+Allan Posted August 9, 2019 Share Posted August 9, 2019 I just added a PDF of the Percom Doubler manual for the AT-88 drive if anybody needs it in the future. https://archive.org/details/doublerfortheat88percomdatacorp Allan 2 3 Quote Link to comment Share on other sites More sharing options...
+Allan Posted August 9, 2019 Share Posted August 9, 2019 Here is another Percom drive manual, the Add-On Atari Drives manual. https://archive.org/details/addonataridrivespercomdatacorporation Allan 2 1 Quote Link to comment Share on other sites More sharing options...
Chilly Willy Posted August 10, 2019 Share Posted August 10, 2019 Finally got around to scanning my schematics for the AT88-S1PD. It could use a good cleaning, but I pieced it together and edited some things that got lost in the scan. Percom AT88-S1PD schematic I'm currently typing up my disassembly of the rom. It's a printout with hand written notes... in pencil... in cursive. Well, it was almost 35 years ago. And looking at the schematic and going over the rom, I have to correct something I said earlier in the thread - the AT88-S1PD has the hardware for high speed serial, but not the rom support. The default the code uses is high speed off, which clocks the serial chip at 16X 19230 baud. It's actually off from what the Atari uses (19040 baud), but close enough I guess. If high speed is turned on (and there's nothing in the rom code to do so), it would clock the serial chip at 1X the Atari peripheral port clock. If I were to hazard a guess, I was working on adding the '?' command to the rom - there's plenty of room in the rom for more commands. I'll probably have the rom listing ready to post next weekend. 6 Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted August 10, 2019 Share Posted August 10, 2019 Very nice Chilly Willy! It sounds like you were one of the original firmware authors then, or just your own hacking? Do you have an actual Percom Drive that a dump could be made of it's ROM/EPROM? Your comments about highspeed capability are interesting, because in the Altirra Hardware Reference manual, phaeron's reverse engineering of a Percom RFD-40S1 found this: Quote Communication over the serial I/O bus is handled by a 6850 ACIA. The transmit and receive clocks are hardwired to 19200 baud (4MHz ÷ 13 as the 16x clock, to be exact), so the RFD-40S1 is one of the few drives that cannot do high-speed operation even with modified firmware. But... your schematics show a 6821 in the AT-88S1PD. Is this the case for the AT-88 with the Double Density upgrade as well? Ultraspeed support on a Percom drive would be pretty cool if the hardware is capable.. The only other PERCOM related ROM that has been dumped (in my current day knowledge) is from an Aastra 1001, which appears to use a Percom derivative ROM, or maybe it is actual (later) Percom code. (see ROM dump & pictures and dissasembled source) Quote Link to comment Share on other sites More sharing options...
Chilly Willy Posted August 10, 2019 Share Posted August 10, 2019 I never worked for Percom, I just got lucky when I bought my first floppy for my Atari 400. I ordered their single-density drive, but they upgraded me to the (then brand spanking new) double-density with built-in printer port for free. The printer port is why they have the 6821 in that unit - they use one port for the drive control, and the other port for the printer. I wrote an app for my Olivetti SparkJet printer for the Atari to print various Atari picture formats, then later made a printer driver for it for my Amiga. But back to the AT88. When my brother got a Happy for his 1050, I wondered if the Percom could do higher speeds. I wrote to Percom asking about the schematics, and they sent me a nice BIG blueprint for the model I had. I pulled the EPROM from the Percom and plugged it into an Atari cart with a socket so I could dump it like a regular Atari cart. I should look around for that. Then I wrote a 6809 disassembler for the Atari to make a file of the disassembled code. I printed it out on my SparkJet and made notes on every routine. Before I could get around to actually upgrading the Percom for high speed, I got an Amiga 500 and moved into Amiga programming. 4 Quote Link to comment Share on other sites More sharing options...
Chilly Willy Posted November 3, 2019 Share Posted November 3, 2019 Haven't had the time for typing, so I scanned my rom listing instead. Here's an arc. http://www.mediafire.com/file/856b1fye8ott7cq/PercomRomListingRawScan.7z/file 1 Quote Link to comment Share on other sites More sharing options...
doctor_x Posted November 5, 2019 Share Posted November 5, 2019 that drive "felt" so ancient handling it.. i dont ever remember a single problem in use though.. same time i dont remember it being much faster.... had a pretty brown spined notebook manual with mine.. i cringe to think of what shipping was when i bought that fucker... same with the amdek dual 3" for the Tandy I had for a fleeting moment. Quote Link to comment Share on other sites More sharing options...
doctor_x Posted November 5, 2019 Share Posted November 5, 2019 just as a side note.. dont ever let the percom go.. definitely becoming a rare beast. Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted November 5, 2019 Share Posted November 5, 2019 On 11/3/2019 at 9:48 AM, Chilly Willy said: Haven't had the time for typing, so I scanned my rom listing instead. Here's an arc. First of all, thanks for the scans! I was going to convert this to PDF and ask you permission to post it on Archive.org (may I?) - But I noticed even though your page scans you provided are lossless PNG, upon close inspection, they exhibit heavy JPEG artifacting. Any chance you still have scans of the pages prior to when they got JPEG'd? Or maybe it's just an internal limitation of your scanner... Quote Link to comment Share on other sites More sharing options...
Chilly Willy Posted November 5, 2019 Share Posted November 5, 2019 (edited) 19 hours ago, doctor_x said: just as a side note.. dont ever let the percom go.. definitely becoming a rare beast. I don't plan on it. I've had that Percom forever! 12 hours ago, Nezgar said: First of all, thanks for the scans! I was going to convert this to PDF and ask you permission to post it on Archive.org (may I?) - But I noticed even though your page scans you provided are lossless PNG, upon close inspection, they exhibit heavy JPEG artifacting. Any chance you still have scans of the pages prior to when they got JPEG'd? Or maybe it's just an internal limitation of your scanner... ?? Not sure what you mean... I double-checked the pngs and they are definitely png, and I don't see any artifacts at all. I scanned raw RGB at 200 dpi, and saved as lossless PNG. Maybe your viewer is doing some bad/fast rescaling to show the image. Make sure you look at them at 1:1 as they are BIG scans (2480x3507 typically). But yes, you can make it into a PDF for Archive.org. I get quite a few old manuals from there. Here's a screenshot of part of one at 1:1. Looks good to me... https://i.imgur.com/dXmAlwQ.png Edited November 5, 2019 by Chilly Willy Add pic Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted November 5, 2019 Share Posted November 5, 2019 1 hour ago, Chilly Willy said: I double-checked the pngs and they are definitely png, and I don't see any artifacts at all. If you look even closer than 1:1, there are jpeg-like artifacts in the PNG's in your ZIP, like this: The PDFing process jpeg's them anyway, it's just nice to avoid 2nd generation jpeg if possible... Quote Link to comment Share on other sites More sharing options...
Chilly Willy Posted November 5, 2019 Share Posted November 5, 2019 Oh, um, that's a 200 DPI approximation of 35 years of dust and yellowing printer paper, not artifacts. ? I could scan it at an even higher resolution so you can see the dirt and age in better detail if you want... 1 Quote Link to comment Share on other sites More sharing options...
Chilly Willy Posted November 6, 2019 Share Posted November 6, 2019 Found the bare listing of the rom code. No comments on it, and no labels... just code and data in a plain text file. PERCOM.LST 1 Quote Link to comment Share on other sites More sharing options...
tep392 Posted June 7, 2023 Share Posted June 7, 2023 I just picked up a Percom AT88-S1PD and a Tandon TM50-2 (DSDD) off Ebay. They likely need some repair, but that is half the fun for me. I plan to add the TM50-2 to the AT88-S1PD to make it a dual drive. I might eventually replace the original SSDD Tandon with another TM50-2 so I can have a whopping 720k of storage! 1 Quote Link to comment Share on other sites More sharing options...
moonlight_mile Posted June 8, 2023 Share Posted June 8, 2023 It always strikes me funny that percom pretty much used whatever was on the shelf to build their drives. That is the case for the -s2 double drive unit. You could put 4 1/2 height drives in there. Unfortunately only single sided. Does it have the double density board? Quote Link to comment Share on other sites More sharing options...
tep392 Posted June 8, 2023 Share Posted June 8, 2023 2 hours ago, moonlight_mile said: It always strikes me funny that percom pretty much used whatever was on the shelf to build their drives. That is the case for the -s2 double drive unit. You could put 4 1/2 height drives in there. Unfortunately only single sided. Does it have the double density board? It is funny to put a 1/2 height drive in such a huge case. They won't arrive until tomorrow, but I'm very curious what the board looks like. The later drives had the DD controller on the main board. Quote Link to comment Share on other sites More sharing options...
tep392 Posted June 9, 2023 Share Posted June 9, 2023 On 6/8/2023 at 7:50 AM, moonlight_mile said: Does it have the double density board? The Percom arrived! I haven't tested it yet but did open up for a quick inspection. It does have the FD1795 controller, so should be able to do double density as long as the firmware supports it. The ROM is version 1.11. I don't know anything yet about the various ROM variations. I'm very happy to discover that it has unpopulated component locations for the regulators and caps needed to power a second drive. The installed drive is an MPI 501C. I think this is the same mech used in the Rana 1000. The control board doesn't seem to have any way to set drive number so I'm assuming that is done with the jumpers on the drive itself. I haven't had any luck finding a user manual for this version of the AT88-S1PD. Quote Link to comment Share on other sites More sharing options...
moonlight_mile Posted June 9, 2023 Share Posted June 9, 2023 Yes the drive setting are all on the drive jumpers. You can do drives 1-4. I could be wrong but I think the latest rom is 1.12 for the at’s. But don’t hold me to that. Check out the huge percom thread. Quote Link to comment Share on other sites More sharing options...
moonlight_mile Posted June 9, 2023 Share Posted June 9, 2023 Definitely upload pics of your perc. Quote Link to comment Share on other sites More sharing options...
tep392 Posted June 10, 2023 Share Posted June 10, 2023 I partially disassembled it, so here are some pics of the pieces. The MPI drive is single sided. I found a small piece of metal inside the drive that broke off the open/close lever. I placed it next the part it broke off of for the picture. Here are some shots of the control board and transformer. You can see on the left side of the board where the components are placed for the optional second internal drive power supply. Quote Link to comment Share on other sites More sharing options...
tep392 Posted June 10, 2023 Share Posted June 10, 2023 I tried it out after verifying the voltages were all good. The drive will spin for a couple seconds after I power it up, as expected. But when I try to access the drive, nothing happens and I get a 138 - Device Timeout. It seems that the control board isn't communicating with my Atari. Quote Link to comment Share on other sites More sharing options...
_The Doctor__ Posted June 10, 2023 Share Posted June 10, 2023 It the drive aware of a disk being inserted or the latch being closed? Quote Link to comment Share on other sites More sharing options...
tep392 Posted June 10, 2023 Share Posted June 10, 2023 19 minutes ago, _The Doctor__ said: It the drive aware of a disk being inserted or the latch being closed? Yes. It spins the disk for a little bit when I close the lever. I'm thinking I might test the drive on my old PC. It's a 90's era machine with a 3.5" floppy drive. Maybe I can use it if I get the correct cable. EDIT: Quote Link to comment Share on other sites More sharing options...
JR> Posted June 10, 2023 Share Posted June 10, 2023 3 hours ago, tep392 said: I tried it out after verifying the voltages were all good. The drive will spin for a couple seconds after I power it up, as expected. But when I try to access the drive, nothing happens and I get a 138 - Device Timeout. It seems that the control board isn't communicating with my Atari. Are you sure it's set as d1:? Have you tried booting from a different drive and see if it responds as a different drive number? Quote Link to comment Share on other sites More sharing options...
tep392 Posted June 10, 2023 Share Posted June 10, 2023 7 hours ago, JR> said: Are you sure it's set as d1:? Have you tried booting from a different drive and see if it responds as a different drive number? I’m using SDX and checking for a response to every possible drive number. I ordered a PC cable so I can test the drive on my pc. If it works then I will know the problem is in the Percom control board. Quote Link to comment Share on other sites More sharing options...
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