Pics please 😎

No pics no fun! I love to see XT systems in their original cases.

Looking forward to seeing pics. 😀

Cool story. I think it's amazing that your parents managed to keep this computer for so long instead of getting rid of it like so many of us did. Hope you have fun restoring it and please post pics!

Awesome and an interesting story! Pictures, please! 😁
Only had an 8088 laptop so far, but my dad once had an PC1512 which I think had an NEC V30.
He was usin' it for all kind of business stuff (you know, such as dBase, Clipper, Turbo Pascal).
When I asked him about those old computers, he often told me about the whole CP/M era and how he ran an public domain program named Z80mu.
So I'm curious, did you run Nice22 on it,too ? I heard it can make use of NEC's 8080 emulation mode!
Never seen that myself, but I always wondered how good that 8080 mode is and if it can z80 code, aswell..
Would be cool to be able to play all that old games, like Zork or Adventure natively and in their original form. 😎

Jo22 wrote:

So I'm curious, did you run Nice22 on it,too ? I heard it can make use of NEC's 8080 emulation mode!
Never seen that myself, but I always wondered how good that 8080 mode is and if it can z80 code, aswell..
Would be cool to be able to play all that old games, like Zork or Adventure natively and in their original form. 😎

Funny you mention that...

That seems like a nice system, I also want to see some pictues.

Adding a VGA card (or a CGA/EGA card if you have a suitable monitor) is probably not a bad idea even if amber monochrome screens are really nice for text.

carlostex wrote:

Funny you mention that...

Oh, wow! Haven't seen that before, seriously. Anyway, nice pix! ^^

Skyscraper wrote:

That seems like a nice system, I also want to see some pictues.

Adding a VGA card (or a CGA/EGA card if you have a suitable monitor) is probably not a bad idea even if amber monochrome screens are really nice for text.

Yup, that wouldn't be bad. But Hercules is fine, too. It has those hires graphics some games look better in.
For example, Zeliard looks sharper on Hercules or EGA (eventhough not as colourful and with stripes).
Please don't hurt me, but for VGA an old Trident 8900 would fit quite well here! 😉
It's mode utility can switch the card to more or less native CGA (incl. alternate colour palette), EGA or Hercules (well, half mode at least).
Composite CGA and an oldschool video monitor, like a Commodore 1702 would also be a nice choice.
Or even better, some of those green data displays with vbs input from the 70s. Anyway, it's Half-Saints project, so he should do it the way he likes it.

great story, needs more pics though 😁
I would't upgrade it to anything personally, it's quite awesome to have your first pc with all it's parts. Maybe change the failing HDD or add an adlib but the rest should remain the same 😀

I had a car accident on april the 2nd and yesterday was my first day back at work so I was very busy these two days. Tomorrow is a national holiday so maybe I'll find the time to take some pictures 😀

As for the planned upgrades, I'm not yet sure what I want to do with the machine. I already ordered an XT-IDE CF adapter and I have an 8-bit sound card to test with the XT. I'll see, if I can run Hercules and VGA at the same time. I'm thinking of keeping it completely stock with the addition of a CF card and LPT network adapter. After all, what's the point of getting an XT-IDE adapter, if I'm not gonna use it? 😀

Half-Saint wrote:

I'll see, if I can run Hercules and VGA at the same time.

Theoretically this is possible, but note that Hercules has 64K of RAM, where the second 32K of that memory would collide with a CGA/EGA/VGA card.
On real Hercules cards this is solved by disabling the second 32K (I believe there is a jumper for that on the card). If you have a clone, it needs to be able to do this as well, to avoid issues.

* * * ADDED PHOTOS * * *

Inspected the innards today and the motherboard I installed years ago is an Octek FOX II 286 Rev. 3.4 sporting a 20MHz Harris chip. The battery has started to leak slightly and I regret not getting the system earlier. The hard drive still works but looks like I deleted all of my stuff from back then. A lot of it is still on 5.25" floppies I reckon.

It turns out the computer was bought in 1987 and the most recent files on the hard drive are from 1997. 10 years of use is not bad for such a dinosaur 😀 The hard drive is a huge 5.25" winchester drive and it is quite loud. I always liked the sounds that it made while reading/writing.

EDIT #1: I brought with me a small box of cards (see pictures) but I don't think all of them belong to the original setup. The only one that I'm 100% sure is the Hercules card as it has a custom ROM. The card with the battery is probably also original since the machine had a game port. Anyone have any ideas? There's already a controller inside the machine itself as well, plugged into the 286 motherboard.

EDIT #2: I think I figured it all out. The cards pictured were ALL part of the original setup. The MFM controller that's in the 286 is a 16-bit card so it couldn't have been used in the XT. There's also a dual serial card I probably used during my BBS days because of its 16450 UART. Does anyone know, if 16550 and 16450 are interchangeable?

Half-Saint wrote:

EDIT #2: I think I figured it all out. The cards pictured were ALL part of the original setup. The MFM controller that's in the 286 is a 16-bit card so it couldn't have been used in the XT. There's also a dual serial card I probably used during my BBS days because of its 16450 UART. Does anyone know, if 16550 and 16450 are interchangeable?

Hi, do you mean software or pin compatible ? I think they're both, but I don't know for sure.
I know that OS/2 is picky about which UART chip is installed (it emulates a 16550, so I think this one is preferred), but in a PC/XT this shouldn't matter.
Except maybe some early telecommunications programs from the 80s. They had routines built-in to circumvent certain bugs of the 8250..

I've found some good informations here, here and here.

Don't know if everything I put together down here is correct, though.:

8250 first UART. Works up to 9k6. 1byte buffer
8250A faster version. IRQ bug solved
8250B similar, IRQ bug brought back for compatibility
16450 introduced with PC/AT, up to 38k4. software compatible to 8250 (well, almost I think)
16550 (early) lacks 16byte FIFO (only has a 1byte buffer)
16550 has got a FIFO buffer (first in, first out) of 16 bytes. buggy. 115k2 bits or higher.
16550A common version, for fast modems. 28k and higher. Working FIFOs. sometimes called 16550AFN
16650 modern version, 32byte FIFO, XON/XOFF chars programmable, adds power managment
16750 has got a FIFO of 64 bytes for sending, and 56 bytes for receiving
16850 and 16C850 got 128-byte buffers. speed 460k8 or 1.5 mbps
16950 hi-tech version, found on PCIe cards.

More about D16950 can be read here.

Article Why do I need a 16550, 16650, 16750 or 16950 UART?

Technical specifications on the 16550

Hope this wasn't to much, I think a 16550 is fine for almost everything. Wouln't make sense if the pinout was completely different to a 16450.
If you can, install a socket on the card and put in a 16550. If there are slight modifications necessary, then this makes it easier. 😀

I did some googling on my own and found evidence of XT owners swapping their 8250 for 16550. 16550 is backwards compatible with 16450 and 8250 so there shouldn't be any issues. Both 8250 on my I/O card are socketed so swapping them wouldn't be much of a problem. Still, thanks for the effort, didn't know much about later UART chips 😀

great how you kept it, look forward to seeing how modern you go
This is my very 1st PC (Dx2-66) Osbone 486 DX2 66 VL-Bus (My 1st PC ever)

I replaced the floppy for a gotek but it just didn't look right so the original floppy is back in.
I cant bring myself to upgrade it either as then it wouldn't be the same PC. Despite having better CPU's, sound cards, and a working CD rom for it.
Also have the original 420MB hard drive with the setup as close to original as I can, but most of the time has a 6GB drive with later version of dos, and just the games I'm interested in.

Houston, we have a problem. I removed the 286 motherboard today and installed the XT board. As soon as I switched on the power, there was a loud bang, a spark and foul smell. Of course I turned it off immediately to inspect the damage. One of the red tantalums under the keyboard connector exploded (C8). I removed it and tried my luck again and this time the computer turned on but I got a "Keyboard Bad" error.

Another problem is that for the life of me I can't figure out where to plug all the case cables - keyboard lock in particular. I feel that this could be the problem also. None of the connectors are labeled and none have three pins like the keyboard lock case connector. Tried looking online with no luck.

EDIT: I found the schematics here: http://stason.org/TULARC/pc/motherboards/U/UN … DES-RIS-TB.html

I was able to connect everything except the keylock so I used a jumper on JP3 and now the keyboard works.

Can't connect the floppy drive because I don't have the correct cable and will have to look for it. The hard drive is detected as unformatted and the controller wants to format it. I was able to boot from this same HDD on a 286 using a 16-bit WDC controller so what gives?

Um, I dont't know for sure, but some 16Bit controllers from the WD100X family don't come with a BIOS built-in.
I think they rely on the systems BIOS to provide drive geometry.
But you are using a normal 8bit card, so it should be possible to access the controller's BIOS.

Did you try this ?

DEBUG (return)
g=c800:5 (return)

I've found this at some vintage computer's forum.

Sorry, if if I told you something obvious you already know.

Maybe another cause is the recording mechanism, one controller uses RLL another one MFM.
Some fixed disk support both of them. They aren very smart, afterall.

In any case, I'm glad you were able to fix the mainboard. 😀

Jo22 wrote:

Did you try this ?

DEBUG (return)
g=c800:5 (return)

Nope, can't boot the system at all right now. I'd need to be able to get into DOS, to run DEBUG. Did some reading on the forum link that you provided and it looks like that command would run the formatting utility from the controller's BIOS. I'd like to avoid formatting the drive, if possible.

The problem is that the original controller that was used with this hard drive sees the hard drive but wants to format it instead of booting off of it. I don't understand why.

I might have to move the HDD to another system, copy data off of it and then perform a low-level format on the XT. Crap.

Oh, crap. The only idea I have left is booting of from a newtwork card.
Do you have any 3COM cards laying around ? They can be programmed to boot from LAN.
Doing so requires a DOS utility, which can be found online. I think it was part of a service or drivers disk.

Edit: I forgot, it is possible to use an 8bit controller in a PC/AT computer. Did this myself a few years ago,
when I got a filecard (aka hardcard). In fact, it was a 586 computer. The only odd thing is, you can't boot from your IDE drive anymore.
The WD1003's BIOS totally takes control over the boot sequence (the original PC didn't have a CMOS, so this makes sense).
Maybe you're still able to access the IDE drive as D (if the DOS on the MFM/RLL drives can handle the size -> 32MB partition limit of DOS 3.xx).