An unknown SCSI card, can I get it to work?
While rummaging through a box of old 8-bit and 16-bit ISA hardware that I had kept in the garage for some 30 years, I found two PC XT mainboards, each with a NEC V20 processor.
This V20 processor is slightly faster than an 8088, but can also be switched to 8080 mode and for instance run C/PM. That triggered my interest to have a look at these boards again.
But to start off, these boards are IBM XT clone boards, meant to run MS-Dos. So I figured that it was a good idea to start with some low hanging fruit and get them to function as a PC.
Well, that took me down a rabbit hole...
Gathering stuff
First, we need something to connect a monitor to... In the box, there were a bunch of HGC cards and an 8-bit EGA card.
Next, we need something to boot from... And in the box, there were a bunch of floppy controllers, including cables.
We need an XT keyboard... I have held onto a beautiful old 'Mind' keyboard with noisy clicky Cherry switches, which has a switch to switch between PS/2 and XT keyboard mode.
Power supply... Found one with XT power connectors.
A floppy drive is necessary... In another box, I had a bunch of 5.25" drives, but also some 3.5" drives. They are 1.44MB drives, while the controllers all have a NEC upd765 controller. As far as I know, that means Double Density, so max 720KB out of a 3.5" floppy drive.
And mass storage... Ah, hmm... It appeared my box only contained a few 16-bit ISA MFM and RLL controllers, and those won't work on a simple XT mainboard. Having a few MFM hard disks in yet another box didn't change that fact. So, too bad, but we can't use them.
Rummaging... More rummaging... And there it was: an 8-bit SCSI controller!
Looked quite simple, a BIOS, a few dip switches, and a connector, what can go wrong? I decided to try it.
Lastly I dug up a Seagate ST12400N drive from yet another box, and thought I was all set.
Setting it all up
I had two mainboards, both with a NEC V20 in them. One 'Fujitech XT Turbo Board', and one '10MHz Turbo Board', basically a noname board.
I decided to test the noname '10MHz Turbo Board' first. Hooked up the power supply, inserted one of the HGC cards (you didn't think I would risk my EGA card, did you? ;)) and hooked up the monitor (actually, I am using a RGBtoHDMI converter, it's genious).
Flicked the switch, and yes, there was the boot up message from the BIOS! But 5 seconds later, a tantalum capacitor decided it had enough of life and dramatically blew itself up.
Ok. That board was for later, it can be repaired. So I switched to the Fujitech and did the same setup, and it showed its own boot up message while deciding that life was worth it and did not blow up anything. So Fujitech it was.
I had acquired that Fujitech board some 30 years earlier, and had replaced the BIOS on it with a Phoenix BIOS. But I thought it might be a good idea to do a quick Google to see if there might be any better BIOS by now.
So, I stumbled on the Super PC/Turbo XT BIOS for Intel 8088 or NEC "V20" motherboards (yes, sic). Check out the Github repository here: Super PC/Turbo XT BIOS. This BIOS is nice. And there are also extension roms for HD floppy support, XT-IDE drive support and BASIC. Cheers for Ya'akov Miles and Jon Petrosky!
So now the scene was set. I burned the new BIOS rom. Stuck the BIOS in the Fujitech. This time I figured it was safe to stick the EGA card in it, connected monitor, keyboard and power supply again, and flicked the switch. And I was met with a colorful boot up message.
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| Yep, that's me in the background |
Floppy drive and floppies
Next step was to connect the floppy controller with one of the 3.5" 1.44MB drives. So I did, started the computer, and lo and behold, the drive led turned on and after a few seconds the computer asked me to Insert BOOT disk in A: and Press any key when ready.
So, I needed to find some 720KB MS-Dos boot disks. I wasn't sure which MS-Dos version to use, so I decided on MS-Dos 3.31. You can download images from WinWorld.
Finding 720KB floppies proved impossible (I had used them all for my Amiga), but as the floppy drives was a 1.44MB drive anyway, I figured that it would work quite well if I took a 1.44MB floppy and taped off the identification hole. So I did, then formatted a floppy to 720KB in my main computer and wrote the image to it, and all went well.
As a sidenote: my main computer is a Macbook, and it's using a Samsung USB floppy drive. I used Balena Etcher to write the images to the floppies.
Inserting the floppy and pressing the Any key booted up the computer nicely. Great! Halfway there! All that was left was mass storage, let's try the SCSI card!
First attempt
I connected the Seagate ST12400 drive to the SCSI card and booted up. That ST12400 makes such a cool sound when it boots up!
The SCSI bios bootup message was shown, and after a second it mentioned 'Waiting for Drive Ready.". Yess! And a few seconds later it mentioned "Unknown SCSI Drive', and the computer continued booting. NO!!!
After the computer finished booting, I checked if there was a 'C:' drive, but nope. Running fdisk didn't help either, it just said 'No fixed disks found'. Dead end.
So, what now? Hoping that the BIOS would have some kind of setup functionality like the 8-bit MFM drive controllers, I fired up 'debux.exe', checked where the BIOS was located (C800:0, where I expected it), and typed 'g=c800:5'. But the computer just hung there, nothing happened, clearly there was no setup software in the BIOS.
Not so Relax SCSI card
This SCSI card came with no documentation at all, and a Google search for Relax Technology Inc, or their SCSI Host Adapter came up blank. I think it's this company, which operates under a different name now.
But at bootup time, the card shows the boot message, and that gave more clues.
Trantor Systems, Ltd... That's a well known name in the world of SCSI. So, could this card be a Trantor card that was rebadged for Relax Technology? But which one?
A Google image search gave a solution, but in an unexpected way. It returned with a link to a card that was exactly like mine, on EBay. But on EBay, the card was listed as a 'NEC CDXT001'. And there was another same card on EBay, listed as 'NEC CD-XT001A'.
So, the next step was to search for 'NEC CDXT001'. No hit. 'NEC CD-XT001' then? And bingo, there was the Vintage Computer Federation Forums with a post from 2009 asking some help with a 'Trantor T100/NEC DC-XT001'. And a few lines down in the Google search results there was a link to stason.org with more info on a 'T100 (CD-XT001)' card, including the dip switch settings. My card turned out to be a Trantor T100 card!
The next search for 'Trantor T100' led to theretroweb, who also had a bit of information in their database.
But it was all very sparse. And none of the info mentions any BIOS, while my card had one. Nobody had apparently ever seen the BIOS.
But the forum post on VCFED gave me the clue that finally got me some results. It mentions 'MA100.SYS', 'TSCSI.SYS', 'TLSCDR.SYS', and 'SCSITEST'. And with a Google search for 'trantor MA100.SYS' came up with a link to ftp.oldskool.org, where I found that file and the other mentioned files as well. That seemed to be a driver pack. So I fired up my ftp and quickly 'mgot' all the files. The files turn out to be a driver pack named 'Trantor SCSIWorks! version 1.1'. Now we might be in business!
UNRELAXED SCSI card 🥺
The next thing I did was set up the dip switches. None of them were in the right place, according to the T100 documentation. I wanted to set it up as default as possible, so here we went:
| SW1/1 | Boot rom enable | ON |
| SW1/2, SW1/3 | BIOS at C800 | ON, ON |
| SW1/4 | Parity enabled | ON |
| SW1/5, SW1/6 | I/O address at 320h | ON, ON |
Basically all switches to ON.
With the jumpers, I configured the device to use DMA channel 1, and IRQ 5. Just because.
After booting, I ran 'SCSITEST', to see what it would tell me. But all it told me is that it couldn't find a host adapter. Maybe I should install the drivers first. I dug up and connected a second 3.5" drive to drive controller so as to not have to switch floppies. And with the MS-DOS 3.3 boot disk in a: and the SCSIWorks! disk in drive b:, I ran 'HDINSTALLER'.
Good, at least something is working! Install Distribution Software gives me a new menu.
No problem, I can enter the adapter and interrupt myself. So reboot and run HDINSTALL again. This time manually choosing a T100 adapter and IRQ 5, and Continue. After asking me for my boot drive, it showed me a nice page with all the changes it was going to make.
I decided to proceed, and found that the installer is really great, it told me everything that it's doing (note that I had the SCWorks! files in a folder 't100').
A quick reboot later, disappointment strikes again.
No adapter found. Why? The adapter's BIOS finds the harddisk, even though it doesn't know it. So apparently it's communicating with the drive, and the adapter must be OKish enough to do that.
So, maybe the dip switches? The BIOS is loaded, so the BIOS address is fine. The IRQ? Well, the system didn't even load the driver, so that's probably not it either. Drive parity? Has nothing to do with the adapter's findability.
So, maybe the I/O address? Let's change to 32Ch.
| SW1/5, SW1/6 | I/O address at 32Ch | OFF, OFF |
Restarted the computer, and to my surprise suddenly there was no BIOS bootup message anymore..? And also, the MA100.SYS driver still did not find the host adapter. It seemed like things got worse instead of better.
I returned the dip switches, rebooted, and the BIOS was there again.
In a bid of helplessness, I decided to change the BIOS address to CA00h.
| SW1/2, SW1/3 | BIOS address at CA00h | ON, OFF |
After reboot, still no host adapter detected. I thought: "let's go radical" and changed the BIOS address to CE00h.
| SW1/2, SW1/3 | BIOS address at CE00h | OFF, OFF |
'No SCSI host adapters detected'. This was leading nowhere.
I then took up the idea of checking the images I found from the EBay listings, and set the dip switches to those settings. Maybe that would work.
Still 'No SCSI host adapters detected'. What if I switched off the BIOS? Let's do that, SW1/1 to off.
Rebooted. That's weird... I still saw the BIOS bootup message...
Conquering the SCSI card
...but hang on! The driver recognized the card! And the hard disk too! I win!
But there's the 'No TSCSI functions in use.' message, and no c: drive yet. So I wasn't there yet.
I ran SCSITEST first, and it found the host adapter and the drive as well, so that was good. Maybe the harddisk just needed to be formatted.
So I tried fdisk. But fdisk said 'No fixed disks present'.
The obvious next thing was to try TFORMAT, Trantor's own utility. And TFORMAT at least recognized the drive.
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| Whoo! 2 gig! |
But whoops... Foiled again! Drive too large...?
Noo! 2 gig!
TFORMAT gives the option to specify the heads/cylinders/sectors manually, by pressing ESC (I found out by accident, but later found it in the manual too). But TFORMAT does not let itself be fooled. Even if I entered fewer heads, cylinders and sectors, it would still tell me that the drive had too high a capacity. I did not have another smaller drive, so I was stuck at this point.
Another drive, another day
I needed to use a smaller drive, which I didn't have. That meant I had to ask some friends if they had one. And yes, one of my friends had a Conner CP3040A from an old battery-damaged-beyond-repair Macintosh LCII. So, that came my way.
While waiting for the drive to arrive, I scrounged the internet for even more information, found SCSIWorks version 1.2 and 1.3, where 1.2 still had support for the T100, but 1.3 not anymore.
I also went back to have a look the dip switches. The current settings worked unexplainably. For instance, the I/O address was reported as being 32Ch, while I had set the dip switches for I/O address 320h.
Also, with debug, I found the BIOS at address CE00:0000, while according to the current dip switches, it should be at address CC00:000. Puzzling...
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| My card's dip switch settings |
And then it hit me... It had been in my face all the time. On my card, the dip switch was mounted ROTATED 180 DEGREES!
EBay card dip switch settings
So the numbering is not 6, 5, 4, ..., 1 from left to right, but 1, 2, 3, ..., 6! And furthermore, ON is DOWN on my Relax card, while on the NEC CD-XT001 card ON is UP!
So, if for the EBay card, the dip switches were down-up-up-down-up-down, for my card they should be up-down-down-up-down-up. What a mindf*ck...
With the dip switches set as such, the BIOS was indeed disabled, and the MA100.SYS driver detected the host adapter at 328h. Good enough for me now, I had to wait for a smaller hard disk anyway.
A smaller drive driving driver progress
In time, the Connect CP3040A arrived, and I connected it immediately. And it was found and apparently working fine.
Fdisk still did not find anything that it could use. So next up was TFORMAT. That found the drive and I was able to partition it. Remembering that MS-DOS 3.30 doesn't allow partitions to be greater than 32MB, I wanted to make one 10MB partition and 1 with the remaining 30MB.
And again I ran into problems. This version 1.09 of TFORMAT seems to be buggy and I was not able to enter an ending cylinder of 513 without the app crashing. The huge sector number it provided came from out of thin air, as it had correctly found the number of heads to be 1 and the number of sectors to be 2052.
But I remembered that I was using SCSIWorks! version 1.1, and that in the past days I had found SCSIWorks! v1.2. So I copied its TFORMAT, which turned out to be version 2.02, and used that. That worked perfectly, and I was able to partition the drive properly.
A funny thing is that during partitioning, TFORMAT asks me if I want to make the first partition bootable. But it cannot ever boot without a BIOS!
Anyway, partitioning and formatting commenced and was successful. TFORMAT liked to hang up the computer after exiting, but a power cycle fixed that.
A few seconds later, I had volumes c: and d:! Success Is Mine!
Now I had usable mass storage. Except that I still had to boot from floppy...
I decided to enable the BIOS again and see if it would boot. But nope, no boot, the BIOS simply says: "Unknown SCSI drive." and ignores the drive. The BIOS apparently only supports certain drives.
But I was not going to leave it at that. What good is mass storage if you can't boot from it? If the BIOS doesn't recognize the drive, then what drives DOES it recognize? Maybe I could coax the BIOS into recognizing the CP3040A.
But, that is another long story, and will go in the next blog post... 😁
Leaves me to wrap things up a bit with a few links to software I used.
For anyone with a Relax Technology, a Trantor T100 or a NEC CD-XT001A SCSI Host Adapter, here is the SCSIWorks! software for it.
Note that I added SCSIWorks! version 1.3. However, that does not (officially) support the T100 anymore, Trantor dropped the required MA100.sys driver. But parts of it might be useful anyway.
Trantor SCSIWorks! version 1.1
Trantor SCSIWorks! version 1.2
Trantor SCSIWorks! version 1.3 (doesn't support the T100)
I have also dumped the BIOS. But something peculiar is going on. The SCSI BIOS is programmed in a 27128 eprom, while it would fit into a 2764 eprom. It is copied twice in the eprom. I have tried to program the BIOS in a 2764 eprom and use that, but that wasn't working for some reason. Hence, the bios file is 16KB of size.
Relax Technology/Trantor TSROM: SCSI BIOS Version 0.84
See you next time!
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