percom
From: Michael Current (aa700@cleveland.Freenet.Edu)
Date: 10/30/94-03:23:44 AM Z
From: aa700@cleveland.Freenet.Edu (Michael Current)
Subject: percom
Date: Sun Oct 30 03:23:44 1994
From: dh395@cleveland.Freenet.Edu (Steven J Tucker)
Date: 18 Oct 1994 07:57:54 GMT
If anyone is interested, here is a letter I wrote to a guy on how I
convert my percom drives to higher capacitys.
Steve
--
>The model number is AT88-S1PD. It just has one drive in there.
>I can format it in single density just fine but that's about
>it. There aren't any dip switches but there is a 34 pin connector
>and an edge card connector for a printer I think. Is it possible
>that this is only a single density drive? The drive mech. is
>a Tandon I think from the last time I opened it. I think you
>said something about getting a y-connector to handle 2 drives.
>Wouldn't that put a strain on that little power supply inside?
>Just wonderin'. Well, I stop blabbing now. Thanks for any help
>you can give me.
You have the Single Density version of the Percom drive. But ALL percom drives
support DOUBLE SIDED 80 TRACK OPERATION. You can still hook up and 3.5"
drive but you will only get 360k instead of 720k. All Double Density
models are serial numbered RFDXX-sY where XX is the number of tracks
on the mech ORIGINALLY installs, and Y is the number of SIDES on the mech
originally installed.
My percom w/ 720k mechs is labeled RFD40-S1. It originally contained a
FULL HEIGHT single sided 40 track drive. A real beast to remove.
The Tandon Mech inside MAY be a single sided 40 track mech, which was top
of the line at the time it was made, but the controller will support 80
tracks DS.
The 'EDGE CONNECTOR' sticking out the back is a pass through connector to
hook up more floppies. To convert your drive to 3.5" mech do the following:
1: open the drive and REMOVE THE 5.25 mech and toss it in the trash ;)
2: REMOVE THE EDGE CONNECTOR BOARD and the cable that connects it to the
main controller board, there may also be a single ground wire running
from the card to the controller/power supply. Cut this ground wire and
remove the edge connector board. You can discard the edge connector board,
you will never need it again.
3: Buy some 720k drives. Dont bother with 1.44Meg drives, they will just be
a waste of cash since you will only get 720k. The Percom does not support
the higher transfer rate used in 1.44m mode. (Since it didnt exist when
the controller was made ;)
4: This is the tricky part. You will notice the drive connector on the main
board is the exact same type as on a regular IBM floppy drive board!
If you just want 1 360k drive just go get a regular PC internal floppy
drive cable for $1 and plug one end into the board and I end into the
720k drive. If the cable you get has connectors for 2 floppies on it and
a twist in the wire near the middle, DO NOT USE THE PORTION OF THE CABLE
THAT IS TWISTED, USE ONLY THE 2 CONNECTORS BEFORE THE TWIST.
If you want more than 1 3.5" drive, get a STRAIGHT THROUGH cable that has
no twist and more connectors. The Percom Controller wont work correctly
with PC type cables that contain the twisted wire pair.
You can build your own pass-through cable from parts from Radio shack if
need be, just get regular 34pin connectors and a ribbon cable.
5: Power supply considerations. The 3.5" mech will need an adapter to
draw power from the large 4 pin connector on the Percom power supply, this
is a STANDARD PC POWER ADAPTER and should come with your drive. If it
does not it costs $2 at radio shack.
If you want to power more than 1 drive get a standard PC POWER SUPPLY
Y-splitter. The power drain of 2 3.5" drives in my Percom is roughly
only 2/3 of the draw of the single old FH drive. No need to worry about
toasting the power supply. If you want more then 3 drives hooked upto the
unit (it will support 4-8, depending on the 3.5" drive types) I would
suggest you invest in a cheap PC power supply.
6: Drive selection. Drive number selectionis handeled from the drive unit
exclusivly on SD units, set the jumper on the 3.5" drive to D0 or
'Drive A' or whatever is FIRST.
7: Once you get the drive powered and connected, its time to give it a
test. Turn on the drive, carefull not to let anything metallic
come in contact with the main board.
If all is correct you will hear the drive motor spin for about 2 seconds
and the BUSY light on the front will flicker for 2-3 seconds and then
go dark.
If you oriented one of the cable ends backwards (easy to do w/ a homebrew
cable) the drive light will be lit forever when you turn on the drive
and WILL NOT GO OFF. The motor may also spin forever. This will NOT
harm the drive or controller, just reverse one end of one of the cables
and try again.
Hook the drive to a computer and power on the drive, after the light goes
off turn on the computer. If you hooked up the power supply, drive
cables and drive selector CORRECTLY the drive BUSY light should come
on as the Atari tries to boot from it as normal.
Turn both units off.
8: You now have a perfectly good 360k drive! ;) Just get MyDos loaded, hook
up the drive and use the configure option to set the drive controller
to 2 sides, 80 tracks, SINGLE DENSITY. the seek time should be set to
the fastest possible (0 if I recall).
Its been awhile, but I think the options go: High Capacity: NO
Configurable: YES
Double Sided: Yes
Tracks: 80
Seek: (fastest)
9: Format a disk at this density, it takes quite awhile. Write DOS/DUP and
you now have a bootable 360/720k disk!!!! These drives are real
speed demons in SD too, you will love that!
These drives work fine w/ SpartaDos as well (no ultraspeed).
The only modification to the above directions for DD drives is that the RDF
drives have dip switch settings to control the 'drive offset'. You can adjust
these so that physical drive 1 is atari drive 5, etc. these switches are
not present on any of the SD drives I have owned.
/-
--
-- Video game playing, adventure junkie, choclate craving, woman loving,
Limbaugh hating, Trek watching, all around lazy computer fart.
!! Request my *FOR SALE* LISTING OF CLASSIC VIDEO GAME STUFF !! 2000+ Lines !!
--
Michael Current, Keeper of the 8-Bit Atari FAQ & Vendor/Developer Lists
Cleveland Free-Net Atari SIGOp: aa700 / mailto:mcurrent@carleton.edu
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