16 October 2020, 23:04 | #21 | |
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Quote:
"I can answer the last part of your question: yes, the Mac II could use a 68851. For a time, Virginia Tech required incoming Computer Science freshmen to purchase a (heavily discounted) Mac II running A/UX, Apple's first in-house-developed UNIX. These machines shipped with 2MB RAM, an 80MB HD (huge for the time), and a 68851 pre-installed; A/UX required the 68851 to work." https://retrocomputing.stackexchange...mu-replacement |
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16 October 2020, 23:09 | #22 |
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@Don Adan
Read the last part of my post again....I was talking about the MC68841 (and not the 68851). I think the 68841 may have been used on workstations, but not home computers AFAIK as the 68010 didn't feature prominently on 68K home computers. I'm aware of the Mac-II and 68851 as I used Macs a lot in the late 80s and early/mid-90s at university. |
17 October 2020, 00:16 | #23 | |
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Quote:
http://www.generationamiga.com/2016/...ered-by-amiga/ |
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17 October 2020, 10:32 | #24 |
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17 October 2020, 11:16 | #25 |
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Re-read earlier replies. Lots of programs "support" 68851 = use it like 68030 without TTRs. No Amiga program (please, prove me wrong!) use 68851 features that are not in 68030 MMU. No Amiga program even uses all 68030 MMU features like page table limits.
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17 October 2020, 12:15 | #26 | |
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Quote:
Concerning the instruction, this is "test if breakpoint flag in PSR is clear, set register d1 if so". The PMMU had additional breakpoint support, but this was not very useful as you had to inject a special instruction into the code, and one could use the standard MC68K "illegal" instruction as well (as most debuggers do), with just a tiny little bit of extra services provided by the PMMU. Unclear why anyone would want that or need it. As a question to the OP, where is this instruction sequence taken from? |
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