Text in Spanish
Repairing a 8088

   Who doesnít have nowadays an old PC XT?, this article goes to everyone who is interested in using this old computer to do something, maybe to play that old game that brings us good reminds, maybe for print old documents created in framework III when we were at school that we wonít miss forever.
   Obviously lots of people thought that ďitĒ can only be used as trash, and itís a logical thought nowadays, who wants a slow device, having what we have in todayís shops?. Still in this line of thought, to have a 8086/8088 as a hobby could be very interesting.
   A great mistake where many people falls talking about old computers is to think that it are useless. And certainly are useless for lots of tasks: canít be used to run latest Microsoft Office, canít be used to play latest Quake version, but its ďageĒ software is indeed usable, unfortunately usually we donít have it.
   If at this document point, you think that talking about PC XT is a useless time waste, then you are invited to stop reading it, but if you dare to plug that old PC you are welcomed.
   I donít want that you leave your actual computer alone and replace it with a PC XT, itíll be nonsense, but we could try to take the maximum advantage of  the PC XT, that surely abandoned in the loft donít have any use.
   Weíre going to follow a practical example for tunning the PC XT, itís based on a real case, that can many times be the same with the real old computer status.
 

IBM XT


 The Machine: IBM PC XT Model no. 5160 dated 1982 d.c.

   This computer is a classic IBM XT , probably it launched the PC to the fame (who would say), itís alias name is ďthe tankĒ and if you take it on your own hands and throw it down the stairway itís able to keep running. If someone had proved it Iíd like to be notified by e-mail.
   The first thing to do when we recover a computer like this from forgetfulness is to check humidity, if itís rusted you could see it looking at the computer case or the power supply. Anyway the first is to open the case , usually itís a desktop case, and you only have to remove some screws, take off the inner dust and watch what happens when you turn it on.
   In our case it seems to be in good conditions and it hasnít dust inside, once turned on we could see the memory count test, 5 seconds later a vertical line across the screen hangs the computer, that line goes on and off, a few moments later the screen goes black. The first sped to solve this is to make sure that the screen is working  ok. Weíll connect another screen to the computer, in this case happens the same.
   Then maybe itís caused by the video card a MDA type in our case. We install a CGA/Hercules and nothing at all on the screen. We unplug the floppy disks and the hard disk, checking for an electrical shortcut and tried again. The same. The point is to keep discarding parts, letís check the power supply, itís a bigger one AT type, luckily IBM this time used an standard suppy, weíll replace it by other new AT power supply bought at nowadays stores. Eureka it works!, we connect again the floppy disk and the hard drive. Turn on the computer again, and after the long computer 640Kb. memory test, it seems the hard drive have an operating system installed on, MS-Dos 3.20. 
 

Floppy disk


 

   Now itís time to load some of this old 5 ¼ floppy disks containing that wonderful game, letís insert disk on A:    DIR, oh no, error reading A: we try it some more times but nothing. Surely it have got dust, you can see it if when you extract the floppy disk it's dusted. If youíre lucky you will have got a cleaning disk, if itís not your case, may be using an air spray or blowing hard yourself could solve it, if not, a task that could take longer to do is to disassemble the floppy disc drive at all, clean it and assemble it again, this could be an interesting activity for all who likes to see the inner secrets of a disc drive, but you must wish it. In our case, we have another 360Kb drive, we plug it, test it again and works!
 

Monitors used


MS-DOS
Pctools System Info

 
 

  This is an example where all was very easy because we have replacement parts for all, some times we have to assemble two PC XT into one, with parts that works from one and from another. Somebody could be lucky and turn on the computer and have all working ok. The truth is that this last words is regular because as youíll know things manufactured long ago were dessingned for long duration, we couldnít say it today.