24 May 2022, 03:40 | #1 |
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Amiga 1000 pseudo fast ram
Hi everyone,
Sorry if this was already asked before, but I just thought of that when ready about the fact that Amiga 1000 read kickstart directly from floppy into a special "write once RAM". With that in mind, my question is: Would it be technically possible to code game which would install itself as a "kickstart" in 256KB, and then that game would be running off that special locked ram which is (probably?) running as fast as fast ram? This would leave the default 256KB of real chip ram completely free. Of course this would make such technique only compatible with the amiga 1000; But still I wondered if it was ever done? |
24 May 2022, 03:48 | #2 |
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It has been done, but not often. I have a vague recollection of reading about Dragon's Lair being one of the few games that did this, but I'm not certain.
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24 May 2022, 09:06 | #3 |
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I’ve not really spent much time looking at the Write once RAM daughter board on my A1000, but I do know that the RAM chips on there are DRAMs… if the board doesn’t have any hardware to refresh those chips (it might have), then it will need to use Agnus to refresh them and the ram access speed would be no faster than SlowRAM.
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24 May 2022, 18:02 | #4 |
Natteravn
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It would be the same speed as the Kickstart "ROM", once loaded into the A1000's WOM. But is it really slower than the A500's ROM? Never heard that before...
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24 May 2022, 18:22 | #5 |
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It should have real fast ram speeds. It has no connections to Agnus chip ram side bus/signals and 74LS393 (2x4 bit binary counter) probably is used as a refresh counter.
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24 May 2022, 20:12 | #6 |
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Should be easy enough to measure, right? Maybe there's some extra fun emulation issues with the refreshes
Is it possible to get a >7MHz accelerator board with fast ram for the A1000? In that case wouldn't it have to limit access speed to the "ROM" to whatever the RAM chips support? |
26 May 2022, 01:09 | #7 | |
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Quote:
That would seem like a clever hackish way to have lower RAM requirements on the 1000 compared to other Amigas. |
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26 May 2022, 02:26 | #8 |
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Dragon's Lair is the only game that I know of that utilized the 256k WCS. Yes after a reset you had to reload Kickstart.
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27 May 2022, 23:32 | #9 |
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Yep, as I remember Dragon's Lair required 1M RAM unless you had an Amiga 1000, then 512k would work because it used the WOM..
That was nice.. ;-) |
28 May 2022, 01:17 | #10 |
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IIRC Toni showed a trick (that he had found?) that opened up the WOM for writing again. I wish I had it saved to file...
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28 May 2022, 04:03 | #11 |
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28 May 2022, 07:32 | #12 | |
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Quote:
Also see DumpA1000BootROM on Aminet. |
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02 June 2022, 18:23 | #13 | |
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Quote:
Code:
DoReset lea ResetCode(pc),a5 movea.l _AbsExecBase,a6 jsr _LVOSupervisor(a6) CNOP 0,4 ResetCode lea.l $fc0002,a0 nop reset jmp (a0) |
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