VOGONS


First post, by jbenam

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Hi everyone,

I recently got this weird Xebec ISA card:

IMG_20200214_094619.jpg
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IMG_20200214_094619.jpg
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Xebec Unknown ISA
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I'm not sure what to make of it - the codes on the card lead nowhere on teh internets.

It has a 50 pin header and a 25 pin external connector, so my guess was some kind of SCSI card but I can't see any of the known single card SCSI controllers. Then I thought of SASI controllers, and this might be one... I've dumped the ROM and it contains various stuff like a low level format utility and a string with Xebec Host Adaptor Board 1984/85 (or something like that) so it must be a disk controller of some kind, and bootable at that.

I've stuck it in my 8088 (with Enhanced XT Bios 3.1), and I don't get anything at boot. In my 286 it stops the normal booting and it throws me in a CGA mode screen that complains about a missing BASIC ROM.

I've read online that most SASI controllers should be compatible with early SCSI-1 drives and I've got a IBM WDS-3160 (160MB) which should fit the bill.

Anyone knows how to get this thing to work?

Cheers!

Reply 1 of 13, by derSammler

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I would have guessed SCSI-1 as well, but for that, the card is too dumb. SCSI requires some sort of CPU or micro-controller, but there are only 74LS chips and PALs on the card.

http://retro-net.de/blog.html

Reply 2 of 13, by jbenam

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derSammler wrote on 2020-02-14, 10:32:

I would have guessed SCSI-1 as well, but for that, the card is too dumb. SCSI requires some sort of CPU or micro-controller, but there are only 74LS chips and PALs on the card.

It seems there's only one other picture of an ISA SASI controller on the entire interwebs and it has kinda the same amount of 74LS and PALs. The rest of the cards are for S100 systems and another kind of connector I don't recognise.

Maybe it is a slow as molasses interface that uses the system's CPU for everything?

I'll post the ROM later since it definitely has stuff for hard drives in it. I'm just not sure what kind (must be SASI, at this point). Maybe someone will find it interesting.

Reply 3 of 13, by Horun

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All older ISA SCSI and SASI have terminator resisters on the card near the connectors which your card does not. I am guessing it is an interface card similar to what Apple II and early PC used for some tape drive. The FCC ID came up with next to nothing other than being similar to some Xebec Apple II cards.

First computer was an IBM 3270 workstation with CGA monitor. 🤣

Reply 4 of 13, by jmarsh

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jbenam wrote on 2020-02-14, 10:19:

I've stuck it in my 8088 (with Enhanced XT Bios 3.1), and I don't get anything at boot. In my 286 it stops the normal booting and it throws me in a CGA mode screen that complains about a missing BASIC ROM.

That's just the conclusion of the regular bios boot routine when no disk is found to boot from. The original IBM machines would boot into Basic but most clone makers didn't bother to include it.

Reply 5 of 13, by jbenam

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Horun wrote on 2020-02-15, 01:43:

All older ISA SCSI and SASI have terminator resisters on the card near the connectors which your card does not. I am guessing it is an interface card similar to what Apple II and early PC used for some tape drive. The FCC ID came up with next to nothing other than being similar to some Xebec Apple II cards.

While most do, some don't (notably the Seagate ST-02). It definitely is an hard drive controller as evidenced by the text in the ROM, which I'm attaching to this post.

jmarsh wrote on 2020-02-15, 02:44:

That's just the conclusion of the regular bios boot routine when no disk is found to boot from. The original IBM machines would boot into Basic but most clone makers didn't bother to include it.

I only get that message when the card is inserted. I've tested it on two (or maybe three?) 286 motherboards and they all boot normally asking for a floppy if the card isn't inserted. It also switches to CGA, which is kinda weird.

My hunch is that the ROM needs IBM BASIC for something (displaying the menu?) which is obviously absent on 286 and that is hardcoded for CGA.

Forgot to say that both of my 8088 clones include the basic ROMs, but nothing happens on those systems. Maybe there's a key combination involved?

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    xebec.zip
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    Unknown Xebec ISA ROM
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    CC-BY-4.0

Reply 6 of 13, by Robin4

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I find the following text in the rom:

**200215F**.. Version 2.03 of september 21, 1987 Copyright 1984, 87 Xebec Corporation All right reserved

Cannot boot system from this disk.... Reset or power down the computer and retry.

There is no drive to park. Head have been successfully parked. Operator my power down safely the drive ... Error during parking heads.. Be carefull if you plan to move the drive.

Internal routines for XEBEX host adapter V 2.00 [copyright bla bla as above] <R> Return to operating system. <C> Change current drive number <I> Initialize the drive <T> Diagnostics <P> Parking heads before move disk Enter choice or hit <ESC>

It also have a routine inside to format a harddisk..

~ At least it can do black and white~

Reply 7 of 13, by Horun

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Looked thru the bios and it does appear to be for HD's. I still say it is an interface card and not a full HD controller. There is no way in 1988 that it could do scsi, sasi or winchester directly connected, just not enough electronics. I think it was a mate to an external HD box for XT's that had most of the controller circuitry in the box.

First computer was an IBM 3270 workstation with CGA monitor. 🤣

Reply 8 of 13, by derSammler

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jbenam wrote on 2020-02-15, 21:47:

I only get that message when the card is inserted. I've tested it on two (or maybe three?) 286 motherboards and they all boot normally asking for a floppy if the card isn't inserted. It also switches to CGA, which is kinda weird.

My hunch is that the ROM needs IBM BASIC for something (displaying the menu?) which is obviously absent on 286 and that is hardcoded for CGA.

Sounds to me as if the ROM on the card is using a memory location that is already occupied by other ROMs in an AT. Most likely it overwrites the BIOS part at 0xC800.

http://retro-net.de/blog.html

Reply 9 of 13, by jbenam

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Okay - mystery "solved".

There were some "intelligent" SASI drives which included everything on board, allowing the host adapter to be an extremely stupid and simple board. I suppose this made things simpler for manufacturers since they had just to build different dumb (and cheap) HBAs for different systems while the HD did everything. Considering there are similar versions of this controller for Atari and S100 based systems, it made sense.

According to the following sources:
http://www.atarimania.com/faq-atari-400-800-x … rd-disk_36.html

And most importantly:
https://amaus.net/static/S100/software/rlee/S … I/SASI/SASI.DOC

There were indeed some "intelligent" SASI drives, which these days are obscenely rare and/or expensive.

Since I do not believe I'll easily (or more correctly, cheaply) come into possession of one such drives, my search for cheap SCSI ISA controllers is back on 😁

Thanks everyone for the attention!

Reply 10 of 13, by douglar

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Very informative thread. Reading Vogons, I’m often reminded about things that I forgot, but remember much once I see them. But SASI? I read up on it and it didn’t trigger any forgotten memories. I do remember puzzling over some sparse looking SCSi looking boards once upon a time and someone told me they were for proprietary CD-Rom drives, but your board seems too old too be something like that.

Reply 11 of 13, by Zup

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I don't remember where, but I've seen a photo of an old (maybe MFM) HDD with a board attached to it. The board was actually the HDD controller, connected to the HDD with two floppy-like wires.

It allowed to have a simpler controller on the computer (much like IDE and SATA), and connecting different disks with different interfaces to the same controller on PC... but I doubt that having that board attached to the disk allowed cheaper upgrades 😉

I have traveled across the universe and through the years to find Her.
Sometimes going all the way is just a start...

I'm selling some stuff!

Reply 13 of 13, by eisapc

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I own some Disc Coprocessor Boards (DCB) made by Novell and others. These are as well simple SCSI or SASI Controllers used to attach drives to Netware servers.
Boards do not even have a BIOS nor any kind of CPU, only logic chips.
Other gues could be QIC-02 or QIC-36 Interface used for tape drives.