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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: utri007 on October 06, 2021, 06:15:29 PM
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Hello,
here is rare rev7 Amiga 500 motherboard. It is manufactured 1988, when there was still rev 5 and rev 6 motherboards on sale.
Rev 6 was sole for something like 1990, so does anyone know why rev 7 is from 1988 and was it pulled back?
https://1drv.ms/u/s!AsdbQ2CKZfHPhLh5y82Gk2w3_Zp8aA
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I can only guess at the possible reasons why:
1. There were problems with rev 7 so they stopped making them and rolled back to an older version. I’m sure that chip tower near the trap door added costs that Commodore didn’t want to have to pay…
2. Only certain factories were producing rev 7 while most of the others stayed on older revs.
3. Given how Commodore’s various international marketing divisions had to place orders with HQ, maybe most countries didn’t want rev 7 machines. (Just like how no divisions ordered the finished A2200.) Maybe they didn’t want to have to provide post-sale support/service for another variant.
As to the strange matter of rev 7 being older than expected, another possibility that I wonder about is that rev 6 was an internal version that was never released, like the rev 5 A2000. The next version was 7, they pulled that one from distribution, then created rev 6A, a fork from rev 6 instead of fixing/iterating rev 7.
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6a & 7 share the same schematics....
https://archive.org/details/system-schematics-a-500-revisions-5-6a-7/page/12/mode/2up
So I'm not sure what the difference actually is...
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6a & 7 share the same schematics....
https://archive.org/details/system-schematics-a-500-revisions-5-6a-7/page/12/mode/2up
So I'm not sure what the difference actually is...
Judging by the part number (314981-02), that seems to be a revised version of the schematics. I wonder if 314981-01 would more clearly delineate differences between 6A and 7. i.e., the differences were so minor they didn't even bother to describe them in the revised printing.
A tiny circuit pathway layout change? Something not significant enough to require a different schematic.
Could rev 7 have been pre-jumpered to use 1MB Chip instead of 512K Chip / 512K Slow? I could imagine Commodore trying something like that and then pulling back.
@ utri007
Are you the original owner of the machine with this board? What country did you buy it in?
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I'm not a original owner, but 1mb chip mod is made by me. Case and mobo s# doesn't match.
This is NTSC machine and I have not idee how it ended up to here Finland.
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Could rev 7 have been pre-jumpered to use 1MB Chip instead of 512K Chip / 512K Slow? I could imagine Commodore trying something like that and then pulling back.
It kinda reminds of the time they assigned an agnus chip the wrong number for the pin out they used.
It's commodore, they might have had an argument over what to call it and sent the wrong artwork.
The other option is slightly different for some part commodore thought they could get cheaper, then didn't.
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Here better pictures.
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IF I remember correctly, back in the day some games would not run from floppy if there was no chip mem, 1 Meg fast did not cut it.
Chris
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With no chipram, the amiga won’t even start.
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And if there was no fast, you had a slide show on many games or lots of disk swaps