IBM 5160 compatible?

[toncho11]

Hi,

Is it compatible with IBM 5160?

And can you disable the memory check?

[skiselev]

It should be compatible with IBM 5160, although one difficulty would be using large enough EPROM - 16 KiB, instead of 8 KiB one used in IBM 5160.

What memory check are you referring to?

[toncho11]

I mean disable the memory count at start up. On IBM 5160 there are two sockets U18 and U19. Would it work if written on both 50/50?

[skiselev]

Currently, it is possible to disable memory test on systems with BIOS configuration storage (RTC/Flash ROM), e.g. Micro 8088, Xi 8088, and NuXT. In this case the BIOS only tests the first 32 KiB. It is not that difficult to patch the BIOS to disable memory test on any other system, e.g., comment out call test_ram here, or add some kind of check here

I haven't tested it on an XT. But it should work.

Looking at the IBM XT memory layout, actually the ROM chips are or can be 32 KiB. So it should be enough to write the BIOS to the top (high 16 KiB) of the U18 EPROM.

[toncho11]

Thanks!

Maybe you can add a little bit more details on the front page for people with existing XT systems:

• required EPROM - 16 KiB
• are there any diagnostics features (messages, beeps, etc). When creating a BIOS one can decide which early tests to perform and how to indicate the error. For example if no test is performed the computer will block silently. If it prints an error message, but the video card is not working then it equals blocking silently
• some XT BIOSes are not compatible with "compatible" VGA cards as explained here: https://www.minuszerodegrees.net/supersoft_landmark/Supersoft%20Landmark%20ROM%20-%20VGA%20cards.htm

I like how the Olivetti M24 prints a list of the things it tested and which are OK