161 lines
8.2 KiB
Plaintext
161 lines
8.2 KiB
Plaintext
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Generic
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3.5 Inch Double Sided Disk Drive
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for
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The 520/1040 Series
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by
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James Lacassagne
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Purpose: This document is a description of the hook-ups and mod-
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ifications that I found necessary in adding a 3.5 inch
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double sided drive to my Atari(tm) 520. It is intended
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solely as a guide to anyone who is interested in saving
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a few dollars by using an "industry standard" drive in
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place of the Atari SF314.
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Warning: This installation seems to function properly for my sys-
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tem, but I cannot guarantee anything. Also, the only way
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that a saving will result is if a suitable power supply
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is already available, or can be obtained at a very low
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price.
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Requirements: 1 3.5" Double Sided Drive w/ Installation kit @ $130
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(The Unit I used was a Toshiba(tm) ND-352
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which came with a multi-purpose mounting
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kit. BE SURE that the unit is XT compat-
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ible!!(720 K etc))
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1 5v/12vdc Regulated Power Supply @ $ 25
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(The supply must be capable of supplying
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5V.+/-5% @200 mA and 12V.+/-5% @300 mA.
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I saved some money here by using the same
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supply that I used for adding a 5 1/4 in.
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drive as described in numerous articles
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in magazines and on Bulletin Boards.)
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1 34 pin Card Edge Connector @ $ 3
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(Yes, This is the "industry standard"
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used on all XT's and Clones. I got mine
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at Radio Shack (P/N____________).)
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1 Standard Atari(tm) 3.5 in Disk Drive Cable @ $ 8
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(Preferably, one of the After Market types
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6' or so in length.)
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1 Disk Drive Case @ $ ?
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(This is optional--I still haven't found
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a good cheap one, but the drive seems to
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work fine.)
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Procedure: There are two ways to proceed with this project depending
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on whether you want the new drive to be A or B. The Drive
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B method is the simpler, so I will start with it.
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Cut the Standard Drive Cable in half (Save the other
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half for another project--maybe!)
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Strip back about 2" of the outer insulation from the
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cable. Do Not cut off the shield wire (a layer of wire
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woven around the multiple conductors in the cable).
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Carefully unweave the shield, and twist it to form a
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wire of its own.
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Since the 34 pin connector that I used was designed for
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ribbon cable, some ingenuity is required here. Each pin
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on the connector ends in a V shaped stud designed to
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separate the ribbon cable wire and cut only its insul-
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ation when the cover is forced in place. Since most of
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the wires in the cable go to the top row of the con-
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nector (the even numbered pins) and the shield goes
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to the bottom row, along with the wires from pins 3 and
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7 of the Atari connector, I divided them accordingly and
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routed them above and below the connector cover. Very
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carefully, I pushed each wire far enough into the cor-
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responding Vstud to hold it in place. I then forced
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the cover down, forcing the wires the rest of the way
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into the V. By trial and error I found that the two
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ground wires (pins 3 and 7) in the cable did not provide
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a sufficient ground path, causing unreliable drive oper-
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ation. I overcame this by (gasp!) tying the shield to
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ALL of the odd numbered pins on the connector. (That's
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what the twisted shield wire is used for.) Carefully
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lay it over the bottom row of Vstuds before putting
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the connector cover on. The Connections Follow:
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(NOTE: the colors mentioned are for an Atari Cable
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You should check if you are using an After Market
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Cable.)
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34 pin conn. Atari conn. Signal Color
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2 * media chng
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4 N/A in use
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6 N/A d4 sel
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8 4 index yellow
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10 5 d0 sel green
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12 6 d1 sel violet
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14 N/A d2 sel
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16 8 motor on brown
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18 9 direction orange
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20 10 step grey
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22 11 wrt data pink
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24 12 wrt gate lt. blue
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26 13 track 0 lt. brown
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28 14 wrt prot lt. green
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30 1 read data red
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32 2 side 0 white
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34 * rdy/med ch
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(any 3 logic gnd blue
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odd) 7 logic gnd black
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Assemble the Disk Drive and Adapter kit. It should have
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come with a power cable adapter with a std XT con-
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nector on the end. You can either buy a mating
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connector or cut it off and splice directly to the wires.
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(Generally, pin 1 (red) is 5V, pin 4 (yel) is 12V, and
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pins 2&3 (blk) are Ground.) The Installation Kit may
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refer to a jumper on pin 34, but this can be ignored.
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Now, the only modification to the drive can be made.
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On the Installation Kit PC Board, a Jumper must be
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soldered between pin 2 and pin 28 of the Drive Con-
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nector.(This is the one that actually connects to
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the Disk Drive. It is identical in pin layout to the
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Std connector, with pin 2 on the top left as you look
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at it.) This connects the Media Change signal on pin
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2 to the Write Protect signal.(Thanks to Analog2 for
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pointing me in the right direction on this one.)
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These are both open collector, active low signals, and
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can be safely wired together.(wired or configuration)
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This should be all that has to be done to make the
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drive work. Simply plug the cable into the OUT con-
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nector of the first drive or the 1040, and away you
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go.
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If you have a 520 and want this to be drive A, the
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procedure is the same, except DO NOT CUT THE CABLE
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IN HALF. Instead, strip a 3-4 in. section in the
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center of the cable, Cut and unweave 1/2 of the
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shield. Lead the wires over the Vstuds as before,
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but cut the wires from the Atari connector pins 5&
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6.(computer end) Pin 5 wire is connected to the Std
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connector pin 10 and pin 6 wire is connected to the
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remaining end of pin 5.(The part that will go to the
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second drive.) This brings the ds1 signal to the
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ds0 pin on the second drive, just like Atari does it.
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You can cut off the remaining pin 6 wire if you like,
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since it doesn't get used. Don't forget to attach the
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shield to the odd number connector pins.
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If you have understood and followed my directions, the
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drive should function properly. If not, there is not
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much that can cause damage. My version will read and
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format and write to double and single sided disks
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without any problems. If you encounter any difficulty,
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I can be contacted through Delphi as JIMSL or Com-
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puserve No. 72257,1613.
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Atari, Radio Shack, and Toshiba are Registered Trademarks.
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