15 July 2008, 01:22 | #1 |
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Blizz 030 Mk4 - How to enable the MMU
I ran Sysinfo last night and noticed that the MMU was not 'enabled'. Do you have to do something in the start sequence to enable it or something?
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15 July 2008, 03:02 | #2 |
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strange... what are the markings on the cpu? what OS do you use? if you boot with a 3.0/3.1 floppy disk and run sysinfo, does it still say the MMU is not enabled?
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15 July 2008, 03:35 | #3 | |
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Quote:
I'm pretty sure it's 'MC68030RC50C' which I think is the latest variant. Didn't all 030's have an MMU anyway? Last edited by NovaCoder; 15 July 2008 at 05:13. |
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15 July 2008, 04:31 | #4 |
I hate potatos and shirts
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All non-EC 030 have MMU.
Try to use this command: CPU databurst datacache fastROM. Don't do this in 3.9! Only in 3.0/3.1!!! |
15 July 2008, 05:15 | #5 |
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15 July 2008, 05:53 | #6 |
I hate potatos and shirts
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Boot with a plain 3.1 disk and type the command...
Then start sysinfo again. |
15 July 2008, 06:00 | #7 |
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SysInfo only shows the MMU as enabled if something is using it. No need to try to enable it, it's either there and working or not. (Try running something like Enforcer if you really must see it working.)
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15 July 2008, 06:52 | #8 |
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That's interesting, so the OS doesn't use it for it's own memory management. Ok, I'll try Enforcer and see what happens. I'm sure it works fine, I was just surprised to see that it wasn't being used.
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15 July 2008, 07:14 | #9 |
I hate potatos and shirts
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MMU is not for memory management! Is intended for relocating portions of it using the MMU as a "pointer".
Example: when you copy the ROM into RAM and then "tricks" the OS and programs to look in a specific address instead the original. Another use is for controlling a "virtual memory". Never used in any Amiga OS (but some patches/programs exist). |
15 July 2008, 08:34 | #10 |
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The official blurb.
A memory management unit (MMU), sometimes called paged memory management unit (PMMU), is a computer hardware component responsible for handling accesses to memory requested by the central processing unit (CPU). Its functions include translation of virtual addresses to physical addresses (i.e., virtual memory management), memory protection, cache control, bus arbitration, and, in simpler computer architectures (especially 8-bit systems), bank switching. Motorola 68030 Memory management unit Thanks for all the info peoples |
17 April 2016, 14:37 | #11 | |
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Quote:
Where I get this LawBreaker from? I also want to enable MMU but in 68030 to see it is not fake made from 68EC030. Someone may say use WhichAmiga for that and yes I already did, but it has a known long time bug: "always report 68EC030 if 68030mmu is not in use." So I need some reliable tool to check if MMU exists and then enable it for WhichAmiga and SysInfo. |
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17 April 2016, 16:11 | #12 |
Amigan
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Not entirely true. It is used for example to mark Chip-RAM as non-cacheable as the Blitter can change data in chip ram without the CPU knowing.
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17 April 2016, 16:20 | #13 |
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It comes with enforcer archive.
But note that it is practically impossible to reliably detect if 68EC030 has bad or working MMU. At least some 68EC030's are 68030's with MMU that didn't pass all tests. Some MMU operations may fail, some MMU operations may hang the system instantly and so on.. (For example I had 68EC030 that worked perfectly fine with enforcer but instantly hung if more complex MMU software was used) Only 68040+ non-MMU/FPU models can be detected reliably. |
17 April 2016, 19:30 | #14 | |
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Quote:
But it's also in the Enforcer lha package. |
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17 April 2016, 22:18 | #15 |
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I don't think this is true, because that would cause problems for cpus that have cache and no mmu.. afaik, chipram is marked non-cacheable by asserting some hardware signals directly on the cpu package.
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18 April 2016, 00:57 | #16 | |
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Quote:
I tried rkauer's advice and OS3.1 CPU command. Also noticed that just "CPU fastrom" enables MMU and "CPU nofastrom" disables it. After enabling it WhichAmiga shows CPU as MC68030 and MMU enabled. I assume same goes with Sysinfo. I wonder if this unreliability is also why WhichAmiga or Sysinfo is not showing mask revisions for 030, like it shows for 060 (and possibly 040 too, cannot remember). |
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18 April 2016, 12:08 | #17 | |
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Quote:
68060 (and only 68060) supports PCR register that returns model type (full/EC/LC) and mask revision. |
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19 April 2016, 09:14 | #18 |
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I've read somewhere (but i don't remember where) the following procedure to detect an MC68EC030.
First initialize the MMU to map one page of memory onto another page as if the part was an MC68030. If the MMU instructions cause an illegal instruction, then the part is an MC68EC030. If the MMU instructions do not cause an illegal instruction, then write a flag to the mapped page. Disable the MMU and read the location with the flag. If the flag's physical address matched the logical address, the part is an MC68EC030. If the flag's physical address does not match the logical address, then the part is an MC68030. Is this procedure reliable or does it fail on some 68EC030 ? AFAIK mask revisions are impossible to get by software on 030 ; there is simply no way to do that. I've got both RC50B and RC50C ; they behave exactly the same. |
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