07 February 2021, 02:42 | #1 |
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List of A500 mobo revisions and appropriate chips?
Just gave a rev 6A A500 a new PicoPSU. <3
All my A500s were bought from others except two that I've kept since back in the day, and this is not one of those two. One is in the infirmary awaiting diagnosis. Therefore, is there a handy list where everyone can check which chips (including Kickstart) "belong" on which revision motherboard? Some A500 models had A500+ chips, I know. Still, if there's some official list (assuming previous owner, or C-Amiga didn't pull some tricks when it was at its peak)? Just so that everything is proper and good. |
08 February 2021, 09:12 | #2 |
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I don't think there is a general list.
Here's a rough guide: Rev 3: OCS Denise, OCS Agnus, often Toshiba Gary but the last ones might have a CSG Gary, Kick 1.2, power LED goes off Rev 5: OCS Denise, OCS Agnus, CSG Gary, Kick 1.2 and 1.3, power LED goes off Rev 6: OCS Denise, 1MB Agnus, CSG Gary, Kick 1.3, power LED goes dim Rev 8: ECS Denise, 2MB Agnus, CSG Gary, Kick 1.3 or 2.04, power LED goes dim |
08 February 2021, 17:15 | #3 |
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The Rev 5 will work okay if you give it a 1MB Agnus?
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08 February 2021, 18:21 | #4 |
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08 February 2021, 20:31 | #5 | |
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Yes.
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Hey BTW o/ Maybe formalize. (Below is not about the Rev 6 mobo in title, but it would be neat with a list.)
I'm asking provokingly to get answers, I know. And still only official products from factory. |
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08 February 2021, 21:48 | #6 |
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They did castrated rev 8 boards as A500 - demand was there but no A500 boards anymore.
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08 February 2021, 21:56 | #7 | |
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Actually Kick 2.0 is less of a point than the handling of slowmem. Let's make it both then. A500s with Kick 2.0 and slowmem gets mounted as chipmem in hardware. Else we need castration details |
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08 February 2021, 22:31 | #8 | |
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There is also a Rev7 (I have one of them) but I am not sure what the differences are and they are quite rare. I got this one from the UK though, so it was sold there at least. |
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08 February 2021, 22:52 | #9 |
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Yeah, sorry for mentioning rare boards that are hard to find. Rev7 may have been a transition A500+ motherboard also, depending on components. What does yours have on it?
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08 February 2021, 23:16 | #10 | |
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I'm not sure which Agnus got fitted though, but probably a 2MB capable one (8375?). |
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09 February 2021, 07:22 | #11 |
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I've got two A500 systems with a rev8 board, and I would agree with the above. They match the specs of a regular A500, not A500+. I'm guessing Commodore had spent up all the earlier motherboards, but there was still commercial demand for the plain A500.
However, I haven't had these from new at all, they are later purchases. I could check exact chip revisions if it is of interest, but it won't be 100% reliable. |
09 February 2021, 08:56 | #12 |
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The rev8 is only compatible with the 2MB Agnus, so that's what the rev8 A500s (non plus) got. :-) Mine came with a super denise (the seals were intact when I got it). The board is configured for 512k chip on the motherboard and 512k slow in the trapdoor and kickstart 1.3. RTC unpopulated on the motherboard. The badge on the case is like the wide A500 plus badge, but only says A500 on it. Green power LED.
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11 February 2021, 01:19 | #13 |
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I guess it was a short lived rev, from 6A to 8. It is not a machine I have in use, so I will need to digg it out of my storage area to check.
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11 February 2021, 09:00 | #14 |
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Here's pictures I was sent by someone. Perhaps 4play? http://jope.fi/amiga/a500rev7/
Looks like a 512k Agnus was fitted, and there is no RTC, so this implies that it is closer to a rev 6 than rev 8. |
12 February 2021, 02:04 | #15 | |
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My Rev 6A's has 512K chip + slowmem, 8372 Agnus, and white 1MB chip RAM mask symbols on the motherboard, like in the pictures. I'm filled with questions now I've also been away from Amiga for a spell, so sorry if they're newb questions. - Wasn't there a kick 2.0 A500 then? Rev7 pictures seem to show a kick 1.3. (Wikipedia says no. I guess we must have bought them as an upgrade and swapped them.) - Can you have 1MB chip + trapdoor RAM on any A500? (I guess not, since it requires 8372 and this will always map extra RAM as chipmem?) - ... But the "always" is just not true, since my Rev 6A's have 8372 and keeps slowmem as slowmem. - Can an 8371 Agnus be retrofitted to an unmodded Rev 6A board without conflict with the other chips or incompatible with some software? (The Rev7 seems to have done so?) - Did Rev8 have RTC then, and was it the only A500 revision to have it? Last edited by Photon; 12 February 2021 at 02:13. |
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12 February 2021, 06:25 | #16 |
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The rev 8 boards in A500 systems don't have the RTC components (and therefore fortunately also no battery) installed. These are of course easily added to the board if needed.
I've got some photos in an old thread of mine where you can see all the RTC related stuff completely untouched. |
12 February 2021, 07:41 | #17 | |||||
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For the downgraded rev8 A-500, one TTL chip is also missing and some jumpers are in a different order for it to be a 512 mobo/512 trapdoor setup. The jumpers can be adjusted, the missing RAM chips and the TTL chip added for it to become an A500+ with 1MB on the mobo and 1MB possible in the trapdoor. Instructions are pretty easy to find here on support.hardware. Last edited by Jope; 12 February 2021 at 07:51. |
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12 February 2021, 13:23 | #18 |
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Where in the memory space the trapdoor expansion ends up is configured by motherboard jumpers - it isn't affected by agnus revision (but you still need a 8372a for 1MB chip, of course).
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12 February 2021, 13:24 | #19 | |||||
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I have an A500 with accelerator and two stock(?) ones. The warranty seal having been broken on both is the whole background for my questions. I just want a good grip again on exactly what was manufactured and sold. That way, I can first make sure it's stock and then figure out what I can change. (re: 8372) Quote:
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Hmm, one more curious question Since I have this and get 1MB Chip, how is ECS Denise not required? It already can read from addresses in the 512k-1MB chip range, or all addressing is done by Agnus so that no other ECS chips are required (e.g. Paula)? |
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12 February 2021, 13:34 | #20 | ||
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So not HW, but SW compatibility reasons. Quote:
Super Denise's reason to exist is that it supports higher horizontal frequencies than 15kHz. So if you're happy with PAL/NTSC (everyone running ECS should accept this fate), a regular Denise can be used even with a 2MB Agnus just fine. |
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