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PC Chips 286 M216 Motherboard

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Reply 40 of 56, by megatron-uk

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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.

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Reply 41 of 56, by rmay635703

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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

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Reply 42 of 56, by maxtherabbit

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Yet it's only 20MHz...

Reply 43 of 56, by rmay635703

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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

Reply 44 of 56, by pentiumspeed

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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,

Great Northern aka Canada.

Reply 45 of 56, by ltning

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

The Floppy Museum - on a floppy, on a 286: http://floppy.museum
286-24/4MB/ET4kW32/GUS+SBPro2
386DX-40/20MB/CL5434 ISA/GUSExtreme
486BL-100/32MB/ET4kW32p VLB/GUSPnP/AWELegacy

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Reply 46 of 56, by Anonymous Coward

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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.

Last edited by Anonymous Coward on 2021-12-30, 00:35. Edited 1 time in total.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 47 of 56, by rmay635703

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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.

Reply 48 of 56, by BitWrangler

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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.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 49 of 56, by rmay635703

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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

Reply 50 of 56, by abrunetto

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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

Reply 51 of 56, by Predator99

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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.

Reply 52 of 56, by sparky4

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i have 2 of these boards and one of the only detects 4 mb of ram while the other one detects 16 mb of ram... whats going on here?

wwww

Reply 53 of 56, by sparky4

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this board only sees 4mb out of 16 when i have another board which needs work can see all of the 16 mb i installed on it... somethoing is going on and i dont like it

wwww

Reply 54 of 56, by sparky4

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okay i noticed there is missing parts and a jumper missing on the 2nd board compared to the 1st board
1st 2 images are the 1st board and the 3rdimage is the 2nd board

i am trying to get the 2nd board to detect 16mb of ram

wwww

Reply 55 of 56, by megatron-uk

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That looks like it is just an oscillator - it's marked as 32mhz ... I am guessing it's a 16MHz 286 that is installed?

Some 286 boards have more than one oscillators as they allow the CPU and fpu to run at different rates. It's possible that the second clock was not fitted to your later board as a cost saving measure.

Should not have anything to do with the memory support (or lack of).

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https://www.target-earth.net

Reply 56 of 56, by rmay635703

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megatron-uk wrote on 2024-07-17, 19:52:

That looks like it is just an oscillator - it's marked as 32mhz ... I am guessing it's a 16MHz 286 that is installed?

Some 286 boards have more than one oscillators as they allow the CPU and fpu to run at different rates. It's possible that the second clock was not fitted to your later board as a cost saving measure.

Should not have anything to do with the memory support (or lack of).

That is correct. There were a few oddball machines that divided the ISA/Floppy and CPU Clock from 1 oscillator like my Tandy 1000rlx and its 40mhz oscillator with a 10mhz cpu.

I’ve often wondered why there was usually a discrepancy in the oscillator used.

My Vintage “12mhz” photo computer was marketed as 12mhz but the oscillator is actually 25mhz which is 12.5mhz. The CPU used seems to be spec’d for 12.5 mhz for some reason.

I had the same experience that some 16mhz machines actually had a 33.xx mhz oscillator instead of 32mhz.

Not sure if this was a minor overclock or if it was in spec considering 8.33mhz was a very common ISA bus speed.