maxtherabbit wrote on 2021-06-12, 02:43:

rmay635703 wrote on 2021-06-12, 02:07:

I can clearly show you many period advertisements advertising 0 wait states
45-56ns system memory in their mid-range to upper range offerings with all sorts of cpus.

Can you, please? Because I certainly have seen them for up to 20MHz processor clocks, but not beyond

Neither have I. Nor have I seen any evidence that 50ns or faster 30pin SIMMs were ever available commercially. There may have been hand picked modules for bespoke systems but not that you or I could walk into a store or buy mail-order.

megatron-uk wrote on 2021-06-12, 07:56:

maxtherabbit wrote on 2021-06-12, 02:43:

rmay635703 wrote on 2021-06-12, 02:07:

I can clearly show you many period advertisements advertising 0 wait states
45-56ns system memory in their mid-range to upper range offerings with all sorts of cpus.

Can you, please? Because I certainly have seen them for up to 20MHz processor clocks, but not beyond

Neither have I. Nor have I seen any evidence that 50ns or faster 30pin SIMMs were ever available commercially. There may have been hand picked modules for bespoke systems but not that you or I could walk into a store or buy mail-order.

I don’t want to waste too much time but looking at the first 1991 magazine scan looky what I’ve found

Yet it's only 20MHz...

maxtherabbit wrote on 2021-06-13, 00:37:

Yet it's only 20MHz...

And 53ns

The Computer Shopper always listed 50ns ram at astronomical prices as well

So yes it existed in the day but as stated 1991 hit 50ns was invented and after that literally no one cared about zero wait states or memory speeds

I remember this ad too, only ran for 2 or 3 months, the 53ns stands out in my mind but ad was in color showing the ram sticks too.

Cheers,

Does this board support EMS/UMB? I see it has various shadow ram settings, so it should ...probably?

I guess if you ever bought one of those ZEOS 386SX-20s with 0WS memory, you'd be pretty much screwed if you wanted to add more RAM. You could either get ripped off by the dealer, or you could buy regular 60ns stuff and add a WS, killing your performance.

Anonymous Coward wrote on 2021-12-29, 08:07:

I guess if you ever bought one of those ZEOS 386SX-20s with 0WS memory, you'd be pretty much screwed if you wanted to add more RAM. You could either get ripped off by the deal, or you could buy regular 60ns stuff and add a WS, killing your performance.

Or you could not know better and overclock ram and get one of 3 scenarios
1. Can’t clear post
2. Unstable
3. Luck out

Back in those days the OEM would always tell you that only their aftermarket parts would work in their box.

I think I lucked out with a set of 4 1MB 30 pin 60 nanosecond SIMMs I got hold of mid 90s when I was still a bit green. Since I recall setting 0ws on a 486sx33 board at the time and then being puzzled by why I couldn't set 0ws on anything else after. They were DIL chips, but the entire module was very low profile. For some reason they were the cheapest set of 4x1 I could pick up at the time I needed them. I only regarded them as "ordinary" 1MBs at the time though so they didn't get specially saved and I don't know where they ended up.

I tried setting 0ws on a 386sx25 thinking man that’s so slow why couldn’t I set 0ws?

Box wouldn’t post after that and too stupid to disassemble and reset the cmos

Hi guys how are you? This is my first post.
I recently purchased the same motherboard M216 REV 1.2 without 286 BIOS and KEYBOARD BIOS. I found the 286 BIOS image here:http://chukaev.ru54.com/bios/2pcm001.zip
I am going to burn the image in a 27c512 EPROM.

Regarding the keyboard bios or keyboard controller I found that it is an Intel 8042 MCU. The 8742 is an eprom version of 8042.

Until now I was unable to find the firmware for it.

Edit: I finally found the 2 kbytes binary firmware of the IBM PC-AT KBC here: http://minuszerodegrees.net/rom/bin/ibm_15030 … motherboard.bin

It should be burn in a MCS-48 MCU IC 8742.

Regards,
Ariel

There is no need to mess with the KBC. Try a spare from any 286 386 486 board.

27c512 for the main BIOS is fine. You need to make sure to fill it with multiple copies if its bigger than the image file.