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AP43 Motherboard Questions

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joekster

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Looking to get one for my "ultimate" 486 project. The motherboard manual states different things than the chipset datasheet. Anyone know the truth?

EDO DRAM: Manuals says no, but datasheet says yes (and shows better timings)
1MB Cache: Manual says no, but datasheet says yes
256MB RAM: Manual says no, but datasheet says yes (well actually 255MB)
 
I have never tried EDO, but since the FPM already runs at the tightest timings supported by the BIOS, I don't think you would gain anything even if it did work.
255 MB of RAM would be impossible to come up with using standard sized 72 pin simms and only 4 slots.
To be honest, 128MB would probably be enough for a 486 system. I have 64 MB in mine but I will be trying 128 MB soon.
 
I'm reasonably sure that EDO ram is backward-compatible with FPM ram.
As in, same pinout, voltage etc. Main difference is that EDO can accept new commands while it is still outputting data from the previous command.
If your chipset doesn't support EDO, it simply won't take advantage of this feature, but the EDO modules should still operate properly as FPM as far as I know.
I'm quite sure I put some EDO ram in old 486 FPM systems because I didn't have anything else lying around.
 
Scali said:
I'm reasonably sure that EDO ram is backward-compatible with FPM ram.
Click to expand...
My experience with 486-era motherboards says otherwise. At least some 486 boards must have FPM not EDO. I don't know about the one in question, though.
 
OK, so I took a chance and got the board - was pleasantly surprised:

1MB Cache: YES!, detected it - jumpers set to 256k/double bank
256MB RAM: YES!, 4x 64MB works fine. Board even works with 128MB SIMMs although only 1...
EDO: NO. Will not even post with EDO RAM., Tried a half-dozen different types...

So now the question is 128MB RAM with WB cache or 256MB RAM with WT cache???
Using a Pentium OverDrive which has a generously large 32kb L1 cache...

Opinions?
 
joekster said:
OK, so I took a chance and got the board - was pleasantly surprised:

1MB Cache: YES!, detected it - jumpers set to 256k/double bank
256MB RAM: YES!, 4x 64MB works fine. Board even works with 128MB SIMMs although only 1...
EDO: NO. Will not even post with EDO RAM., Tried a half-dozen different types...

So now the question is 128MB RAM with WB cache or 256MB RAM with WT cache???
Using a Pentium OverDrive which has a generously large 32kb L1 cache...

Opinions?
Click to expand...

Interesting. I like these findings.

Although I don't think you will need more than 128MB of RAM in a 486, WB is a waste of time.
WB CPU will gain some performance but WB L2 gains very little
 
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