Hopefully last slightly off-topic: My PAL research work which evolved out of this thread is now finalized and published at https://github.com/jonnyh64/palrvs.
@Chuck(G) , thanks for the clarification. In the meanwhile, I found https://nsa40.casimages.com/img/2021/03/25/210325010228265393.png, which dates back to 2007. I‘ll take this as earliest reference for the idea and will not dig any further.
As I plan to set up a GitHub page with information about PAL16L8 reversing together with my Python scripts, I want to make sure to credit everybody appropriately, as the core ideas are surely not my merit.
@Chuck(G), are your forum posts from Oct 2011 the first appearance of the brute force...
Rodney, thanks for testing my jed files!!
The "EPROM dump" was binary different, and I found the reason: The DIR_245 equation generated by pete.py was wrong.
pete.py:
!DIR_245 =
AEN_2 & AIOW & !XBHE
# MEMW & RAS & !AEN_1
# AEN_2 & !MEMW & !XBHE;
Equation found by you:
!DIR_245 =...
I'm finishing my PAL reversing work which evolved out of this thread and would like to summarize a little...
With the help of Eudimorphodon (thanks!!) and after studying PAL and GAL datasheets, I was able to write my own simplified GAL assembler which can convert the pete.py generated equations...
Rodney, many thanks for explaining all the ISA bus details - quite a while until I found enough time to thoroughly read through it.
I was really concerned that this RAM connection choice reduces RAM performance, but it really doesn‘t seem warranted.
Is SAx/SDx then directly connected to Ax/Dx...
Ok, after reading Eudimorphodon‘s post again, I understood that the clock on the ISA bus could be switched between full CPU speed and, e.g., 8 MHz. Sounds scary to me, but I‘m more or less a novice for such stuff. I still would think that a proprietary RAM expansion connector would simplify the...
Hi Rodney,
I read through the last couple of posts, but I'm still a little puzzled.
Looking at the 80286 pinout, it seems to me it has a very "classic" design: address bus, data bus, a few control lines and exactly one clock (named CLK). Connecting SRAM to it somehow seems obvious with...