDRV ROR ;Put low bit of drv wanted in carry.
|
|
BCC USEDRV2 ;Branch if want drive 2.
|
|
LDA SELDRV1,X ;Route power to select drive 1.
|
|
BCS USEDRV1 ;ALWAYS.
|
|
USEDRV2 LDA SELDRV2,X ;Route power to select drive 2.
|
|
USEDRV1 ROR DRVZPG ;Put sign bit for which drive
|
|
(BD7F) ;using in z-page: neg = drive1.
|
|
; pos = drive2.
|
|
|
|
* Chk to see if a specific drive wanted in
|
|
* specific slot wanted was originally on or not.
|
|
(BD81) PLP ;Get previous test result.
|
|
PHP ;Put it back on stk for later use.
|
|
(BD83) BNE WASON ;Orig drv in orig slot was on.
|
|
|
|
* Specific drive wanted in specific slot
|
|
* wanted was ORIGINALLY OFF, so delay a
|
|
* bit to avoid positioning head during
|
|
* the period of heavy current flow that
|
|
* occurs when motor is turned on. (That
|
|
* is, give line/capacitor time to
|
|
* bleed down cause motor on/off switch
|
|
* requires more current than stepper motor.)
|
|
*
|
|
* (Amount of delay is not constant cause
|
|
* it depends on what is in accum & we don't
|
|
* know cause we were just accessing hardware.)
|
|
(BD85) LDY #7
|
|
WAIT4MTR JSR DELAY ;Stall.
|
|
(BD87)
|
|
|
|
* Main delay routine in DOS.
|
|
* (Amt of delay = 100 * (a) microsecs.)
|
|
(BA00)
|
|
DELAY LDX #17
|
|
DLY1 DEX
|
|
BNE DLY1
|
|
INC MTRTIME
|
|
BNE DLY2
|
|
INC MTRTIME+1
|
|
DLY2 SEC
|
|
SBC #1
|
|
BNE DELAY
|
|
(BA10) RTS
|
|
|
|
(BD8A) DEY
|
|
(BD8D) BNE WAIT4MTR ;Go stall some more.
|
|
LDX SLOTPG5 ;Restore (x) = slot*16.
|
|
(BD90)
|
|
WASON LDY #4 ;Get trk wanted.
|
|
LDA (PTR2IOB),Y
|
|
(BD94) JSR SEEKTRK ;Go move arm to desired trk.
|
|
|
|
(BE5A)
|
|
SEEKTRK PHA ;Save # of trk wntd on stk.
|
|
LDY #1 ;Get drive type (1- or 2-phase)
|
|
(BE5D) LDA (PTR2DCT),Y ;from DCT. (P.S. the "II" in the
|
|
;"DISK II" logo stamped on Apple's
|
|
;disk drive denotes a two-phase
|
|
;stepper motor.)
|
|
(BE5F) ROR ;Put low byte of drive type in carry.
|
|
PLA ;Get trk# wanted back in (a).
|
|
(BE61) BCC SEEKIT ;Not using standard DRIVEII, using a
|
|
;one-phase drive instead, ther4 skip
|
|
;doubling of trk # & use SEEKIT as part
|
|
;of routine instead of a subroutine.
|
|
|
|
* Using a two-phase drive.
|
|
(BE63) ASL ;Double trk # wanted to get
|
|
;number of halftrk wanted.
|
|
(BE64) JSR SEEKIT ;Move disk arm to desired track.
|
|
|
|
(BE6B)
|
|
SEEKIT .
|
|
.
|
|
.
|
|
---------------------------------------------
|
|
l * Routine/subroutine to move drive arm
|
|
l * to a specific trk position.
|
|
l * Used as a subroutine when using Apple's
|
|
l * disk drive II. Note when SEEKIT is used as a
|
|
l * subroutine, DESTRK, PRESTRK, TRK4DRV1, TRK4DRV2,
|
|
l * STPSDONE and HOLDPRES are all expressed in half
|
|
l * tracks:
|
|
l * DESTRK = destination half-track position.
|
|
l * PRESTRK = present half-track position.
|
|
l * HOLDPRES = present half-track position.
|
|
l * TRK4DRV1 = base addr (when indexed by slot*16) pts
|
|
l * at the addr that contains the last half-
|
|
l * track # that drive 1 was aligned on.
|
|
l * TRK4DRV2 = base addr (when indexed by slot*16) pts
|
|
l * at the addr that contains the last half-
|
|
l * track # that drive 2 was aligned on.
|
|
l * STPSDONE = number of half tracks moved so far.
|
|
l * If not using a II-phase drive, change all
|
|
l * comments that read "half tracks" to read
|
|
l * "full tracks".
|
|
l (BE6B)
|
|
l SEEKIT STA DESTRK ;(a) = 2*trk # wanted.
|
|
l ; = # of halftrk wanted.
|
|
l (BE6D) JSR SLOTX2Y ;Set (y) = slot.
|
|
l
|
|
l * Convert slot*16 from
|
|
l * (x) to slot in (y).
|
|
l (BE8E)
|
|
l SLOTX2Y TXA ;Get slot*16 from (x).
|
|
l LSR ;Divide it by 16.
|
|
l LSR
|
|
l LSR
|
|
l LSR
|
|
l TAY ;Put slot # in (y).
|
|
l (BE94) RTS
|
|
l
|
|
l (BE70) LDA TRK4DRV1,Y ;Pres halftrk# assoc with drv1.
|
|
l (BE73) BIT DRVZPG ;Contains: neg = drive 1.
|
|
l ; pos = drive 2.
|
|
l (BE75) BMI SETPRSTK ;Branch if using drive 1.
|
|
l LDA TRK4DRV2,Y ;Using drv 2 so get pres 1/2trk#.
|
|
l SETPRSTK STA PRESTRK ;Save present halftrk#.
|
|
l (BE7A)
|
|
l
|
|
l * Designate halftrk we are about to seek
|
|
l * as present halftrk for next time around.
|
|
l * (Put halftrk info in slot dependent locations.)
|
|
l (BE7D) LDA DESTRK
|
|
l BIT DRVZPG ;Chk to see which drive we are using.
|
|
l BMI DRV1USG ;Branch if using drive 1.
|
|
l STA TRK4DRV2,Y ;Using drv2 -store halftrk 4 next time.
|
|
l BPL DRV2USG ;ALWAYS.
|
|
l DRV1USG STA TRK4DRV1,Y ;Using drv1 -store halftrk 4 next time.
|
|
l DRV2USG JMP SEEKABS
|
|
l (BE8B) -----------
|
|
l
|
|
l * Move disk arm to a given halftrk position.
|
|
l * On entry: (x) = slot *16.
|
|
l * (a) = destination halftrack pos'n.
|
|
l * PRESTRK = current halftrack pos'n.
|
|
l
|
|
l (B9A0)
|
|
l SEEKABS STX SLT16ZPG ;Save slot*16 in z-page.
|
|
l STA DESTRK ;Save destin halftrk #.
|
|
l CMP PRESTRK ;Dest halftrk = pres halftrk?
|
|
l BEQ ARRIVED ;Yes - we are already there, so exit.
|
|
l LDA #0 ;Init counter 4 # of halftrks moved.
|
|
l (B9AB) STA STPSDONE
|
|
l
|
|
l * Save current halftrk pos'n & calc
|
|
l * number of halftrks need to move minus 1.
|
|
l (B9AD)
|
|
l SAVCURTK LDA PRESTRK ;Save current halftrk pos'n.
|
|
l STA HOLDPRES
|
|
l SEC ;Calc (PRESTRK - DESTRK).
|
|
l SBC DESTRK
|
|
l BEQ ATDESTN ;At destin halftrk so go shutdown.
|
|
l (B9B7) BCS MOVDWN ;Pres halftrk > destin halftrk so
|
|
l ;want to move to lower trk.
|
|
l
|
|
l * Want to move to a higher halftrk #
|
|
l * (PRESTRK - DESTRK = neg result).
|
|
l
|
|
l (B9B9) EOR #$FF ;Convert neg to pos.
|
|
l (B9BB) INC PRESTRK ;Moving up, so inc current 1/2
|
|
l ;trk pos'n for next time around.
|
|
l (B9BE) BCC CKDLYNDX ;ALWAYS.
|
|
l ------------
|
|
l
|
|
l * Want to move to lower halftrk #
|
|
l * (PRESTRK - DESTRK = pos result).
|
|
l (B9C0)
|
|
l MOVDOWN ADC #$FE ;Simulate a subtract of 1. Actually
|
|
l ;adding minus 1 (#$FF) cause carry
|
|
l ;set. Want (a) to equal 1 less than
|
|
l ;number of halftrks to move.
|
|
l (B9C2) DEC PRESTRK ;Moving down so reduce pres 1/2
|
|
l ;trk number for next time around.
|
|
l
|
|
l * Check to see which index to use to
|
|
l * access the delay table. IF WE ARE
|
|
l * WITHIN 12 STEPS of the destination
|
|
l * or start positions, then use closest
|
|
l * distance to start or end pos'n to
|
|
l * index delay tables. Delay tables are
|
|
l * only 12 bytes long, so if more than 12
|
|
l * steps away from both start & destination,
|
|
l * then use last index (y=12) to access table.
|
|
l
|
|
l * Check if closer to destination or start pos'n.
|
|
l (B9C5)
|
|
l CKDLYNDX CMP STPSDONE ;Compare # of halftrks moved
|
|
l ;to # of halftrks need to move.
|
|
l (B9C7) BCC CLSR2ND ;Branch if closer to destn than start posn.
|
|
l
|
|
l * Closer to start.
|
|
l (B9C9) LDA STPSDONE ;Set (a) = dist from start pos'n.
|
|
l CLSR2ND CMP #12 ;Are we within 12 steps of start
|
|
l ;or destination pos'n?
|
|
l (B9CD) BCS TURNON ;We are at or beyond 12 steps from
|
|
l ;start or destn pos'n so use old
|
|
l ;index to access delay table.
|
|
l (B9CF)
|
|
l PRESNDX TAY ;Use present distance to index delay table.
|
|
l TURNON SEC ;Set carry so get odd index to base addr so
|
|
l (B9D0) ;magnet will be turned ON.
|
|
l (B9D1) JSR ONOROFF ;Turn magnet ON to suck stepper motor
|
|
l ;to correct halftrack pos'n.
|
|
l
|
|
l (B9EE)
|
|
l ONOROFF LDA PRESTRK ;Use lwr 2 bits of
|
|
l ENTRYOFF AND #%00000011 ;1/2 trk pos'n to
|
|
l ;index magnet.
|
|
l (B9F3) ROL ;2*halftrack+(c).
|
|
l ;If carry set,
|
|
l ;result is odd &
|
|
l ;magnet is energized.
|
|
l (B9F4) ORA SLT16ZPG ;Merge index to magnet
|
|
l ;with slot #.
|
|
l (B9F6) TAX ;Use (x) for indexing.
|
|
l (B9F7) LDA MAG0FF,X ;Use magnet0 off as
|
|
l ;base address.
|
|
l (B9FA) LDX SLT16ZPG ;Restore (x)=slot*16.
|
|
l ARRIVED RTS
|
|
l (B9FC)
|
|
l
|
|
l (B9D4) LDA ONTABLE,Y ;Get time 2 leave magnet on from tbl.
|
|
l (B9D7) JSR DELAY ;Delay to give drive time to act before
|
|
l ;magnet is turned off again cause computer
|
|
l ;too fast 4 peripheral & want smooth mov't.
|
|
l
|
|
l * Main delay routine in DOS.
|
|
l * (Amt of delay = 100 * (a) microsecs.)
|
|
l (BA00)
|
|
l DELAY LDY #17
|
|
l DLY1 DEX
|
|
l BNE DLY1
|
|
l INC MTRTIME
|
|
l BNE DLY2
|
|
l INC MTRTIME+1
|
|
l DLY2 SEC
|
|
l SBC #1
|
|
l BNE DELAY
|
|
l (BA10) RTS
|
|
l
|
|
l (B9DA) LDA HOLDPRES ;Get last halftrk pos'n in (a).
|
|
l (B9DE) CLC ;Clr carry so index will come out even
|
|
l ;and there4 magnet will be turned OFF.
|
|
l (B9DD) JSR ENTRYOFF ;Turn magnet assoc with prev pos'n off.
|
|
l
|
|
l (B9F1)
|
|
l ENTRYOFF AND #%00000011 ;Halftrk pos'n to
|
|
l ;index magnet.
|
|
l (B9F3) ROL ;2*halftrk+(c).
|
|
l ;If carry set,
|
|
l ;result is odd &
|
|
l ;magnet is energized.
|
|
l (B9F4) ORA SLT16ZPG ;Merge index to magnet
|
|
l ;with slot #.
|
|
l (B9F6) TAX ;Use (x) for indexing.
|
|
l (B9F7) LDA MAG0FF,X ;Use magnet0 off as
|
|
l ;base address.
|
|
l (B9FA) LDX SLT16ZPG ;Restore (x)=slot*16.
|
|
l ARRIVED RTS
|
|
l (B9FC)
|
|
l
|
|
l (B9E0) LDA OFFTABLE,Y ;Get time 2 leave magnet off from table.
|
|
l (B9E3) JSR DELAY ;Leave magnet off for a while to give
|
|
l ;arm time to be properly aligned.
|
|
l ;(Need time to suck it over & also to
|
|
l ;decrease bounce or over-shoot.)
|
|
l
|
|
l * Main delay routine in DOS.
|
|
l * (Amt of delay = 100 * (a) microsecs.)
|
|
l (BA00)
|
|
l DELAY LDY #17
|
|
l DLY1 DEX
|
|
l BNE DLY1
|
|
l INC MTRTIME
|
|
l BNE DLY2
|
|
l INC MTRTIME+1
|
|
l DLY2 SEC
|
|
l SBC #1
|
|
l BNE DELAY
|
|
l (BA10) RTS
|
|
l
|
|
l (B9E6) INC STPSDONE
|
|
l (B9E8) BNE SAVCURTK ;ALWAYS.
|
|
l ------------
|
|
l
|
|
l * Arrived at destination halftrack.
|
|
l (B9EA)
|
|
l ATDESTN JSR DELAY ;Wait for peripheral again.
|
|
l
|
|
l * Main delay routine in DOS.
|
|
l * (Amt of delay = 100 * (a) microsecs.)
|
|
l (BA00)
|
|
l DELAY LDY #17
|
|
l DLY1 DEX
|
|
l BNE DLY1
|
|
l INC MTRTIME
|
|
l BNE DLY2
|
|
l INC MTRTIME+1
|
|
l DLY2 SEC
|
|
l SBC #1
|
|
l BNE DELAY
|
|
l (BA10) RTS
|
|
l
|
|
l * Turn last-used magnet off so exit with all
|
|
l * phases (ie. magnets) off becaue MAG1ON is
|
|
l * wired into the write-protect switch.
|
|
l (B9ED) CLC ;Turn magnet OFF.
|
|
l
|
|
l * Turn magnet on or off.
|
|
l (B9EE)
|
|
l ONOROFF LDA PRESTRK ;Use halftrk pos'n 2 index magnet.
|
|
l ENTRYOFF AND #%00000011 ;Only keep lwr 2 bits of halftrk#
|
|
l (B9F1) ;cause only 4 magnets (0,1,2, & 3).
|
|
l (B9F3) ROL ;Multiply halftrk# * 2 and add (c)
|
|
l ;If (c)=1, result even, magnet off
|
|
l ;If (c)=0, result odd, magnet on
|
|
l (B9F4) ORA SLT16ZPG ;Merge index to magnet with slot #.
|
|
l TAX ;Use (x) for indexing.
|
|
l LDA MAG0FF,X ;Use magnet-0-off as base addr.
|
|
l LDX SLT16ZPG ;Restore slot*16 in (x).
|
|
l ARRIVED RTS
|
|
l (B9FC)
|
|
l--------------------------------------------
|
|
.
|
|
.
|
|
.
|
|
-----------------------
|
|
l
|
|
l
|
|
(BE67) LSR PRESTRK ;Calc present whole trk #
|
|
;(ie. pres halftrk# / 2).
|
|
(BE6A) RTS
|
|
|
|
* Check to see if motor was originally on.
|
|
(BD97) PLP ;Get prev motor test result off stack.
|
|
BNE BEGINCMD ;Branch if motor was originally on.
|
|
(BD9A) LDY MTRTIME+1 ;Motor not originally on, but have since
|
|
;turned it on. Has it been on long enough?
|
|
(BD9C) BPL BEGINCMD ;Yes - no need to wait any longer.
|
|
|
|
* Although motor was turned on, it hasn't
|
|
* been on long enough to do accurate
|
|
* reading of bytes. There4, delay until
|
|
* motor on time is 1 second (at which time
|
|
* MTRTIME count is zero). (Part of time was
|
|
* taken up to seek track.)
|
|
(BD9E)
|
|
TIME1 LDY #18
|
|
TIME2 DEY
|
|
BNE TIME2
|
|
INC MTRTIME
|
|
BNE TIME1
|
|
INC MTRTIME+1
|
|
(BDA9) BNE TIME1
|
|
|
|
* Motor is up to speed so now process command.
|
|
* (Seek=00, Read=01, Write=02, Format=04.)
|
|
* Counters:
|
|
* READCNTR = allow up to 48 times to find correct
|
|
* addr prologue between re-seeking.
|
|
* RSEEKCNT = allow up to 4 re-seeks btwn recalibrations.
|
|
* RECLBCNT = allow up to 2 recalibrations.
|
|
* (There4, if necessary, allow up to 384
|
|
* attempts to find correct prologue addr.)
|
|
|
|
* Begin RWTS command processing.
|
|
(BDAB)
|
|
BEGINCMD LDY #12 ;Get cmd from IOB.
|
|
LDA (PTR2IOB),Y
|
|
BEQ WASEEK ;Branch if cmd was "seek".
|
|
CMP #4 ;Was cmd "format"?
|
|
(BDB3) BEQ FORMDSK ;Branch if command was "format".
|
|
----------
|
|
|
|
* Command was FORMAT (opcode = $04).
|
|
(BE0D)
|
|
FORMDSK JMP FORMAT
|
|
----------
|
|
|
|
* Do the FORMAT.
|
|
(BEAF)
|
|
FORMAT LDY #3 ;Get vol from IOB & store it in z-page.
|
|
LDA (PTR2IOB),Y
|
|
STA FRMTVOL
|
|
LDA #$AA ;Store "AA" as constant in z-page.
|
|
STA HOLDAA
|
|
LDY #$56 ;Initialize index to buffer.
|
|
LDA #0 ;INITIALIZE THE TRACK COUNTER.
|
|
(BEBD) STA FRMTKCTR ;(IE. ALWAYS START FORMATTING WITH TRK0.)
|
|
|
|
* Zero out the RWTS buffers.
|
|
* Note: When formatting, these "$00"
|
|
* memory bytes will later be written to the
|
|
* disk as "$96" disk bytes.
|
|
|
|
* Zero out the RWTS buffer that normally
|
|
* contains 2-encoded nibbles.
|
|
* (RWTSBUF2, $BC00 <------------- $BC55.)
|
|
(BEBF)
|
|
ZBUF2 STA RWTSBUF1+$FF,Y ;($BC55 --> $BC00)
|
|
DEY
|
|
(BEC3) BNE ZBUF2
|
|
|
|
* Zero out RWTS buffer that normally
|
|
* contains 6-encoded nibbles.
|
|
* (RWTSBF1, $BB00 ------------> $BBFF)
|
|
(BEC5)
|
|
ZBUF1 STA RWTSBUF1,Y
|
|
DEY
|
|
(BEC9) BNE ZBUF1
|
|
|
|
* Prepare to do a recalibration.
|
|
(BECB) LDA #80 ;Pretend we're on trk #80.
|
|
(BECD) JSR SETTRK ;Go select drive & put trk wanted in
|
|
;memory location specific to drive.
|
|
|
|
(BE95)
|
|
SETTRK PHA ;Save present trk on stack.
|
|
LDY #2 ;Get drive # wanted from IOB.
|
|
LDA (PTR2IOB),Y
|
|
(BE9A) ROR ;Condition carry:
|
|
; clr=drv1, set=drv2.
|
|
(BE9B) ROR DRVZPG ;Condition zero-page loc:
|
|
; neg=drv1, pos=drv2.
|
|
(BE9D) JSR SLOTX2Y ;Set (y) = slot.
|
|
|
|
* Convert slot*16 from (x)
|
|
* to slot in (y).
|
|
(BE8E)
|
|
SLOTX2Y TXA ;Get slot*16 from (x).
|
|
LSR ;Divide it by 16.
|
|
LSR
|
|
LSR
|
|
LSR
|
|
TAY ;(y) = slot.
|
|
(BE94) RTS
|
|
|
|
(BEA0) PLA ;Get trk wanted off stk.
|
|
ASL ;Times 2 for half track.
|
|
BIT DRVZPG ;Check which drive to use.
|
|
BMI STORDRV1 ;Branch if using drive 1.
|
|
STA TRK4DRV2,Y ;Save halftrack wanted for drv2.
|
|
BPL RTNSETRK ;ALWAYS.
|
|
STORDRV1 STA TRK4DRV1,Y ;Save halftrack wanted for drv1.
|
|
RTNSETRK RTS
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(BEAE)
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(BED0) LDA #40 ;Set up for 40 syncs between secs
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(BED2) STA SYNCNTR ;on track ZERO. THIS NUMBER WILL LATER
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|
;BE REDUCED AS WE WRITE SUBSEQUENT TRKS.
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;(Higher numbered tracks are closer to
|
|
;the center of the disk and therefore are
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|
;represented by smaller circles. We can
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|
;crowd all the sectors into a smaller
|
|
;circumference by reducing the number of
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|
;sync bytes between sectors.)
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* Format the next track.
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|
(BED4)
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|
FRMNXTRK LDA FRMTKCTR ;Use trk counter as trk to seek.
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(BED6) JSR SEEKTRK ;Move read/write head to correct trk.
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|
(BE54)
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SEEKTRK .
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|
.
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|
(See dis'mbly above.)
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|
.
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|
.
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|
(RTS)
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|
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* Go format a specific track.
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|
(BED9) JSR FORMATRK ;Go format a track.
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|
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* Format a specific track.
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|
* Sectors are written in ascending
|
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* order from sec $00 to sec $0F.
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* (Note that the format routine
|
|
* only deals with PHYSICAL sector
|
|
* numbers.)
|
|
(BF0D)
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|
FORMATRK LDA #0
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|
STA FRMTSEC ;ALWAYS START WITH SECTOR $00.
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|
(BF11) LDY #128 ;USE 128 SYNC BYTES BEFORE SEC $00.
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|
;NOTE THAT PART OF THIS GAP WILL BE
|
|
;PARTIALLY OVERWRITTEN BY SEC $0F.
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(BF13) BNE DOADDR ;ALWAYS.
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|
-----------
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|
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|
(BF15)
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FRMTASEC LDY SYNCNTR ;Set (y) = # of 40-cycle self-sync bytes
|
|
;to be written between sectors. (THIS
|
|
;NUMBER VARIES DEPENDING ON WHICH TRACK
|
|
;IS BEING WRITTEN AND THE SPEED OF THE
|
|
;SPECIFIC DRIVE BEING USED.)
|
|
DOADDR JSR WRITADR ;Write sync bytes and addr header.
|
|
(BF17)
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|
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* Write sync gap & addr header.
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* (On entry: (x) = slot * 16,
|
|
* (y) = # of self-syncs to write,
|
|
* HOLDAA = #$AA, FRMTSEC = sec #,
|
|
* FRMTVOL = vol #, FRMTKCTR = trk #.)
|
|
(BC56)
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|
WRITADR SEC ;(c)=1, default err.
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LDA Q6H,X ;Chk if write prot.
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LDA Q7L,X
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|
(BC5D) BMI SET4RD ;Take if writ prot.
|
|
|
|
* Not write protected, so write a gap of
|
|
* 40-cycle self-sync bytes between
|
|
* sectors. (This routine writes two
|
|
* different sizes of gaps. Gap1 preceeds
|
|
* sector $00. It initially consists of
|
|
* 128 self-sync bytes but is later
|
|
* partially overwritten by sector $0F.
|
|
* Gap 3 occurs between the address field
|
|
* of the preceeding sector and the data
|
|
* field of the next sector. Its length
|
|
* varies with the track # and the speed of
|
|
* the specific drive being used.)
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|
(BC5F) LDA #$FF ;(a) = sync byte.
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|
STA Q7H,X ;Set write mode.
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|
CMP Q6L,X
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|
PHA ;(3 cyc)
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|
PLA ;(4 cyc)
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|
WRTSYNC JSR WTADDRTN ;(12 cyc)
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|
JSR WTADDRTN ;(12 cyc)
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|
STA Q6H,X ;(5 cyc)
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|
CMP Q6L,X ;(4 cyc, write byte)
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|
NOP ;(2 cyc)
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|
DEY ;(2 cyc)
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|
(BC77) BNE WRTSYNC ;(3 or 2 cyc)
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|
|
|
* Write address prologue.
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|
* ("D5 AA 96", 32-cycle bytes)
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|
(BC79) LDA #$D5 ;(2 cyc)
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|
(BC7B) JSR WRBYTE3 ;(24 before, 6 after)
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|
;(See dis'mbly below.)
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|
(BC7E) LDA #$AA ;(2 cyc)
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|
(BC80) JSR WRBYTE3 ;(24 before, 6 after)
|
|
;(See dis'mbly below.)
|
|
(BC83) LDA #$96 ;(2 cyc)
|
|
(BC85) JSR WRBYTE3 ;(24 before, 6 after)
|
|
;(See dis'mbly below.)
|
|
|
|
* Write vol, trk & sector as
|
|
* odd/even encoded bytes.
|
|
* (32 cycles between bytes.)
|
|
(BC88) LDA FRMTVOL ;Vol# (3 cyc)
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|
(BC8A) JSR WRBYTE1 ;Write byte 4 vol
|
|
;("JSR" = 6 cyc)
|
|
|
|
(BCC4)
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|
WRBYTE1 PHA ;(3)
|
|
|
|
* Calc & write
|
|
* odd-encoded byte.
|
|
(BCC5) LSR ;(2)
|
|
ORA HOLDAA ;(3)
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|
STA Q6H,X ;(5)
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|
(BCCB) CMP Q6L,X ;(4)
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|
|
|
* Calc & write
|
|
* even-encoded byte.
|
|
(BCCE) PLA ;(4)
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|
NOP ;(2)
|
|
NOP ;(2)
|
|
NOP ;(2)
|
|
(BCD2) ORA #$AA ;(2)
|
|
|
|
(BCD4)
|
|
WRBYTE2 NOP ;(2)
|
|
|
|
(BCD6)
|
|
WRBYTE3 NOP ;(2)
|
|
PHA ;(3)
|
|
PLA ;(4)
|
|
STA Q6H,X ;(5l
|
|
CMP Q6L,X ;(4)
|
|
(BCDE) RTS ;(6)
|
|
|
|
(BC8D) LDA FRMTKCTR ;Write bytes 4 trk.
|
|
;(3 + 6 from before)
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|
(BC8F) JSR WRBYTE1 ;(6 + 17 more cyc,
|
|
;+ 6 residual cyc)
|
|
;(See dis'mbly above)
|
|
(BC92) LDA FRMTSEC ;Write bytes for sec
|
|
(BC94) JSR WRBYTE1 ;(6 + 17 more cyc,
|
|
;+ 6 residual cyc)
|
|
;(See dis'mbly above)
|
|
|
|
* Calculate address checksum.
|
|
(BC97) LDA FRMTVOL ;(3 cyc + 6 from b4)
|
|
EOR FRMTKCTR ;(3 cyc)
|
|
EOR FRMTSEC ;(3 cyc)
|
|
(BC9D) PHA ;Put cksum on stk
|
|
;(3 cyc)
|
|
|
|
* Odd encode the address checksum.
|
|
(BC9E) LSR ;(2 cyc)
|
|
ORA HOLDAA ;(3 cyc)
|
|
STA Q6H,X ;(5 cyc - write byte)
|
|
(BCA4) LDA Q6L,X ;(4 cyc)
|
|
|
|
* Even encode the address checksum.
|
|
(BCA7) PLA ;(3 cyc)
|
|
ORA #%10101010 ;(2 cyc)
|
|
(BCAA) JSR WRBYTE2 ;(26 b4, 6 after)
|
|
;(See dis'mbly above)
|
|
|
|
* Write address epilogue.
|
|
("DE AA EB", 32-cycle bytes.)
|
|
(BCAD) LDA #$DE ;(2 cyc + 6 from b4.)
|
|
(BCAF) JSR WRBYTE3 ;(24 b4, 6 after)
|
|
;(See dis'mbly above)
|
|
(BCB2) LDA #$AA ;(2 cyc + 6 from b4)
|
|
(BCB4) JSR WRBYTE3 ;(24 b4, 6 after)
|
|
;(See dis'mbly above)
|
|
(BCB7) LDA #$EB ;(2 cyc + 6 from b4)
|
|
(BCB9) JSR WRBYTE3 ;(24 b4, 6 after)
|
|
;(See dis'mbly above)
|
|
(BCBC) CLC
|
|
SET4RD LDA Q7L,X ;Set read mode.
|
|
LDA Q6L,X
|
|
WTADDRTN RTS
|
|
(BCC3)
|
|
|
|
(BF1A) BCS VRFYRTN ;Disk was write protected.
|
|
(BF1C) JSR WRITESEC
|
|
|
|
* Write sector to disk ($B82A-$B8B7).
|
|
* On entry: (x) = slot *16.
|
|
* On exit: if error (c) = 1.
|
|
* if no error (c) = 0,
|
|
* (a) = ?
|
|
* (x) = slot*16
|
|
* (y) = #$00
|
|
(B82A)
|
|
WRITESEC SEC ;(c) = 1, assume
|
|
;write-protect error
|
|
;as default condition.
|
|
(B82B) STX FRMTSLOT ;Save slot*16.
|
|
STX SLOTPG6 ;in pages 0 and 6.
|
|
LDA Q6H,X ;Chk if protected.
|
|
LDA Q7L,X
|
|
BMI PROTECTD ;Branch if prot'd.
|
|
LDA RWTSBUF2 ;Get 1rst 2-encoded
|
|
(B83B) STA HOLDNIBL ;& save it 4 later.
|
|
|
|
* Write a 5-sync gap between address
|
|
* epilogue and data prologue.
|
|
(B83D) LDA #$FF ;(a) = sync byte.
|
|
STA Q7H,X ;Write 1 sync byte.
|
|
ORA Q6L,X
|
|
PHA ;(3 cyc)
|
|
PLA ;(4 cyc)
|
|
NOP ;(2 cyc)
|
|
(B848) LDY #4 ;Write 4 more syncs.
|
|
(B84A) ;(2 cyc)
|
|
WRITE4FF PHA ;(3 cyc)
|
|
PLA ;(4 cyc)
|
|
(B84C) JSR WRITE2 ;(12 before, 6 after.)
|
|
|
|
(B8B9)
|
|
WRITE2 PHA ;(3)
|
|
PLA ;(4)
|
|
WRITE3 STA Q6H,X ;(5)
|
|
ORA Q6L,X ;(4)
|
|
(B8C1) RTS ;(6)
|
|
|
|
(B84F) DEY ;(2 cyc)
|
|
(B850) BNE WRITE4FF ;(2 or 3 cyc)
|
|
|
|
* Write data prologue ("D5 AA AD").
|
|
(B852) LDA #$D5 ;(2 cyc)
|
|
(B854) JSR WRITE1 ;(14 cyc b4, 6 after)
|
|
|
|
(B8B8)
|
|
WRITE1 CLC ;(2)
|
|
WRITE2 PHA ;(3)
|
|
PLA ;(4)
|
|
WRITE3 STA Q6H,X ;(5)
|
|
ORA Q6L,X ;(4)
|
|
(B8C1) RTS ;(6)
|
|
|
|
(B857) LDA #$AA ;(2 cyc)
|
|
(B859) JSR WRITE1 ;(14 before, 6 after)
|
|
;(See dis'mbly above.)
|
|
(B85C) LDA #$AD ;(2 cyc)
|
|
(B85E) JSR WRITE1 ;(14 before, 6 after)
|
|
;(See dis'mbly above.)
|
|
|
|
* Convert & write contents of
|
|
* RWTS buffers to disk.
|
|
* (These buffers are always full of
|
|
* "$00" bytes when formatting. The
|
|
* "$00"s are about to be translated to
|
|
* "$96" disk bytes.)
|
|
|
|
* Convert & write 2-encoded
|
|
* nibbles from RWTSBUF2.
|
|
* (EOR to calc (x) & then use (x)
|
|
* as index to table of disk bytes.)
|
|
*
|
|
* #0 EOR $BC55 = (x)
|
|
* $BC55 EOR $BC54 = (x)
|
|
* $BC54 EOR $BC53 = (X)
|
|
* . .
|
|
* . .
|
|
* . .
|
|
* $BC01 EOR $BC00 = (x)
|
|
|
|
(B861) TYA ;(a) = 0.
|
|
LDY #$56 ;(decimal 86)
|
|
BNE DOEOR ;Always.
|
|
GETNIBL LDA RWTSBUF2,Y
|
|
DOEOR EOR RWTSBUF2-1,Y
|
|
TAX ;Index to disk byte.
|
|
LDA DSKNBTBL,X ;Get disk byte.
|
|
LDX FRMTSLOT ;(x) = slot*16.
|
|
STA Q6H,X ;Write byte.
|
|
LDA Q6L,X
|
|
DEY ;(y) = $56 --> $00.
|
|
(B879) BNE GETNIBL ;(Write #86 bytes.)
|
|
|
|
* Convert & write 6-encoded
|
|
* nibbles from RWTSBUF1.
|
|
*
|
|
* $BC00 EOR $BB00 = (x)
|
|
* $BB00 EOR $BB01 = (x)
|
|
* $BB01 EOR $BB02 = (x)
|
|
* . .
|
|
* . .
|
|
* . .
|
|
* $BBFE EOR $BBFF = (x)
|
|
|
|
(B87B) LDA HOLDNIBL ;Norm=val in $BC00.
|
|
NOP
|
|
SCNDEOR EOR RWTSBUF1,Y
|
|
TAX ;Index to disk byte.
|
|
LDA DSKNBTBL,X ;Get byte to write.
|
|
LDX SLOTPG6 ;(x) = slot*16.
|
|
STA Q6H,X ;Write 87th --> 431th
|
|
LDA Q6L,X ;bytes.
|
|
LDA RWTSBUF1,Y
|
|
INY ;(y) = #$00 --> #$FF.
|
|
(B892) BNE SCNDEOR
|
|
|
|
* Convert & write data checksum.
|
|
* (342nd byte, $BBFF ------> (x).)
|
|
(B894) TAX ;Index to table
|
|
;of disk bytes.
|
|
(B895) LDA DSKNBTBL,X ;Dsk byte 2 write.
|
|
LDX FRMTSLOT ;(x) = slot*16.
|
|
(B89A) JSR WRITE3 ;(5 before, 6 after)
|
|
|
|
(B8BB)
|
|
WRITE3 STA Q6H,X ;(5)
|
|
ORA Q6L,X ;(4)
|
|
(B8C1) RTS ;(6)
|
|
|
|
* Write data epilogue ("DE AA EB").
|
|
(B89D) LDA #$DE ;(2 cyc)
|
|
(B89F) JSR WRITE1 ;(14 cyc b4, 6 after)
|
|
;(See dis'mbly above.)
|
|
(B8A2) LDA #$AA ;(2 cyc)
|
|
(B8A4) JSR WRITE1 ;(14 cyc b4, 6 after)
|
|
;(See dis'mbly above.)
|
|
(B8A7) LDA #$EB ;(2 cyc)
|
|
(B8A9) JSR WRITE1 ;(14 cyc b4, 6 after)
|
|
;(See dis'mbly above.)
|
|
|
|
* Write a sync byte.
|
|
(B8AC) LDA #$FF ;(2 cyc)
|
|
(B8AE) JSR WRITE1 ;(14 cyc b4, 6 after)
|
|
;(See dis'mbly above.)
|
|
(B8B1) LDA Q7L,X ;Set READ mode.
|
|
PROTECTD LDA Q6L,X
|
|
(B8B7) RTS
|
|
===========
|
|
.
|
|
.
|
|
(See RWTSDRV1 using FORMAT cont)
|
|
.
|
|
.
|