First post, by Hezus
There's a thread on this forum about which PC you are still missing from your collection.. the one of which you hope comes up on your ebay notifications and you're the highest bidder. Well, this week I've picked up mine 😀
I've always been a sucker for XT class machines. I was given a Turbo XT 8088 more than 20 years ago and I've upgraded it in all kinds of ways. There is just something cool about them being so limited but still very usable. In more recent years I've acquired more unique XT's like the IBM Model 30 (a 8086 running at 8mhz) and more recently an Epson Equilty LT, with a 8086 (v30) running at 10 mhz. The 8088 was a very common machine, especially as a turbo XT. Everyone and their grandma's were building them. A real 8086 was far more expensive to produce. In the late 80's it just didn't make much sense to push the 8086 much further from a marketing standpoint. People who wanted to dish out cash for a premium machine could just buy a faster 286 or 386. And the 486 release was just around the corner in 1989. However, VTECH still saw some kind of profit margin in the 8086 and in 1988 the LASER XT/3 hit the market. And I'm happy it did 😀
This week I picked up my dream machine. I got it for a reasonable price and it came with all kinds of goodies: many original disks (plus a lot of less than legally obtained games), a Genius mouse, a dot matrix printer, lots of original documentation, a spare videocard (more on this later!) and of course the unit itself. The seller no longer owned the monitor and keyboard. But he still owned the original key for the lock on the front!
Just take a look at this beauty! The Laser XT/3 is such a glorious computer. For an XT, it has some really unique features like an LCD screen and a reset button. On the side it has a big red IBM styled power switch which is very satisfying to flip. The whole unit weighs a ton. There's so much metal in there it could start its own Iron Maiden cover band. Mine comes with a 720k 3.5" disk drive a 360k 5,25" disk drive and a 20 Mb harddrive. When I picked it up, I did a quick boot test and it seemed to post far enough for me to take it home. The unit was in pretty ok condition. It was of course dirty, some scratches and scuffs and some sticker residue but nothing major. Most noticable is the broken lever on the 5,25" disk drive, which can hopefully be replaced or fixed with some epoxy later.
I opened her up and on the inside I found the motherboard, videocard, hard drive controller and this I/O card, responsible for the floppy drive controller, serial/parallel/game ports and the Real Time Clock.
Oh boy.. and there we find the BANE of any retro computer collector: the VARTA barrel battery.
The battery had started leaking along the edge of the expansion board towards the ISA connector, corroding the connector and slot and some other areas of the motherboard.
Luckely, the traces around the affected areas are still alright. If this machine had spent another year or so in the attic, the damage would have been far worse. Seems I was just in time to save it.
I'm giving both board the white vinegar treatment and with some help of a toothbrush nearly all of the corrosion is gone. Sadly one pin on the ISA slot broke off in the process but the serial port connector breakout cable already takes up one of the slot spaces, so nothing is really lost.
With this picture of the motherboard it's time to see some more unique features that were not common for XT's. The system comes with 640kb of RAM but there is ample room for extra RAM chips, up to 1 mb. These can be allocated as EMS memory using a special driver. It takes 32x 41256 RAM chips to fill up the full 1 megs, which I do not have laying around and have become hard to find. Also very unusual is the heat sink on top of the CPU. It's just an U shaped piece of metal, glued on top of the chip. I've never seen anything like it before. It makes it impossible to read the branding on the chip, so it could be an original Intel, AMD or maybe even Siemens chip.
After this the system posted but none of the disk drives or ports were found. Something was clearly wrong with the I/O card. It seems it requires the Real Time Clock to be driven to function. Therefore I soldered on a 3v coin cell battery and the system was working properly!
Now that the battery issue has been resolved, it's time to clean up the case. Boy, this thing is dusty!
Next up is the big old XT power supply. Seems this is where all the dust bunnies go to sleep.
A lot of scrubbing later:
Then it was time to turn my attention towards the hard disk drive. The system came with a Seagate ST-255R 21mb drive along with the ST11R controller card.
It wasn't spinning up when I first got it, so I suspected the heads were stuck. I gently opened it up and gave the arm a little push and it came loose. After that the hard drive started spinning again and was succesfully detected by the controller card. I was able to format the drive but when the initialisation program ran the final test it always ended up crashing on cylinder 7, head 1. There seem to be some damage on the drive that it can't get past. I've tried adding this spot to the exclusion list at the start of the initialisation but it doesn't seem to skip the broken spot. The initialisation has to finish for the controller to copy the boot record. I tried SpinRite but it's not able to see the drive.
After a while I gave up on the drive, because I'm planning on using a far more convenient and reliable storage method: an IDE XT card with 256MB of CF memory.
The system originally came with this CGA/MDA videocard, but I do not own a a monitor for this 9 pin connector so it's not going to stay in the machine.
I'm in luck because the seller included a far more intesting card with the PC:
This is an ATI VIP (VGA IMPROVED PERFORMANCE) from 1987! This was their first VGA card before the Wonder series and has MDA/CGA/EGA and of course VGA capabilities. Note how the backplate has both 9 pin and 15 pin connectors for both type of monitors. It has 256kb of RAM and seems to be a later revision (BIOS 1.06 from 1988). This card (being such an early version) seems to have a more rudimentary implentation of VGA as it seems not to display correctly on more modern screens. As you can see here some of the text is slightly warped and in some other graphical modes it would display an 'out of range' message.
It seems to render everything just fine with more period correct hardware, though. This 14" Phillips PRO 3CM9809 seems to have no issues, apart from the horizontal orientation being a bit off (easily adjustable).
I'm glad to see that the videocard works well. I wasn't able to find much information of it online (no manuals or drivers/ultilities) so it must be quite rare.
Time for some upgrades! The obvious one is swapping out the 8086 CPU for a NEC V30.
I ran a quick benchmark using DOSBENCH (a nice program writting by Thandor). For reference, a regular 8086-2 running at stock 8 mhz will get a score of 18 points. The stock 8086 of the XT/3 scored 21 at 10 mhz. After I put in the V30 at 10 mhz I get a whopping 34 points! Quite the upgrade indeed and it makes it the fastest XT I own 😀
I also want some more interesting sounds than just the PC speaker, so I'm adding this Aztech Sound Galaxy card. Even though it's a 16 bit ISA card, it's fully 8 bit compatible. This should give me good Soundblaster Pro compatibility.
I also have this LIM card with 2 megs of EMS memory. It would have been a great addition but the system refuses to boot with it, complaining about a parity RAM issue. I guess there is a conflict because it probably expects the extra EMS memory mapped at those locations to on the motherboard instead of on an expansion card. So I'll have to leave this out of the system for now.
And here it is, all cleaned up and re-assembled, humming along with the Monkey Island opening theme!
Some ideas for future upgrades/fixes include:
- fixing the lever on the 5,25" disk drive
- swap low density drives for high density drives
- adding 1mb of EMS to the motherboard
- create a custom connector between the front HDD led and the XT IDE card
- add a network card
- fix up that printer and print something! 😁
So that's pretty much concludes my adventure! I finally got my dream computer and it was great bringing it back to life 😀 Hope you guys enjoyed my write-up here and love to hear comments and suggestions.
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