Introduction
Basics
Please read this first: IBM 5150 - Basics, for 5150 beginners (minuszerodegrees.net).
Update 03.01.2021:
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Since two days I have the problem with my IBM XT 5150 that the computer is dead as a doornail from one second to the other. At first it boots as usual and I can also work on it, but suddenly it is gone; the screen is frozen and no keystrokes are possible. Switch off the PC, wait at least 5 seconds, then switch it on, the power supply unit starts up but the mainboard seems to be dead. I then removed the plug-in cards and plugged in the Landmark diagnostic BIOS. Switch on and everything works again, absolutely no errors present! So I rebuilt the BIOS. A day later, everything repeated itself. What is this all about? My guess: When I changed the BIOS, I noticed that it was extremely loose in the socket. I have now installed the BIOS with an extra socket in the existing socket; both are now sitting properly tight. I hope I have now solved the problem.
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Figures
In the meantime I exchanged the i8088 for the NEC V20. So far I didn't see any problems. On the contrary, the NEC V20 even runs the terminal program TERM95 from the Norton Commander package! With the i8088, however, TERM95 cannot be started.
In contrast to the 5160, the 5150 has a cassette interface (2nd DIN plug from above). Below is the white relay for the cassette interface. You can hear it (slight crackling) when you copy files from/to the cassette recorder.
All banks (0-3 with parity) are completed with 4164 class RAM chips (150 ns, 128 cycle/2ms). The mainboard works perfectly.
- 8+1 / OKI M3764A-15 / 64 KByte (soldered)
- 8+1 / OKI M3764A-15 / 64 KByte
- 8+1 / OKI M3764A-15 / 64 KByte
- 8+1 / Fujitsu MB8264A-15 / 64 KByte
The tantalum capacitors are also working perfectly so far; round about 40 years.