22 September 2021, 11:37 | #21 |
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What is 'game crawling'? Frame rate issues?
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22 September 2021, 12:37 | #22 | |
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In developers defence, they probably thought of an Amiga A500 the same as a Spectrum or C64, I.e. no significant revisions, and when sales start to fall off, Commodore will simply develop and release a new machine that likely has no connection to the A500 at all, so programmers didn't necessarily worry about owners of big box Amigas with processor cards, because they would represent such a tiny minority of people that bought games, their target was to ensure rhe A500 was well catered for, as that is the biggest volume machine. |
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22 September 2021, 13:00 | #23 |
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All books I have read said that the instruction set was the same disregarding the 680x0 CPU (meaning that 68010 -> 68060 use the same base as the 68000)
But here I understand that a 68000 instruction can have a different meaning on a 68020. Is that correct? |
22 September 2021, 13:10 | #24 | |
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When an Amiga crashes, it will put important details on the stack, and does them in a specific format when 68000 is the cpu. You can also put stuff on the stack and pull stuff off the stack (like parameters etc, return addresses). However, the stack format of 68020 is slightly different, and this is where Chuck Rock failed, the code only assumed 68000, in which case moving stuff onto the stack would have been predictable, on 68020 the difference in the stack frame format means that the predicted result was no longer valid, and so it crashed. I think someone was over complicating a quite easy job, that was understood how to do easily and without problems. Lots of programmers didnt mess around with stacks in such a direct way, they would push and pull register contents to the stack and not do anything else with it, which means their code will work no matter the stack frame format. |
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22 September 2021, 13:13 | #25 |
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It sounds like that even if you program directly against the hardware on an Amiga, you can still go too low-level
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22 September 2021, 13:37 | #26 |
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Thanks for the precisions Galahad
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22 September 2021, 19:16 | #27 | |
CaptainM68K-SPS France
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Quote:
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22 September 2021, 23:59 | #28 |
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23 September 2021, 01:28 | #29 |
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23 September 2021, 01:57 | #30 |
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23 September 2021, 04:45 | #31 |
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But surely at this time the publishers must of being complaints or games returned from the big boxed amiga owners?
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23 September 2021, 08:27 | #32 |
CaptainM68K-SPS France
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23 September 2021, 09:11 | #33 |
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23 September 2021, 09:57 | #34 |
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23 September 2021, 12:19 | #35 |
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23 September 2021, 14:05 | #36 | |
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Strategy type games or flight sims that installed on a hard drive yes, platformers....not so much. |
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23 September 2021, 14:57 | #37 |
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from the start they had published a list that games that didn't work. People knew.
(then we whdload-fixed all of them ) |
23 September 2021, 18:46 | #38 |
CaptainM68K-SPS France
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23 September 2021, 19:04 | #39 |
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23 September 2021, 19:32 | #40 |
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Yes, some Amiga games was assembled using DevPac (Atari ST version). For checking if this is Atari ST exe file you must/can check not only $601A at begining of file, but also relocs table at the end of exe file, are very easy to recognise.
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