🚀 go-pugleaf

In article <156@brl-tbd.ARPA>, turek@brl-tbd.ARPA (C. A. Turek ) writes:
> 
> 
> 
>  Here's a little gem for you hardware types. I have just spent a very
> exasperating day trying to upgrade a IBM PC-1 to handle a Bournulli Box
> and EGA. Both of these require the installation of the ROM BIOS upgrade
> for operation. So far nothing unusual.
> 
>  After pulling out the old rom, installing the new one, the system
> refused to do so much as a POST. The first sign of trouble was the lack
> of the cursor on the display. The system sets the screen to black, then
> NOTHING.
> 
> 
>  Both of these systems were purchased at the same time (from IBM) and are 
> configured as follows, any suggestions???
> 
> IBM PC w/64k system board, 8087 ( new 8088 also )
> Seattle 256k Ram Board w/1 serial port (COM 1)
> AST MEGA-Plus w/384k installed, 1 serial port, 1 parallel port, clock
> IBM EGA with 256k module
> IBM Enhanced Graphics Display
> Iomega  10+10 (This is the half card w/o boot rom) 2 10 meg drives
>  

I installed a new ROM in a similar system except I was installing a
fixed hard disk. The same thing happened to me. I discovered that
the Seattle card was the culprit. I forget which chip but it was a
74LS74. I replaced it with a 7474 I had laying around and everything
worked. This isn't exactly kosher but it works. 

DOES ANYBODY HAVE SCHEMATICS FOR THE SEATTLE CARD???

I've had this same problem happen to several cards especially when
installing a hard disk controller. I'd like to find out why but don't
want to take the time without a schematic.

In case anybody is interested, Moterola has a PROM that is pin
compatable with the ROMs used by IBM in the PC. I have used them
to upgrade PC-1 to PC-2 and also for diagnostic purposes. (Did you
know that the first set of boot diagnostics jump to the same location
when detecting an error. At that location is a HALT!!!!!. Really
helpful.)

The part number for the PROM is MCM68766C35. Hamilton-Avenet stocks
them (other places may have also, I have just dealt with Hamilton).
The price should be $12-15.

Dale Frye
Washington University in St. Louis
Computer Science Dept.
PO BOX 1045
St. Louis, Mo. 63130