Rafal wrote on 2021-08-17, 19:49:Hi again, thank you very much for helping me out!I took your advice, but still no success :(
I've purchased a parity rams, put […]
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Hi again, thank you very much for helping me out!I took your advice, but still no success 🙁
I've purchased a parity rams, put them (sim1, sim1-2, sim1-4) - still 3 beeps.
I've also purchased a POST diagnostic card, and what's interesting I have a "100C" code, which according to manual means (in my own translation):
10 - The byte zised command to the keyboard controller has been stored. Next, generate the command to lock and unlock pins 23 and 24.
0C - The input buffer of keyboard contoller has been erased. Next, send the BAT command to the keyboard controller.
Discard the manual provided with the card. The card doesn't understand anything about the POST process, it just displays whatever code numbers are sent by the BIOS. Every BIOS manufacturer uses different codes. Sometimes, the codes get reorganized by major version updates even at the same manufacturer. Also some vendor-provided hooks in certain boards output extra POST codes, which you can't find in any list.
Your best choice is a comprehensive POST code list, e.g. the one at www.bioscentral.com. Checking the AMI BIOS subpage shows for old AMI BIOSes:
- 0C: System timer OK
- 0D: Referesh timer OK
- 10: Start 64K base memory test
Your card shows the last value on the left and the previous value on the right. So the computer is currently at the 64K base test, and the previous checkpoint was that the system timer is OK. The POST card model you use (which is very common, and I use it, too) can miss some POST codes if they are sent in quick succession, so possibly 0D was also sent but not caught by the card. The three beeps you are hearing "base 64K memory test failed" match up perfectly: The BIOS started the base memory test (POST code 10), found the memory to be bad, issues three beeps and halts the system.
As you now have (probably) good memory modules, and the BIOS still is unable to access that memory correctly, I guess your board has some hardware damage. Possibly it is a broken trace to memory on the board, most likely concerning the RAM address bits. Your board obviously can read the BIOS EPROM successfully (BIOS checksum check is before base 64K RAM check), and as the BIOS is 16 bit (a "high" ROM and a "low" ROM) on your board, this means the 16-bit data bus from the processor to the ROM works perfectly fine, as well as the addressing of the ROM. A stuck "chip select" line on the ROMs, having them interfere with memory data might also be the problem. If you are interested in hardware troubleshooting, please tell us about your experience and tools (e.g. a cheap multimeter or a digital scope).