8087 on 8088 motherboard that have no socket for it

[Jan de Lange]

The initial flatcable based design is not running very stable because of the signal length.

Ah yes. Understood. And we don't need a flat cable, just a different orientation.

 

[Jan de Lange]

I will do some scaling to see if if fits.

 

[LambdaMikel]

The initial flatcable based design is not running very stable because of the signal length.

it runs stable with 7.1 Mhz but not with much more

 

[1ST1]

The flatcable needs a lot of effort to shield it. The PCB-Only-Version is much better. But maybe it would make sense to redesign again like I proposed in the classic computing forum, that idea without the 90 degrees turn of the new sockets is a lot more space saving.



Side view. https://forum.classic-computing.de/forum/index.php?thread/34973-8088-8087-co-processor-modul-für-rechner-ohne-8087-sockel/&postID=524706#post524706

 

[LambdaMikel]

The flatcable needs a lot of effort to shield it. The PCB-Only-Version is much better. But maybe it would make sense to redesign again like I proposed in the classic computing forum, that idea without the 90 degrees turn of the new sockets is a lot more space saving.

View attachment 1297819

Side view. https://forum.classic-computing.de/forum/index.php?thread/34973-8088-8087-co-processor-modul-für-rechner-ohne-8087-sockel/&postID=524706#post524706

Yeah, I would have done that, but this doesn't fit in the Euro PC...

 

[LambdaMikel]

Here is an updated version - a user reported that he needed to add additional bodge wires for thicker power rails and decoupling caps to increase stability for it to run at 9.54 Mhz. I didn't have this issue with my 2 installations in 2 different EuroPCs, but I also have a very decent after-market external PSU (maybe less ripples?)
Attached is a new version.
https://github.com/lambdamikel/europc-copro

 

[GloriousCow]

This is great, thank you. Was looking to do something similar to let me plug my 8087-socket-sniffer into my Tandy 1000...