09 November 2018, 11:17 | #1 |
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A500 1MB Chip Ram
So I was surprised to discover that my new-to-me A500 has 1MB of chip ram (using the trap-door expansion). From what I've read this was something that came in with the A500 Plus and could be added to late revision A500 boards with a modification. I had thought my unit was much older as I have a red power LED and the serial number is fairly low. . . perhaps the board has been replaced at some point, I'm not sure. I forgot to make a note of the PCB revision when I opened it up last.
Anyway. . .what does 1MB chip ram do for me on an otherwise OCS machine? Is there any software that I can run that I otherwise couldn't? So far all I've noticed is that some early software gets upset about it. I tried to run the old Red Sector Demo Maker which thinks I don't have enough memory, but used to run on my old 0.5 chip / 0.5 slow machine. Interestingly it made the same complaint on a 1200 with 2mb chip ram so I'm guessing it may be looking for fast ram specifically, somehow. |
09 November 2018, 12:27 | #2 |
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Join Date: Jul 2003
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Almost any A500 can be upgraded to 1MB of Chip RAM by swapping the Agnus and reconfiguring a few jumpers.
The rev5 is moderately easy to do and the rev6 is the easiest. Usually people make these switchable so that you can revert to the 512/512 configuration for those old pieces of software, that expect it. So yes, some old programs specifically only understand Fast RAM at the $c00000 address, where the trapdoor normally puts it. |
09 November 2018, 12:30 | #3 |
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Is there any benefit to 1MB chip ram? So far it only seems to be causing problems.
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09 November 2018, 12:43 | #4 |
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Benefit: more screens open at the same time, larger music modules possible in protracker.. Basically you can do more with audio/gfx.
If you mainly care about playing games, 512/512 is usually plenty, there are not very many that require 1MB of Chip. |
09 November 2018, 14:08 | #5 | |
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Quote:
Ah, yes, Rise of the Robots - pretty, but sh*tty :> |
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09 November 2018, 14:25 | #6 |
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The two largest (or only the largest?) maps of Turbo RAKETTI 1 also requires 1MB of Chip. :-)
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09 November 2018, 14:29 | #7 |
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Thanks guys. I think I may investigate if the mod can be easily undone. My 1200 should cover the special cases...
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09 November 2018, 15:31 | #8 |
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It all depends on your motherboard revision.. Perhaps check that first.
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09 November 2018, 19:25 | #9 |
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Revision 6A. I believe it was Professor Plum in the Billiard Room with the craft knife and big blob of solder on JP2.
Edit: Undid these two mods, showing 0.5 chip and 0.5 slow in all the right places And RSI Demo Maker works. Last edited by WildW; 09 November 2018 at 19:59. Reason: Updated |
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