Questions tagged [motorola-68000]

for questions about the Motorola 68000 microprocessor

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15
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3answers
1k views

How did the original Apple Macintosh and Atari ST use protected mode?

The Macintosh, ST, and Amiga were all 68000 CPU systems released in 1984-85, along with their respective new Operating Systems. While this was 5 years before protected mode became commonplace on Intel ...
17
votes
5answers
2k views

Can a retro-computer be a useful way to learn computer-architecture fundamentals?

I've been reading about the fundamentals of computer architecture, but I think I could get a better grasp of the basics if I could could have an actual device to play with. I had considered building ...
14
votes
3answers
2k views

Replacing 80286 with 68000

Suppose you wanted to take a 286 PC and replace the CPU with a 68000, not at the initial design stage, but actually modifying the finished machine, on the theory that they both have 24 bits of address ...
6
votes
1answer
363 views

How to integrate an 512kB EEPROM on a A3660 accelerator board at $00F00000?

I am currently experimenting with Chucky's re-engineered A3660 accelerator board for the Commodore Amiga (3000(T) and 4000(T)). My ultimate goal is to add an additional 512kB EEPROM to the ...
22
votes
5answers
2k views

Why is the Amiga ROM at a high memory location, and RAM in low memory?

When a 68000 CPU powers up, it reads a few words at memory location zero to get the initial stack pointer and program counter. That suggests to me that a computer system designer would put the system ...
5
votes
1answer
382 views

What was Burst Mode on the 68030 and why didn't the A2630 support it?

Inspired by this question, I'm curious what burst mode was on the 68030 and why wasn't it supported on the A2630 accelerator card commonly found in the Amiga 2500/30? I had one of these machines and ...