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Dave Tweed
Dave Tweed
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The book 68000 Hardware Manual will show you how to build a basic DRAM interface for "oldschool" DRAM, which you should be able to find dirt cheap and fast enough that you have 0 wait states.

On the other hand, US$25 might be well worth the design convenience of just using SRAM—and it looks to me like, given you don't need very fast SRAM to keep up with a 68000, that you could probably find more than 4MB for quite a bit cheaper. (Even if you need to use a latch or something to interface a slow CPU with very fast modern SRAM.)

Oh, and if you can find one, try to use a 68010 instead of a 68000. It's electrically compatible but the supervisor mode has a couple bug fixes for bus error recovery, so it can implement virtualization.

EDIT: Some of the links on the page linked above are now broken. This is an alternate link to the same document: http://bitsavers.informatik.uni-stuttgart.de/pdf/peripheralTechnology/68000%20Hardware%20Manual.pdf

The book 68000 Hardware Manual will show you how to build a basic DRAM interface for "oldschool" DRAM, which you should be able to find dirt cheap and fast enough that you have 0 wait states.

On the other hand, US$25 might be well worth the design convenience of just using SRAM—and it looks to me like, given you don't need very fast SRAM to keep up with a 68000, that you could probably find more than 4MB for quite a bit cheaper. (Even if you need to use a latch or something to interface a slow CPU with very fast modern SRAM.)

Oh, and if you can find one, try to use a 68010 instead of a 68000. It's electrically compatible but the supervisor mode has a couple bug fixes for bus error recovery, so it can implement virtualization.

The book 68000 Hardware Manual will show you how to build a basic DRAM interface for "oldschool" DRAM, which you should be able to find dirt cheap and fast enough that you have 0 wait states.

On the other hand, US$25 might be well worth the design convenience of just using SRAM—and it looks to me like, given you don't need very fast SRAM to keep up with a 68000, that you could probably find more than 4MB for quite a bit cheaper. (Even if you need to use a latch or something to interface a slow CPU with very fast modern SRAM.)

Oh, and if you can find one, try to use a 68010 instead of a 68000. It's electrically compatible but the supervisor mode has a couple bug fixes for bus error recovery, so it can implement virtualization.

EDIT: Some of the links on the page linked above are now broken. This is an alternate link to the same document: http://bitsavers.informatik.uni-stuttgart.de/pdf/peripheralTechnology/68000%20Hardware%20Manual.pdf

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Chris Hanson
Chris Hanson
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The book 68000 Hardware Manual will show you how to build a basic DRAM interface for "oldschool" DRAM, which you should be able to find dirt cheap and fast enough that you have 0 wait states.

On the other hand, US$25 might be well worth the design convenience of just using SRAM—and it looks to me like, given you don't need very fast SRAM to keep up with a 68000, that you could probably find more than 4MB for quite a bit cheaper. (Even if you need to use a latch or something to interface a slow CPU with very fast modern SRAM.)

Oh, and if you can find one, try to use a 68010 instead of a 68000. It's electrically compatible but the supervisor mode has a couple bug fixes for bus error recovery, so it can implement virtualization.