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