That is unfortunate indeed. Lets see if 4036yb handles it better for you.
Not surprised that aha-1522b did better than 1542c#.
Once you get the Advansys / SIIG controller, it should move the needle quite a bit.

Btw, i never sa 1522b, only 1520b. Do you really have 22 ?

pshipkov wrote on 2024-05-19, 05:20:

@MikeSG
What was the point of the flexible ribbon mod ?

I'm simplifying the flush circuit on my design using the Improve Tech circuit. Just missing a few connections.

Will share the gerber files after testing.

Post is at Re: Custom interposer module for TI486SXL2-66 PGA168 to PGA132 - HELP!

pshipkov wrote on 2024-05-20, 06:18:

That is unfortunate indeed. Lets see if 4036yb handles it better for you. Not surprised that aha-1522b did better than 1542c#. O […]
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That is unfortunate indeed. Lets see if 4036yb handles it better for you.
Not surprised that aha-1522b did better than 1542c#.
Once you get the Advansys / SIIG controller, it should move the needle quite a bit.

Btw, i never sa 1522b, only 1520b. Do you really have 22 ?

Yes, i actually have the AHA-1522B, which just means it contains the integrated floppy port and related IC's. This saves an ISA slot, assuming you use floppy. If you need a multi-I/O card anyway, then it wouldn't help much.

Edit: Attached photo of the 1522B on testbed:

@MikeSG
I guess you are doing this in the name of completeness, correct ?
I tested these SXL2 CPUs on a LOT of motherboards and with one exception they worked just fine. Not sure if additional improvements are actually needed.
If i don't solder the two chips on the adapter will it still function ?
My point is that simplicity is a positive factor for DIY hobby contraptions given the limited time we can allocate to this stuff.

@Feipoa
Good point that most 386 mobos require multi-i/o card, so 1522 does not bring a lot of value over 1520.

pshipkov wrote on 2024-05-21, 05:59:

I guess you are doing this in the name of completeness, correct ? I tested these SXL2 CPUs on a LOT of motherboards and with one […]
Show full quote

I guess you are doing this in the name of completeness, correct ?
I tested these SXL2 CPUs on a LOT of motherboards and with one exception they worked just fine. Not sure if additional improvements are actually needed.
If i don't solder the two chips on the adapter will it still function ?
My point is that simplicity is a positive factor for DIY hobby contraptions given the limited time we can allocate to this stuff.

I had the same thinking in this regard. I hope Mike makes the invalidation circuit disable-able with a jumper, or minimally a solder bridge. I haven't run into any 386 boards which didn't work with the SXL2 out of the box with the cyrix.exe utility. Do you recall the exact motherboard you tested which didn't work with the SXL2 and cyrix.exe.

Nonetheless, I think there could be some obscure OEM or MCA systems out there that may benefit from this external cache invalidation circuit, whereby MEMW# and/or cyrix.exe won't cut it. There was another user in this thread who had an MCA system and needed to add an inverter and OR gate to the design to get the SXL2 working, however this option was already added to Alpha 1.

Or maybe with the Improve-It invalidation scheme, we can bypass cyrix.exe all together, or get improved AHA-1542 support? And hopefully without sacrificing overclock-ability. I know I tested for this in the past with a similar Improve-It interposer, but no longer recall the outcome.

pshipkov wrote on 2024-05-21, 05:59:

@Feipoa
Good point that most 386 mobos require multi-i/o card, so 1522 does not bring a lot of value over 1520.

However, for all my systems, I use PS/2 for the mouse, thus skipping the multi-I/O card entirely. You can probably see why the 1522B and 1542CP w/bulit-in floppy appealed to me. If there's ISA slots left, I may still add a serial I/O card to test serial mice if needed.

pshipkov wrote on 2024-05-21, 05:59:

@MikeSG I guess you are doing this in the name of completeness, correct ? I tested these SXL2 CPUs on a LOT of motherboards and […]
Show full quote

@MikeSG
I guess you are doing this in the name of completeness, correct ?
I tested these SXL2 CPUs on a LOT of motherboards and with one exception they worked just fine. Not sure if additional improvements are actually needed.
If i don't solder the two chips on the adapter will it still function ?
My point is that simplicity is a positive factor for DIY hobby contraptions given the limited time we can allocate to this stuff.

It's mostly for completeness. It's a "wire free" cache invalidation in case the Cyrix utility doesn't work, but I guess it works 99.9% of cases anyway.

I'll just delete the extra chips.

The extra cache invalidation circuit may also be useful if the user is wanting to run a non DOS-based operating system which cannot run the cyrix.exe utility, like Windows NT, OS/2, or CP/M. I'm not sure if CP/M and OS/2 can run cyrix.exe)

BTW other OSes can be usually booted from plain DOS via GRUB4DOS, so you can configure your HW with DOS utils, call GRUB4DOS.EXE and chainload other OS like NT. It can be all automated in autoexec.bat and grub menu.lst to select some boot item within a given timeout.

RayeR wrote on 2024-05-21, 20:11:

BTW other OSes can be usually booted from plain DOS via GRUB4DOS, so you can configure your HW with DOS utils, call GRUB4DOS.EXE and chainload other OS like NT. It can be all automated in autoexec.bat and grub menu.lst to select some boot item within a given timeout.

This is what I do, but not everyone wants to put in this extra effort.

Updated my post containing PCB design req, Bill of Materials with the new simpler layout. Re: Custom interposer module for TI486SXL2-66 PGA168 to PGA132 - HELP!

Ordered them today and will arrive between Jun 20 - 30 to test. Once it works I'll upload the gerber files.

Only doubts are whether the press-fit holes are within tolerance. There was an option when ordering to ensure +/- 0.05mm but was +$280AUD.