I guess you write a reply "You must not clock a 20 MHz PIC at 32MHz".
I can tell you upfront that is not the issue with the project. Cycle is only 8 MHz anyway.
And it works 100% no problems.
I am currently making a new prototype for a 68000 computer.
I have done away with all the things I did not like.
For instance wire junctions are plain evil.
Only using 8bit memory chip. The new design will latch the upper 8 bit, and it is only using 5 lower address bits directly, a shifting register for the rest.
8K memory as for now!
If I want a superfast system, there is no need to use a 68000. Far too much power consumption as well.
I want to get some 68000 code actually executing no matter how.
Made the PIC working today, added two serial displays.
It was...
Everything that can go wrong went wrong. From wire shorts, to swapped wires, and too high clock frequency. I had to insert delays everywhere, to resolder the serial wires, to measure each for shorts.
It works now! And I wrote the defines for all the port bits to interface the 68000 in the morning.
Only PORT C is left blank, basically.
16F946 has large FLASH memory, 0x3FFF address space. About 0x0500 words are used up by the serial display code.
Have to solder quite a few wires, and write code to test the RAM, that's the next step.
Hope the old chip is still OK. Have others here if not.
Including 68SEC000 + support chips + CPLD board. Somehow it has to be this old 5V technology.
I want to see if it can work with less than 5V. Many experiments to do!
Also wrote some definitions for the 68000 vectors, have to load some things into the RAM before starting.
Don't tell me to use a GAL or CPLD or EPROMs and stuff like that. I have all these things here. I do not want to use it. I have hundreds of 74xx chips here, even made some proto circuits in the past for 68000. All way too many wires and a big mess to remember how it works.
I can tell you upfront that is not the issue with the project. Cycle is only 8 MHz anyway.
And it works 100% no problems.
I am currently making a new prototype for a 68000 computer.
I have done away with all the things I did not like.
For instance wire junctions are plain evil.
Only using 8bit memory chip. The new design will latch the upper 8 bit, and it is only using 5 lower address bits directly, a shifting register for the rest.
8K memory as for now!
If I want a superfast system, there is no need to use a 68000. Far too much power consumption as well.
I want to get some 68000 code actually executing no matter how.
Made the PIC working today, added two serial displays.
It was...
Everything that can go wrong went wrong. From wire shorts, to swapped wires, and too high clock frequency. I had to insert delays everywhere, to resolder the serial wires, to measure each for shorts.
It works now! And I wrote the defines for all the port bits to interface the 68000 in the morning.
Only PORT C is left blank, basically.
16F946 has large FLASH memory, 0x3FFF address space. About 0x0500 words are used up by the serial display code.
Have to solder quite a few wires, and write code to test the RAM, that's the next step.
Hope the old chip is still OK. Have others here if not.
Including 68SEC000 + support chips + CPLD board. Somehow it has to be this old 5V technology.
I want to see if it can work with less than 5V. Many experiments to do!
Also wrote some definitions for the 68000 vectors, have to load some things into the RAM before starting.
Don't tell me to use a GAL or CPLD or EPROMs and stuff like that. I have all these things here. I do not want to use it. I have hundreds of 74xx chips here, even made some proto circuits in the past for 68000. All way too many wires and a big mess to remember how it works.
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