Page 1 of 1

IBM PC XT

PostPosted: Mon Dec 09, 2013 9:49 am
by SpidersWeb
http://www.trademe.co.nz/a.aspx?id=672197516

If you're interested, you'd need to confirm details with seller but it appears it's the later 'enhanced' model - 20Mb option/640Kb on board/half height devices.
Just wanted to mention that because it's potentially closer to original than it appears.

"Wont go when motherboard is connected"
yey tantalum capacitors (easy to find fault, they're usually 1 of about 5)

Re: IBM PC XT

PostPosted: Mon Dec 09, 2013 11:40 am
by tezza
Yes, I'm eyeing this one up myself. The board will make a good spare for my existing XT.

Re: IBM PC XT

PostPosted: Sun Dec 15, 2013 10:08 pm
by tezza
Got the machine for $32. I was happy to spend that just to get some spare parts.

Picked it up today. Case in not as bad as it looks and I think with a bit of elbow grease I could clean it up. Actually there was bonus material..things I did have for my collection XT. A badged IBM full height hard disk drive cover and a genuine IBM 1/2 height floppy drive. A 8087 match co-processor. There was an async card too, which I can put in my 5150 to replace the faulty one there.

Otherwise there was the usual, 20MB full height drive, Mono video/parallel port 1/2 size board (I'm assuming herc). one floppy drive. 512k onboard.

Tonight I started the process of finding out what works and what doesn't. Started with the motherboard. Yes indeed Jono, a shorted cap on the 12v line was the problem here. However there was more. Fixing the cap left me with a firing PSU but still a seemingly dead motherboard. The problem turned out to be a faulty RAM chip in bank 0. Discovered by substitution.

Tomorrow I'll check out the drives.

Re: IBM PC XT

PostPosted: Mon Dec 16, 2013 4:37 pm
by SpidersWeb
Excellent.
Yeah bank 0 can be a pain when it goes wrong, not the easiest diagnosing with no obvious symptoms. Glad you got it sorted quickly.

Re: IBM PC XT

PostPosted: Mon Dec 16, 2013 9:39 pm
by tezza
* Attached floppy drive --> cleaned heads ---> works just fine
* Hard disk ---> Nothing. Gave the disk a low-level format using IBM Advanced diagnostic disk. then partitioned with FDISK
*Formatted and installed PC-DOS 3.2

Hard disk now fine and I have a second fully working system IBM XT

Re: IBM PC XT

PostPosted: Tue Dec 17, 2013 7:05 am
by SpidersWeb
Awesome. PC DOS 3.2 was a good pick.

I had a feeling you might've needed an LLF, my sample size isn't huge so maybe it's a fluke, but of all the XT based machines I've had arrive - if a Seagate ST225 (that specific model) was fitted, it always needed an LLF on arrival or within a few minutes of use. Good drives though.

Re: IBM PC XT

PostPosted: Tue Dec 17, 2013 7:36 am
by tezza
It is indeed a Seagate ST255. :)

I'm please with this machine because it has a lot of the genuine IBM trimmings that my other one doesn't. Like the genuine IBM full sized HD faceplate, floppy drive and disk controllers. An old-fashion async card. The 8087 maths co-processor. Some mixing and matching should see my XT show machine look more authentic.

Worth the $32.