fsinan wrote on 2024-03-21, 17:36:
weedeewee wrote on 2024-02-09, 17:02:
Chkcpu wrote on 2024-02-08, 19:09:I agree, the official 2A4X5H03C BIOS should work fine and will indicate the actual L2 cache size. With the fake chips it will di […]
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I agree, the official 2A4X5H03C BIOS should work fine and will indicate the actual L2 cache size. With the fake chips it will display “None”. 😉
Because the 2A4X5000C only “fixes” the L2 cache size display to 256KB and doesn’t display any cache warning messages, I believe the 2A4X5H03C BIOS won’t complain about the fake L2 cache either.
Note that your BIOS is stored in a D27C010 128KB UV-EPROM chip and can’t be flashed.
Do you have an (E)EPROM programmer to program a new chip? It is usually easier to get a new 27C010 or equivalent (E)EPROM chip to program the official BIOS in, and keep the old BIOS chip as backup. It saves the hassle of erasing the old chip with UV-light first.
Cheers, Jan
Does the modified bios display the correct amount of cache when real cache is present, ie 64, 128, 256, 512K, or will it always display the fake 256K amount ?
Tried with 128K and 512K config, it shows the correct amount. But it hangs after "Starting MS-DOS"
Did you buy ISSI61C1024 chips? One of those has 128kB. Tons of it are sold on Ebay, they are sold in 10ns and 15ns. 10ns is 100% re-labelled, because it never existed in this speed rating, only 12, 15, 20ns.
I lately bought 20 pieces of it from a Chinese seller, 8 of it were dead.
Do you have TL866II-Plus programmer? It is has a SRAM test functionality.
So when you test it with that and it fails, then you know 100% that the chip is not working.
Unfortunately when a SRAM chip passes the test, you don't know really, if it works, because it does not test the timing of the chip.
But still you can easily filter out the completely broken ones, so it is a great speedup in finding good chips. So I have now 12 chips and have to check, whether they are really good or not, .....