Good news, the complete MCS-51 support is done! No hardware mod required. Works as-is on the iAPX-86 UCAS.
I did some tests on a lot of different HMOS/CMOS chips, from the 80s to modern ones : 8031, 8032, 8044, 8051, 8052, and up to 80C521. Newer implementations (like the DS80C320 “clock-tripled”) also works fine. After some tuning, I was able to run that MCU at 40 Mhz !
Here are some pics :
AMD 80C521 ES – Tested at 12 MHz
Intel P87C51 Q7805 ES – Tested at 24 MHz
Maxim/Dallas DS80C320-MCL+ – Tested at 40 MHz
Maxim/Dallas DS80C320-MCL+ / Decent clock signal at 40 MHz
Intel TN80C32 – Tested at 12 MHz / Also fine with PLCC Socket !
Last but not least, here is a video I just recorded :
The speed difference at same clock frequency between old & new MCS-51 is amazing !