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10Mhz XT to fast for memory card?

R

Robin4

Veteran Member
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Sep 25, 2011
Messages
529
I found this page from an XT motherboard manual:

tofastformellow.jpg
It says: Do not use RAM memory on an expension card because its design may not be compatible with 10Mhz CPU at access time.

This is written on a page of the PIM-TB10-Z motherboard manual.


I like to know if this is true.. And what advise can i get, when i want to use a memory card in an XT 10Mhz system.
Or isnt this always true, but sometime can happen that it just wont want to work because of timing issues..
 
I think what they are saying/suggesting is:
Be aware that there are RAM cards that are incompatible with the PIM-TB10-Z running at 10 MHz. Therefore, to get 640 KB total conventional memory, you are best to fully populate the motherboard RAM sockets.

For some incompatible RAM cards, the answer may be to put in faster rated RAM chips. For other cards, that may not be enough. Some cards may have a switch/jumper that gets the CPU to add a wait state, and maybe that is an answer.
 
200ns or faster for 4.77MHz
150ns or faster for 8MHz
120ns or faster for 10MHz

However if your card is designed for slow speeds and has 74LSxxx chips, it may not work well even with 120ns DRAM.

If you get a new EMS card or UMB card from lo-tech design, they'll work fine at 10MHz, 12MHz, probably higher. They use speedy SRAM from Pentium era.
 
Last edited:
dhau said:
200ns or faster for 4.77MHz
150ns or faster for 8MHz
120ns or faster for 10MHz

However if your card is designed for slow speeds and has 74LSxxx chips, it may not work well even with 120ns DRAM.

If you get a new EMS card or UMB card from lo-tech design, they'll work fine at 10MHz, 12MHz, probably higher. They use speedy SRAM from Pentium era.
Click to expand...
250ns works fine with 4.77MHz, but the faster speeds do need those faster RAM chips.
 
When I saw that page of your motherboard, I knew it looked very familiar. Here is the manual for my XT Turbo Clone motherboard with slightly different writing. It is a TXM10-II (M8031) supposedly from "Auva Computer Inc", despite my manual not having any such references to it. (TXM10-II (M8031) Funny how obscure and similar to each other these XT clones were back in the the day. This was originally bought by my father in 1988 in California and I just got it back to working order. It is still running along with the original ST-225 MFM drive with no bad sectors, a NEC V20 Processor, and a Intel 8087 co-processor.

TXM10-II_ManualCover.jpgTXM10-II_Page_1.jpg
 
nilo said:
When I saw that page of your motherboard, I knew it looked very familiar. Here is the manual for my XT Turbo Clone motherboard with slightly different writing. It is a TXM10-II (M8031) supposedly from "Auva Computer Inc", despite my manual not having any such references to it. (TXM10-II (M8031) Funny how obscure and similar to each other these XT clones were back in the the day. This was originally bought by my father in 1988 in California and I just got it back to working order. It is still running along with the original ST-225 MFM drive with no bad sectors, a NEC V20 Processor, and a Intel 8087 co-processor.

View attachment 1259456View attachment 1259457
Click to expand...


Is this manual anywhere for download?
 
This board is interesting, it's a 10MHz XT clone, but it has a conventional discrete chip design common in 8MHz Turbo XT boards. Is it just using later CMOS versions of chips from NEC/Toshiba and so can overclock to 10MHz?
 
nilo said:
It is a TXM10-II (M8031) supposedly from "Auva Computer Inc", despite my manual not having any such references to it.
Click to expand...
nilo said:
I've scanned my manual and it made it available at this link. Unfortunately, it was too large to attach here.
https://drive.google.com/file/d/1bsIkqMJZYGTCp2PN-81XOxW6efzDz9j-/view?usp=sharing
Click to expand...
Thanks.
I performed OCR on the PDF, then added the resulting PDF to the Auva section of [here], acknowledging you as the source.
 
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