I think that's me pretty much finished with the CPLD coding. I had to make a minor tweak to the switching logic to get some of the PALPROMs working correctly. This is what I initially had:
and this is what I changed it to to get it working correctly:
I thought both would have done the same thing, but that wasn't the case!
With that change, I have been able to emulate 13 different PALPROMs on my IntegraB board. The only slight niggle I have is that I run out of space if I try to implement the final PALPROM type without removing one of the other types. Basically, I can build the code to run MEGA3 / SpellMaster (Computer Concept 128K PALPROMs), or I can build the code to run Wapping editor (Watford Electronics 64K PALPROM), but I can't add both types, with a toggle to switch between them.
The Mega3 / SpellMaster switching logic is at lines 713..729
The Watford Electronics switching logic is at lines 694..711 (currently commented out)
The combined switching logic is at lines 731..756 (currently commented out)
An alternative combined switching logic is at lines 758..787 (currently commented out)
Can anyone see any further optimisation opportunities, that would allow me to build the code using the combined switching logic? Unfortunately, I can't move the I/O around. That ship sailed a long time ago. I have to stick with the current pin assignments.
Note that the code is very sensitive to some very small changes. For example, remove the '|| !bbc_nRST' check from the above 'wire pp4Clk' line, and I run out of space again! But sometimes I can make a relatively big change, and it will still fit. This makes it very difficult to know what the right answer should be!
Thanks!
For those who are interested, these are the PALPROM types (and actual PALPROMs) that are currently supported:
Bank 9 (Type: Computer Concepts 32K): Inter-Word, Master ROM, AMX Design2
Bank 10 (Type: Computer Concepts 64k): Inter-Base, Publisher, Wordwise Plus II
Bank 10 (Type: Watford Electronics 32K V1): QuestPaint, ConQuest, PCB Designer
Bank 10 (Type: Watford Electronics 32K V2): TED
Bank 11 (Type: Computer Concepts 128K): SpellMaster, Mega3
Bank 11 (Type: Watford Electronics 64K): Wapping Editor
With this arrangement, you can have upto 3 PALPROMs installed at any one time. These can also be switched out for normal RAM, or ROM. You have to use jumpers to switch in the different Bank 10 PALPROM types, and currently you have to reprogram the CPLD to switch between the different Bank 11 PALPROM types.
Code:
wire pp4Clk = (!nRDS && GenBankSel[10]) || !bbc_nRST;always @(posedge pp4Clk) beginCode:
wire pp4Clk = !((!nRDS && GenBankSel[10]) || !bbc_nRST);always @(negedge pp4Clk) beginWith that change, I have been able to emulate 13 different PALPROMs on my IntegraB board. The only slight niggle I have is that I run out of space if I try to implement the final PALPROM type without removing one of the other types. Basically, I can build the code to run MEGA3 / SpellMaster (Computer Concept 128K PALPROMs), or I can build the code to run Wapping editor (Watford Electronics 64K PALPROM), but I can't add both types, with a toggle to switch between them.
The Mega3 / SpellMaster switching logic is at lines 713..729
The Watford Electronics switching logic is at lines 694..711 (currently commented out)
The combined switching logic is at lines 731..756 (currently commented out)
An alternative combined switching logic is at lines 758..787 (currently commented out)
Can anyone see any further optimisation opportunities, that would allow me to build the code using the combined switching logic? Unfortunately, I can't move the I/O around. That ship sailed a long time ago. I have to stick with the current pin assignments.
Note that the code is very sensitive to some very small changes. For example, remove the '|| !bbc_nRST' check from the above 'wire pp4Clk' line, and I run out of space again! But sometimes I can make a relatively big change, and it will still fit. This makes it very difficult to know what the right answer should be!
Thanks!
For those who are interested, these are the PALPROM types (and actual PALPROMs) that are currently supported:
Bank 9 (Type: Computer Concepts 32K): Inter-Word, Master ROM, AMX Design2
Bank 10 (Type: Computer Concepts 64k): Inter-Base, Publisher, Wordwise Plus II
Bank 10 (Type: Watford Electronics 32K V1): QuestPaint, ConQuest, PCB Designer
Bank 10 (Type: Watford Electronics 32K V2): TED
Bank 11 (Type: Computer Concepts 128K): SpellMaster, Mega3
Bank 11 (Type: Watford Electronics 64K): Wapping Editor
With this arrangement, you can have upto 3 PALPROMs installed at any one time. These can also be switched out for normal RAM, or ROM. You have to use jumpers to switch in the different Bank 10 PALPROM types, and currently you have to reprogram the CPLD to switch between the different Bank 11 PALPROM types.
Statistics: Posted by KenLowe — Sat Aug 10, 2024 4:57 pm