76 lines
3.6 KiB
Plaintext
76 lines
3.6 KiB
Plaintext
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MiniSport Laptop Hacker - Vol 7 20 Feb 93
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Thanks to W4NTG, N7SXD, KD7HP, and others who have given me feedback the
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last few weeks. I've been hot and heavy into getting TPK1.80 (automated
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mail drop on my local computer) up and running.
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>>> ADMINISTRATIVE
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My packet address remains the same, but notice that my Internet address has
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changed (it's now jupiter rather than visual). Does anybody have a recent
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callbook? Is my address correct in the 1993 Callbook? 6006-B Eaker, Fair-
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child, WA 99011 is the correct address. Send me packets, e-mail, or US
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Mail. I need ideas, questions, and answers!
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The local sysops have frowned on sending back issues through the packet
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network. If you need some back issues, please send me a disk, postage &
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mailer to get it to you. In addition, I've got word back that a 7k
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packet message is too much. I will try to keep them to one page (but
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there's so much good stuff!). What format would you like them in? 80 col-
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umns is ok? 75 columns? Do you print at 6 lpi or 8 lpi?
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>>> COMMUNICATION
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I just came across an easy circuit that lets you wire up bidirectional
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transfers with a parallel port. I need to look at that one a little bit &
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talk about it in an upcoming issue. Has anybody else seen this done?
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But for now, let me pass on some serial port information. Buried inside
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your ML is a more advanced chip that appears like an 8250 programmable
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UART. Eight consecutive addresses are taken by the chip for each communi-
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cation channel. For those of you who are unfamiliar with this concept, let
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me repeat: Each "port" on your IBM/PC compatible really takes up eight
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consecutive addresses. All addresses are used by comm software. On the ML
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there are two blocks of eight addresses: COM1 and COM2. Following is a
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chart introducing the organization of these powerful I/O chips. For exam-
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ple, if you want to check on the CTS, DSR, and RI of COM1, you could read
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in the Modem Status Register at address 0x03FE (hexadecimal). Bits 4,5 and
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6 would give you the condition of the desired lines.
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DLAB A2 A1 A0 8-bit Register Name
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--------------------------------------------------------------
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0 0 0 0 Rcvr buffer (RBR), or Txmtr buffer (THR)
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0 0 0 1 Interrupt Enable (IER)
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x 0 1 0 Interrupt Identification (read only) (IIR)
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x 0 1 1 Line Control (LCR)
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x 1 0 0 Modem Control (MCR)
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x 1 0 1 Line Status (LSR)
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x 1 1 0 Modem Status (MSR)
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x 1 1 1 --- nothing ---
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1 0 0 0 Baud Rate Divisor latch LSB (DLLS)
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1 0 0 1 Baud Rate Divisor latch MSB (DLMS)
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--------------------------------------------------------------
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Note: A2-A0 are the three LSB of a IBM/PC "COM" port address,
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e.g., the MCR (offset of 4) for COM2 (02f8) is available on
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a IBM/PC platform at address 02fc). DLAB is the MSB of the LCR.
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On any PC compatible, the following addresses are in effect:
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Register COM1 COM2
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-------------------------
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RBR & THR | 03F8 02F8
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IER | 03F9 02F9
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IIR | 03FA 02FA
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LCR | 03FB 02FB
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MCR | 03FC 02FC
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LSR | 03FD 02FD
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MSR | 03FE 02FE
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- |
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DLLS | 03F8 02F8
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DLMS | 03F9 02F9
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End of my page. Continued next time...
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>>> UPCOMING
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MORE 8250 DOCS, SERIAL & PARALLEL BUFFER CHIP PINOUTS, COM2 PINOUT, Poor
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Man's Packet INSIDE YOUR MINISPORT, SHRINKING YOUR FAVORITE SOFTWARE, MINI-
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MUM BOOT FILES, BOARD REVISIONS, and more DISASSEMBLY.
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73, Brian, ka9snf@wb7nnf.#spokn.wa or Internet ka9snf@jupiter.spk.wa
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