Percom AT88-S1PD

[+SoulBuster]

Searching for a manual and could not find one online. does anyone have one they can scan for me?

 

Edited April 8, 2014 by SoulBuster

[Paul Westphal]

If you cant find one let me know. I sold one to a buddy last year.

[+SoulBuster]

Does not look like anyone has one, Could you check with your buddy?

[Paul Westphal]

I will have him copy it if you [email protected]

[Paul Westphal]

I will have him copy it if you [email protected]

[AtariGeezer]

I will have him copy it if you [email protected]

Paul, just ask him to copy it and you can post it here

[Chilly Willy]

That looks just like mine.

 

Don't know if I still have the manual, but it really doesn't need one now, does it? The card edge on the back is for a 50-pin Centronics cable for the printer. The pin header on the back is for an optional slave floppy drive (the Percom can handle two floppy drives, and I had a 3.5" floppy connected to it so I could transfer data to/from a PC easier).

 

Certain DOSes support double-density on the Percom... I always used TopDOS. When the Percom is doing double-density, ALL the sectors are 256 bytes instead of 128, but the first three sectors only return 128 bytes of data for backwards compatibility with the single-density boot. You have to write your own floppy code to read/write Atari disks on a PC since PCs default to 512 byte sectors (most controllers handle 128 to 1024 bytes per sector), with half the sectors per track (9 instead of 18). Also, the Atari (and hence all compatibles) used an inverting buffer on the data lines to the floppy controller, so all data on Atari floppies are inverted when read on a PC.

[tschak909]

I always wondered about that, why was an inverting buffer used on the data lines?

 

-Thom

[BillC]

I always wondered about that, why was an inverting buffer used on the data lines?

 

-Thom

From what I understand this is due to a bug on the 810 drive, and to maintain compatibility all drives since have done the same.

[MrMartian]

From what I understand this is due to a bug on the 810 drive, and to maintain compatibility all drives since have done the same.

 

Not truly a bug, but a design decision. The FDC used in the 810 had an inverted data bus, and they just did everything inverted instead of the cost of an octal inverter... <shrug> We now live with that decision..

[+bob1200xl]

The 815 drive has inverted data, compared to the 810.

 

Bob

[Chilly Willy]

Old 8-bit systems used buffer drivers on EVERYTHING because the CPUs were notorious about not sinking enough current for more than a couple chips. The question wasn't why they used a buffer, but why they used an INVERTING buffer. One guess - I have a data book on a few old PC floppy controllers where the typical usage schematic included showed an inverting buffer used. These chips required the data to be inverted. Maybe when they designed the 810, it originally used one of those, but switched to the last second to a new model that DIDN'T use the inverted bus, but by then the boards were already made with the inverter in place.

 

More info... the Percom uses a 6809 processor - I disassembled the BIOS in the Percom along with getting the schematics shortly after getting the thing... I was interested in whether a hack could have been made for faster transfers on the Percom like the Happy was for the Atari floppy. I switched to my new Amiga 500 before anything came of that.

[MrMartian]

More info... the Percom uses a 6809 processor - I disassembled the BIOS in the Percom along with getting the schematics shortly after getting the thing... I was interested in whether a hack could have been made for faster transfers on the Percom like the Happy was for the Atari floppy. I switched to my new Amiga 500 before anything came of that.

 

I've looked into the design, and the Percom uses an actual UART with a fixed clock... No easy way that I could see to make it do ultraspeed.

 

Fixing the DD, that I could probably do.

[+SoulBuster]

Don't know if I still have the manual, but it really doesn't need one now, does it?

It is not that I need one, but more that I want the instructions to every piece of equipment I own. It does not have to be the original, but just that I have it available.

Edited April 14, 2014 by SoulBuster

[Chilly Willy]

I've looked into the design, and the Percom uses an actual UART with a fixed clock... No easy way that I could see to make it do ultraspeed.

 

Fixing the DD, that I could probably do.

They DID support the "?" speed command, but didn't add the hardware needed to divide the UART clock. My thoughts were to add that hardware, but like I said, got interested in the Amiga and lost interest in the A8.

 

The most I wound up doing with the Percom was to add a 720K slave 3.5" drive to it. Well, that and my own printer driver to output images to an Olivetti Sparkjet printer.

[sup8pdct]

 

. When the Percom is doing double-density, ALL the sectors are 256 bytes instead of 128, but the first three sectors only return 128 bytes of data for backwards compatibility with the single-density boot.

 

You will find that with all DD drives. Drive firmware will return 128 bytes for sectors 1-3 tho formatted to 256 bytes.

 

James

[Chilly Willy]

You will find that with all DD drives. Drive firmware will return 128 bytes for sectors 1-3 tho formatted to 256 bytes.

Yeah, it's the easiest way to handle the boot process while keeping the disk in a single format. Well, I suppose the Atari ED method where ALL sectors are 128 is the absolute simplest method, but then the sector numbers can become too big. Switching to a bigger sector keeps the number smaller, but then you have that issue with sectors 1 to 3. It's just too bad they didn't go with a 512 byte sector, which would have made PC transfers a little easier. At least we didn't have to deal with that GCR crap that CBM and Apple computers had.

[Paul Westphal]

I'm still waiting for my buddy to copy it, brother. Hang in there. I will push the issue today.

[Paul Westphal]

I'm still waiting for my buddy to copy it, brother. Hang in there. I will push the issue today.

[+SoulBuster]

I'm still waiting for my buddy to copy it, brother. Hang in there. I will push the issue today.

Thanks for your persistence.

[Theoryman]

I could use a copy of this scan myself, please.

 

I am also looking for schematics for the Percom and for its Double Density daughter card.

 

I have a working single denesity unit but the Double Density daughter card is damaged.

 

--

[Theoryman]

One of these with an 800xl and a few carts went for $208 + shipping on ebay...

 

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=141272451030&ssPageName=ADME:X:RTQ:US:1123

 

I hate those people who bid in at the last second...

 

--

[AtariGeezer]

Searching for a manual and could not find one online. does anyone have one they can scan for me?

 

IMG_20140407_184247_358.jpgIMG_20140407_184307_956.jpg

I went through my storage loft tonight (only took 7 hours ) and found my manual for the AT-88 drives.

I'll scan it over the next few days and will post it here when finished...

[+Larry]

I went through my storage loft tonight (only took 7 hours ) and found my manual for the AT-88 drives.

I'll scan it over the next few days and will post it here when finished...

 

But just think what else you (likely) ran across that you hadn't seen in years!

 

-Larry

[AtariGeezer]

 

But just think what else you (likely) ran across that you hadn't seen in years!

 

-Larry

Well, a year anywho I built the storage loft last April..

But I did find some SF314's and a cable that connects them to the ATR8000 so I can see if those still work on it.