TI Professional Computer (TIPC) Service Manual?

[Martin Peters]

Hi all!

David Gesswein:
> On Sat, May 28, 2016 at 10:42:29PM +0200, Martin Peters wrote:
> > I wanted to reactivate a TI Professional Computer (TIPC) and all I get
> > some seconds after powering it on is the message
> > 
> > "** system error ** 0004"
> > 
> > and a beep, lasting for about 2 seconds.
> > 
> > The TIPC is an early, not really compatible clone of the IBM PC 5150. I
> > wonder if I need to do some reengineering and/or disassembling or if
> > there is a service manual out there.
> > 
> I didn't find them in the technical reference but did find a list in the
> bios listing. If I read that correctly its interrupt or timers failed.
> Should be LED ON OFF OFF.

On Tuesday we replaced the 8253 and the 8259 and the error was still
there. Yesterday we took a closer look at the Maintenance Manual (s/o
sent me via PM on Wednesday) and the ROM-listing and it seems there is a
c&p-error in table 4-3 on page 4-9:

--- snip ---
              11111111  RAM - All bits failed
ON  OFF OFF   00000000  Interrupt controller failure
ON  OFF ON    00000001  Invalid interrupt
              00000010  NMI interrupt failure
              00000100  Timer interrupt failure
              00001000  FDC interrupt failure
--- snap ---

It should be:

--- snip ---
              11111111  RAM - All bits failed
ON  OFF OFF   00000000  Interrupt controller failure
              00000001  Invalid interrupt
              00000010  NMI interrupt failure
              00000100  Timer interrupt failure
              00001000  FDC interrupt failure
--- snap ---

We measure the additional diagnostic information on the onboard parallel
port and it turned out, it was a FDC interrupt failure. After replacing
the 1793 on the motherboard, the "** system error **  - 0004" message
was gone. \o/

Now, there is a "** keyboard error **  - 0010", sometimes "0011" and the
system boots to the DOS-Prompt of the installed MS-DOS 2.11 anyway, but
it is not possible to enter commands. The CAPS key works, so I think,
the keyboard is not damaged (at least not substantially). I think, the
transceiver components on the mainboard have blown. When I tested the TI
PC the first time (about two years ago), I suspected the "** system
error **  - 0004" to be a keyboard error, so I tested it with a
PC-keyboard (bad idea!), not knowing the TI PC being a very special
non-IBM-compatible device :-(

The 8251 is already replaced unsuccessfully, so the next step is to
change the receiver and transmitter on the mainboard. I'll report.

Greetings,
Martin