10 July 2021, 11:42 | #1 |
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Use MMU for creating fake slow-fast memory
Hi like the title says, would it be possible to remap 0x00c00000 to fast memory using the mmu? The new aca1234 by icomp has this memory as selling point and I was wondering if with an mmu we can achieve the same thing on a blizzard 1230. If possible would be amazing to integrate it in a custom 1.3 kickstart, maybe with a blizkick module, that when booting it will automatically make this memory available.
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10 July 2021, 12:31 | #2 |
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Sure it should be possible but I don't see the point. Which app needs 0xC00000 in fastmem?
only games can do this, and in that case, use whdload which remaps this slow mem to real fast when possible (sometimes it can fail to use real 32 bit mem because of wrong programming, but that is really a rare case) |
10 July 2021, 12:37 | #3 | |
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10 July 2021, 14:32 | #4 |
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10 July 2021, 14:35 | #5 |
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This is my code from ~25 years ago written for myself (probably not even BlizKick existed yet).
I haven't checked the code and it's probably rough and doesn't have any kind of refinement, but it sure worked because I remember running disks that only went on KS1.3/A500_512chip+512fake@$c00000 on my Blizzard 1230. Take it as it is, I don't know if I want to make a more functional or complete version EDIT: I hadn't seen Thomas's message yet. His is certainly a better and generalized solution, therefore absolutely recommended. Last edited by ross; 10 July 2021 at 14:44. |
11 July 2021, 10:40 | #6 | |
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Thanks to you both |
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11 July 2021, 14:19 | #7 | |
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Yes, you need the NDK, but the source can be easily modified so as not to require it (a few EQUs are enough). However it would be interesting to make a slightly more complete version of it to also support KS1.2, a toggle for enabling icache, support for NTSC and 1MB of chip-ram.. I don't really know how useful an application of this kind actually would be, I think about it and see if I feel like it |
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11 July 2021, 14:59 | #8 | |
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11 July 2021, 15:35 | #9 | |
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My code softkick by itself, but of course it could be modified to use the blizzard maprom function. The MMU table is very optimized for the 030 (er.., it only works with it..) and is created to handle 24bit memory in 512KB chunk as you like. The ATC is so tiny that fully fit in the MMU cache and the performance impact is negligible. The asm-one error at line 43 is probably due to the crplabel that the assembler simply confuses with the register, change it to something different at both line 43 and line 61 (crp-> crpm) |
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11 July 2021, 15:45 | #10 | |
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11 July 2021, 16:02 | #11 |
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11 July 2021, 18:46 | #12 |
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crp/drp/srp is fine, you have to change pmove.d to pmove.q if you are using asm-one&family.
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11 July 2021, 19:48 | #13 | |
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vasmand it also accepts .q But it also works without specifying any size, like pmovesolo or whatever you want (.b, .w, .l, .d, .q ..) It's probably the right choice because crpis 64-bit anyway |
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