Anonymous Coward wrote on 2020-12-27, 01:45:

pentiumspeed wrote on 2020-12-26, 17:19:

Minimum timing is 100ns for 10MHz 286, 12MHz to 25MHz means 80ns. […]
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Minimum timing is 100ns for 10MHz 286, 12MHz to 25MHz means 80ns.

The 200ns to 120ns were appropriate for 8088/8086 boards.

Get another set of memory at least 80ns for your 386, but 486 really prefers 70ns for best timings.

Cheers,

Fast 286s were sold with 100ns RAM, they just used wait states, which were common practice at the time.
Have you ever seen an original 6MHz IBM AT? I could be remembering wrong, but I think those used 250ns DIP RAMs.

Yes ! I had a old PGA 6Mhz 286AT mostly all TTL Gigantic board once long ago and it had 180 or 200nS DIPS iirc.
Was the worst board in my collection...Hence the "I had", it was not worth saving even for histerical purposes 😀

Horun wrote on 2020-12-27, 02:29:

Anonymous Coward wrote on 2020-12-27, 01:45:

pentiumspeed wrote on 2020-12-26, 17:19:

Minimum timing is 100ns for 10MHz 286, 12MHz to 25MHz means 80ns. […]
Show full quote

Minimum timing is 100ns for 10MHz 286, 12MHz to 25MHz means 80ns.

The 200ns to 120ns were appropriate for 8088/8086 boards.

Get another set of memory at least 80ns for your 386, but 486 really prefers 70ns for best timings.

Cheers,

Fast 286s were sold with 100ns RAM, they just used wait states, which were common practice at the time.
Have you ever seen an original 6MHz IBM AT? I could be remembering wrong, but I think those used 250ns DIP RAMs.

Yes ! I had a old PGA 6Mhz 286AT mostly all TTL Gigantic board once long ago and it had 180 or 200nS DIPS iirc.
Was the worst board in my collection...Hence the "I had", it was not worth saving even for histerical purposes 😀

In the dark times (1997)
I salvaged a 4mhz-286 non-ibm compatible from the scrapper but could never get the motherboard to post or bring up video ended up re-scrapping it a few years later when I found the miniscribe drive was also dead as a door nail

In hindsight unfortunate

IBM AT boards of three types, had around 150ns-120ns ram typically.

PS/2 50 had 120ns 1ws

PS/2 50Z ran 10MHz used 100ns for 0ws.

I had these boards at one point and knows this.

Cheers,

pentiumspeed wrote on 2020-12-27, 03:00:

IBM AT boards of three types, had around 150ns-120ns ram typically. […]
Show full quote

IBM AT boards of three types, had around 150ns-120ns ram typically.

PS/2 50 had 120ns 1ws

PS/2 50Z ran 10MHz used 100ns for 0ws.

I had these boards at one point and knows this.

Cheers,

IIRC the IBM 30 pin PS/2 simms are not compatible with other clone systems either. And vise versa without out modification.

Actually only one. PS/2 8550 up to pair of 512K simms for total of 1MB, some of them used right and left handed simms that has square aluminum cans.
This is one of handed pair:
https://www.google.com/search?q=ibm+512K+simm … =IFGFri7UZJ3utM

Not the 50Z which takes one 72pin dimm which is standard DIMMs with IBM type presence jumpers set. FYI: presence pinout are same for IBM and clones yet jumpers are different between standard and IBM type just reset the standard 1MB or 2MB DIMM presence jumpers to work in this PS/2 computers, requires easy soldering to move the SMD jumpers.

Cheers,

pentiumspeed wrote on 2020-12-27, 03:00:

IBM AT boards of three types, had around 150ns-120ns ram typically.

I had these boards at one point and knows this.

Cheers,

Well, you're at least correct about 150ns. I got confused because the piggybacked ICs had "250" in their part number.

Apparently these are rated for 150ns.

However, I have never seen 120ns from the factory in any of the ones I've owned (Type 1-3, and XT 286)