Done... 4 x 1MB = 4MB, 45ns, FPM, Simm-30 Memory Modules are now available.

I also managed to beat my 386 overclocking record with 0WS at 51.2MHz.

Video:
https://www.youtube.com/watch?v=VNtnxc0_SG8

Lol! "1-chip simms". They are beautiful in their simplicity.

Yep and easy to build and test.
That is why these modules are cheaper.
The only thing missing is the parity function.

galanopu wrote on 2021-04-13, 11:56:

I also managed to beat my 386 overclocking record with 0WS at 51.2MHz.

Bro what? 50ns is barely fast enough to do zero wait at 25MHz

Those 50ns memories have page mode cycle in the 20ns range.

I've always wanted to get some super fast DRAM to run 0ws at 50MHz...are there any parts available to make 16MB versions?

If you mean 4 x 4M = 16MB. As I said in the video.
I will try to remake the 16MB ones and make more pieces this time.
The only problem is that I do not know the batch of the chips I will get will be.
Most top at 46-47 MHz with 0 WS. I can only guaranty this for the 16MB ones.
I always try to do the best I can with the shock I have.

If you mean 4 x 16M = 64MB.
Should be possible to make but not at these speeds.
Also probably a bit pointless as 386 boards do not support these.
and 486 M/Bs also have Simm-72.
I might do Simm-72 next (45ns FPM).

I did mean 4 x16MB = 64MB. If it couldn't be made at 40-50ns, there wouldn't be a point as 60ns is readily available.
There are definitely 486 boards that accept them. Though, admittedly it's more of a niche item.

What about making 72 pin Simms with these chips ? I have a 486 motherboard that can do 0ws on both reading and writing but even with 60ns simms, I'm limited and it doesn't take 30 pin Simms, only 72.

Yes exactly next goal is to make Simm-72s with these chips.
These will again be fast, but this is only possible at low capacities.
So probably 45ns, max 8MB per Simm module.

Deksor wrote on 2021-04-14, 14:30:

What about making 72 pin Simms with these chips ? I have a 486 motherboard that can do 0ws on both reading and writing but even with 60ns simms, I'm limited and it doesn't take 30 pin Simms, only 72.

I have a couple 30p to 72pin trees not sure if the adapter would add latency

I wanted to test these adapters.
I do not have one, should work.
There is some latency for sure.

I need also more experience with 486 M/Bs.
My 486 default does 0WS with 60ns modules.
Need to clock mode this too :p

Anonymous Coward wrote on 2021-04-14, 14:24:

I did mean 4 x16MB = 64MB. If it couldn't be made at 40-50ns, there wouldn't be a point as 60ns is readily available.
There are definitely 486 boards that accept them. Though, admittedly it's more of a niche item.

16MB 30pin simms are more of a curiosity, it's true. They don't work on older boards, and the newer board that do take them also accept 72 pin simms, which are usually available at a lower price points for the same capacity

While some people will no doubt want to get as much ram as possible on their 486, I feel that any value you get by adding more than 32MB of ram to a 486 is offset by the time you spend watching the POST RAM count each time the computer boots.

But I'd be really curious to see what kind of improved timings you can get with a high capacity , 1 chip 72 pin simm with 50ns FPM ram.

There are some older 486 boards that take 16mb Simms, but the don’t use budget chipsets. Many eisa boards can accept it.

Anonymous Coward wrote on 2021-04-17, 12:16:

There are some older 486 boards that take 16mb Simms, but the don’t use budget chipsets. Many eisa boards can accept it.

Find a 30pin board that supports double sided 32pin Simms and I will give you a cracker

If more boards than expected actually support them he could just make these Simms into 2 chip cards for 8mb Simms

I owned 2 PCs that stated support, a late PCCHIPS board that was made so late it shouldn’t have had 30p Simm slots and a compaq.

I didn’t have any 32pin Simms when I owned these machines

rmay635703 wrote on 2021-04-17, 13:48:

Find a 30pin board that supports double sided 32pin Simms and I will give you a cracker […]
Show full quote

Anonymous Coward wrote on 2021-04-17, 12:16:

There are some older 486 boards that take 16mb Simms, but the don’t use budget chipsets. Many eisa boards can accept it.

Find a 30pin board that supports double sided 32pin Simms and I will give you a cracker

If more boards than expected actually support them he could just make these Simms into 2 chip cards for 8mb Simms

I owned 2 PCs that stated support, a late PCCHIPS board that was made so late it shouldn’t have had 30p Simm slots and a compaq.

I didn’t have any 32pin Simms when I owned these machines

I don't thing 32-pin SIMMs were ever a thing. 30 and 72 are the standards.

This has been discussed before. I don't have the link to the other thread, but 32-pin SIMMs were actually a thing. Apparently all but the two edge pins line up with the ones on 30-pin SIMM slots, and there is at least some degree of compatibility though I forget the specifics.

the macintosh SE/30 takes 16mb simms and there is a reasonable market for them

the pvi486sp3 only has 2x 72 pin simm slots, so 8mb in each isn't enough IMO

I have a PC-Chips M326 mobo with 486DLC and 4c87 coprocessor and 8x1mb ram modules. The fastest setting for stable boot is 1WS. Could i possibly go to 0WS with your custom modules?

Every motherboard behaves in a different way.
Some stress the memory more.
Now 0WS at 40Mhz are easily achievable with the M326 and any good memory modules like these.
This is the M/B I mainly use. You can check my video on that:
https://youtu.be/VNtnxc0_SG8
Now the effect of 0WS vs 1WS on the 486DLC is not that big (256KB L2):
https://youtu.be/1q4v_E_vKAI