IBM XT 1801 Error...5161 Expansion Unit?

[Compgeke]

I've noticed recently that my XT is giving an 1801 error at startup, saying the expansion unit isn't working. The odd part is I don't have an expansion unit, or even a card for one.

The motherboard is a 64-256 KB and the installed cards are: VGA card, AST Six Pack Plus, NE2000 clone network card, Xebec hard drive controller, floppy controller and a 286 upgrade card, going left to right when sitting at the front of the system, with the 3rd from the left empty.

Anyone have any idea why I would get an error for non-existent stuff?

 

[modem7]

The 5160 POST determines the presence of the extender card for the 5161 by writing/reading to I/O port 210h.
Your NE2000 clone card, for example, may be set at I/O base address 200h, occupying subsequent I/O addresses, one of which is 210h.
Try pulling that card, seeing if the 1801 disappears on next power on.

 

[Compgeke]

Unfortunately that wasn't the magic fix, so tomorrow I'll start pulling cards one by one until I find the car that's causing the problem.

 

[Shadow Lord]

It could also be something completely unrelated. I was getting a 1790 error on a 5170 after tinkering with it. The 1790 is supposed to be a a disk error. I thought my HDD was hosed but it turned out to be the controller that was bad. I had broken off a resistor on it.

 

[modem7]

I was getting a 1790 error on a 5170 after tinkering with it. The 1790 is supposed to be a a disk error.

1700 series errors are not 'hard drive' errors per se, but errors related to the hard drive system.

Even then, a 1700 series error doesn't mean that the cause is restricted to only drive/controller/cabling. For example, lack of -12V from a clone power supply, one that generates a 'fake' power good signal, will result in a 1790 error (the IBM 5170's controller needs -12V in order to read hard drive data).