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AOpen AP5VM, stuck at 64mb of RAM, why?

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RaptorZX3

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Quebec, Canada
i've been working to get this Pentium 200Mhz MMX setup working right when i'll have a case to put it in. But there's something bugging me.

This AP5VM board seem to work just fine, but while the AOpen and other websites say it support up to 128mb of RAM, i can't seem to have more than 64mb (2 x 32mb) installed on my EDO RAM slots (4).
And when trying to install a SDRAM (1 slot) stick, for example 64mb, it only seem to detect half of the memory (32mb on this one).

Any idea why it's doing this?
 
i believe i upgraded the BIOS to the latest version.

edit: i did the BIOS upgrade anyway, and tried more RAM on it, and it didn't helped.
 
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Try to track down a manual for this. It only works with a limited pool of memory types. For example, it will only accept 32 MB dual sided SIMMs that use 4MBx4 memory chips: 16 of them with parity variants adding another 8 4MBx1 chips. The highest capacity tested DIMM is 32 MB. The double sided DIMM using 4M by 4 chips (total capacity of 64MB) is specifically called out as not recommended. If you have SIMMS or DIMMS that use chips that aren't 1 bit or 4 bit wide, those will almost certainly not work.
 
all of the 32mb sticks i have here are double-sided, and the "new" 32mb ones i discovered have smaller chips and have a gap in the middle, they seem to be higher quality only by looking at them.

Here's a link to a ZIP file that contain the manual for this board:
http://us.aopen.com/downloadfile.aspx?RecNo=3637&Model=285&Section=8&DL=yes
i don't quite understand the memory explanation... (it's the last section in the HW manual)

Are they saying that in order for me to have 128mb, i have to use 2 x 32mb in Bank 0, and then 32mb of EDO in Bank 1 and 32mb in the SDRAM slot?
 
That board have the 430VX chipset? Might as well keep it at 64MB since its limited to caching that much.
 
RaptorZX3 said:
all of the 32mb sticks i have here are double-sided, and the "new" 32mb ones i discovered have smaller chips and have a gap in the middle, they seem to be higher quality only by looking at them.

Here's a link to a ZIP file that contain the manual for this board:
http://us.aopen.com/downloadfile.aspx?RecNo=3637&Model=285&Section=8&DL=yes
i don't quite understand the memory explanation... (it's the last section in the HW manual)

Are they saying that in order for me to have 128mb, i have to use 2 x 32mb in Bank 0, and then 32mb of EDO in Bank 1 and 32mb in the SDRAM slot?
Click to expand...

Matches the manuals I have. Unfortunately, while I have a VX system and an AOpen system, neither is the same as yours.

For 128 MB, the supported install would require 4 x 32MB SIMMs. If you have a 32MB DIMM, that will knock Bank 1 out of service and the best you can do is 96 MB with 2 x 32 MB SIMMs and 1 x 32 MB DIMM, unless you can find 64MB DIMM that works on that motherboard. The only way to get the use of both Bank 1 and the DIMM slot would be to install 16 MB (or smaller) sticks in each slot for a maximum of 112 MB because you need single sided RAM.

Unless you are very careful in finding the correct memory, don't bother with both SIMMs and DIMM having memory at the same time. Far too likely to burn out the memory because cheap VX boards don't correctly make sure that SIMM slots and DIMM slots get the appropriate voltages which are different.
 
so basically you're saying if i only have working EDO RAM up to 32mb on this board, when i install 2 x 32mb on Bank 0, Bank 1 won't work anymore, and i should just forget about using the SDRAM slot?

This is strange because the AOpen AP53 board DOES support 4 x 32mb EDO RAM, but i'm having problems with at least 2 of those boards lately, they keep on giving me blue screens and fatal errors while installing Windows.

I didn't know about this limitation because at the time (back in 1997 i think), on my Pentium 200 MMX, i had 16 or 32mb of RAM first, and then upgraded to 64mb, so i figured i had 4 x 16mb on the board, as they told me it's the maximum memory my board can take. I think they were aware the maximum was 128mb, but because of hardware limitations, it was 64mb
 
Remember AOpen was not a high end vendor and the maximum size RAM didn't exist when the board was manufactured. Don't be surprised when the system does not meet the maximums listed in the manual.

There might be a specific combination of brands and memory types that could work at 128 MB but without a AOpen tech note describing exactly how it happens you might never find it.
 
RaptorZX3 said:
so basically you're saying if i only have working EDO RAM up to 32mb on this board, when i install 2 x 32mb on Bank 0, Bank 1 won't work anymore, and i should just forget about using the SDRAM slot?

This is strange because the AOpen AP53 board DOES support 4 x 32mb EDO RAM, but i'm having problems with at least 2 of those boards lately, they keep on giving me blue screens and fatal errors while installing Windows.

I didn't know about this limitation because at the time (back in 1997 i think), on my Pentium 200 MMX, i had 16 or 32mb of RAM first, and then upgraded to 64mb, so i figured i had 4 x 16mb on the board, as they told me it's the maximum memory my board can take. I think they were aware the maximum was 128mb, but because of hardware limitations, it was 64mb
Click to expand...

Check Appendix B of your manual (FAQ). There's a brief remark about combining DIMM and SDRAM. According to the blurb, the voltages of both types must match for long term proper performance. Try running with only the SDRAM installed and see what happens. Tough problem, good luck.
 
so far i tried many 3DFX-related games: Hexen II, Quake, Quake 2, Pod Gold, and they all seem to work flawlessly (and most without big lags). I had to download an ISO of Pod Gold, since my genuine copy of Pod seem to have a bug in the installation where it only detect Voodoo1 cards (i have a Voodoo2 card). I tried bypassing this but first the colors were screwed up and then it crashed. Pod Gold have this installation issue fixed and work with all 3DFX cards i believe.


On another note, during next month, i might look for some old hardware, if i can have them anyway. And i may bring this Pentium 200MMX setup with me to put up on demo, this may convince even more the iMuseum's conservator to make that trade i want to do: i have old hardware i'm not even going to use, like tape drives and cassettes, and some old hardware that might not even work properly, so if it doesn't work, they can recycle them, while i can grab some hardware and test them at home to put old PCs together and making them work again.
 
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