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Old 29 November 2011, 06:38   #1
platatomi
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A500 Revision 4 motherboard, ROM upgrade?

I am looking to upgrade the 1.3 ROM in my A500 to 3.1 but ebay only has chips for rev3+5 and 6a. My board is revision 4, will these work? If not, what are my options?

Why can i find ABSOLUTELY NO info about rev 4 motherboards online?

Also, my board has a sticker that says "W.C. Build March 1987 NTSC 1076" What does this mean?
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Old 29 November 2011, 08:12   #2
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dunno about the problem with that revision, but in many A500 I needed to add the missing resistor pack for KS3.1 to work, check out the sticky thread about it.
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Old 29 November 2011, 09:18   #3
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Lots of detailed pictures of this rev4 please, both inside and out. :-)

You won't find info about it, because it is very rare. Maybe it was never mass produced?

The 3.1 rom probably needs the same treatment as the rev5 board.
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Old 29 November 2011, 09:34   #4
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I will post pictures tomorrow. Here are some other details:

serial number: CA100000049

The chip socket labels like CPU, ROM, PAULA, etc. are absent.

Some chips are in different places, the ROM chip is shifted higher (looking at board from front to back) so top of ROM is even with top of 68000.

The revision number and model identifier are in a different place, under the floppy drive instead of below it.


Thats what I remember of the top of my head. Pictures coming in about 8-12 hours.
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Old 29 November 2011, 23:01   #5
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Sorry for pic delay

I planned to upload tyhe pics earlier today but was having trouble as the files are extremly large, (7MB !) needed to go to school now so I will post the pics in about 5 or 6 hours after this post. Thanks for waiting.
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Old 30 November 2011, 04:18   #6
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pictures here!

Here are the first few pics.

Attachment 29962

Attachment 29964

Attachment 29963
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Old 30 November 2011, 04:36   #7
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Finally pics here!

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I have more pics but can only attach 8?
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Old 30 November 2011, 06:45   #8
platatomi
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Some pics of RCA connectors and LEDs

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Old 30 November 2011, 06:59   #9
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Thanks for the pics, very interesting.

Seems indeed that it's been made between the R3 and R5. It has the NMB keyboard that is associated with R3 boards but has the sticker C= logo that all rev5s had.

I'm pretty sure I won't ever see another one with this revision. :-D
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Old 30 November 2011, 07:36   #10
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(a lot of questions, I am new to the Amiga platform)

So nobody knows anything about these rev 4 boards?
Even how many were made?
Could we conduct some kind of questionnaire on Amiga fan sites like this to gather info?
Is there any danger of motherboard damage using a KS ROM of rev 5?
Also, how much could one of these rev 4 boards be worth?
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Old 30 November 2011, 08:50   #11
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Quote:
Originally Posted by platatomi View Post
(a lot of questions, I am new to the Amiga platform)

So nobody knows anything about these rev 4 boards?
Perhaps if you could track down some of the people whose nicknames are etched onto the circuit board. :-)

Quote:
Even how many were made?
That data is almost impossible to come by even for the more well known revisions.

Quote:
Could we conduct some kind of questionnaire on Amiga fan sites like this to gather info?
We could. However I'm pretty sure you're on your own with your Rev4 board.. Before you arrived, I'm willing to bet none of us hobbyists still active in the community knew about its existence.

Another rare board is Rev7, which only gets a few mentions anywhere. I don't own one myself, I got the pictures from a friend on the internet.
http://jope.fi/amiga/index.php?sfpg=...ODRjMTAzZDFhYQ

Quote:
Is there any danger of motherboard damage using a KS ROM of rev 5?
I don't see any danger.

Just remember:
Quote:
Originally Posted by VillageTronic
For Rev 3 and Rev 5 boards, the ROM socket must have pin 1 connected to pin 31 and the ROM IC must have connected pin 21 to bent-up pin 31.
Quote:
Originally Posted by platatomi View Post
Also, how much could one of these rev 4 boards be worth?
Whatever someone is willing to bid on ebay to be honest.

I value any A500 at $10 maximum, but that's just me.

I'm sure you could get more if you crafted an ebay description that matter-of-factly states what the board is, without resorting to the usual L@@K RARE!!! blasting that ebay sellers do for things that are not rare in reality.. Then a few strategically placed mentions on the various Amiga boards about your new ebay auction and then you just wait.

If you intend to cash in with it, forget the 3.1 upgrade, it has to be kept original. :-) Or if you do the upgrade, do the socket modification (connect pin 1 to 31) to an additional socket that you just press in to the one on the motherboard.

Last edited by Jope; 30 November 2011 at 09:00.
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Old 30 November 2011, 08:59   #12
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Ok. Sounds like it is best left as-is and tucked away. Glad I ran into you in the forums, it sounds like your one of the very few who knows anything about this board.

Thanks for your input.
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