Upgrading an A500 to an A500+ tech questions

Merlin · 26 April 2007, 17:20

Hi

Before anyone asks, I have found and downloaded Syko's document regarding this subject, however I have a couple of questions that the document doesn't answer. I have a basket case A500+ board which was damaged by a leaking battery, however the RAM and custom chips are OK.

1. Will an 8375 Agnus go straight into the socket where the 8372 is on the A500 with no modifications, i.e. isolating pins as per magazine article?

2. Can I desolder the RAM chips from the A500+ and fill the remaining four positions on the A500, will the new added RAM chips be recognised, especially if I replace the Agnus chip as per 1 above, and will it be chip or fast RAM?

3. I am going to change the Denise chip, is there any point in changing the Paula or Gary chips as well?

4. Are there any other modifications required to reconfigure the modified A500 as an A500+?

5. If I change the Kickstart chip to the 2.04 version, is there any point keeping the 1.3 Kickstart and using a ROM switcher, I am thinking of the cheap "piggyback" mod as found on Aminet?

Merlin

Anubis · 26 April 2007, 18:31

5. There were some old games that I couldn't play on my A500+ back in the days. So if you need this computer for 1.x games as well, then yes, it makes sense to make kickstart switcher.

For the rest - I had no idea that such a thing is possible. (making A500 into A500+) Shouldn't purchase of A500+ require less work??

zipper · 26 April 2007, 21:14

500 to 500+ no problem; done it with Super Denise, Megachip2 and KS 2.05, then 3.1. That's it

Jope · 26 April 2007, 21:15

1. please give info on that magazine article, the 2MB part is not pin compatible
2. yes, it will be chip or fast depending on jp2 and jp7 positions.
3. paula and gary were not upgraded
4. the normal a500 can't have 2MB chip unless you build a 2MB agnus adapter and add the other 1MB to that.

Merlin · 26 April 2007, 21:32

@ Jope

I've attached the magazine article, the text jumps around a bit on the pages and is difficult to follow in places.

The article mentions the 8372A and 8372B being interchangeable but doesn't talk much about the 8375 Agnus compatibility - where can I get a comparison of the pinouts of the different versions to check the compatibility?

I am looking to upgrade the A500 to 1Mb on the main motherboard with the RAM chips from the A500+, the 500 had four chips whereas the 500+ has eight on the main board, if I add four that will make a 1Mb machine won't it? I have an 0.5Mb A501 to put into the trapdoor to end up with 1.5Mb in total if my plan works, is this possible?

@ zipper, can you talk me through what you did on your machine?

You guys need to realise that I do this stuff for the challenge, I am not called Merlin for nothing, my soldering iron is a magic wand in my hands, I just don't want to wreck a working A500 by trying the impossible or by putting the wrong Agnus chip in the socket.

I have the chips, so why not?

Merlin

Jope · 26 April 2007, 22:13

Get a hold of the A500 rev6 and A500+ schematics (download), the pinouts are available there.

If you want to have 1MB on the motherboard and an additional 512 ranger fast in the trapdoor, you will need to make an address decoder circuit for the trapdoor ram. By default it will overlap the four empty sockets on the A500 rev6 motherboard.

zipper · 27 April 2007, 06:54

Quote:

Originally Posted by Merlin

@ zipper, can you talk me through what you did on your machine?

Mainly what's described here, the mobo fix to add trapdoor memory to Chip area and then replacing (1 MB) Agnus with this:

http://amiga.resource.cx/manual/MegAChip.pdf

alexh · 27 April 2007, 08:42

You cannot change an A500 into an A500+ without extra hardware (A MiniMega chip) but you can go full ECS by adding a 1Mbyte Agnus, making changes to the motherboard for 1Mbyte Chip-RAM and upgrading the denise.

But why bother when you can get an A600 for £10

Merlin · 27 April 2007, 09:29

@ Alexh

I know, I just have the hacking bug and like to tinker with projects like this, it keeps my mind active and it's definitely old skool stuff.

Merlin

Jope · 27 April 2007, 09:53

Please make your homebrew 2MB chip adapter plans public once the project is finished.

alexh · 27 April 2007, 11:30

It would be very easy to do that... but the sockets cost a fortune.

darksun9210 · 27 April 2007, 12:55

I tried to upgrade my rev5 A500 with a super denise, and 3.1rom.
i couldn't get anything out of it but then putting the 1.3rom back in, i got a guru with "software error". put the original denise back in, all working again.
had a duff 3.1rom which didn't help the situation. got a good 3.1rom now, and still problems with the Super Denise. waiting till i can find a minimegachip 2Mb chipram upgrade, as i guess this is the missing link.

i can find NTSC ones, but i can't find PAL megachips for love nor money.

i read somewhere that if you ground pin 41 on the agnus, it defaults to NTSC, but if it left not connected, it defaults to PAL... can anyone confirm this? as it may be a way to convert NTSC megachips to PAL?

alexh · 28 April 2007, 00:15

You can get PAL 2Mbyte 8375 Agnuii from broken A500+'s (battery damage).

It's the MiniMegi PCB's which are the rarity.

I can confirm that 8375 Agnus is NOT dual PAL/NTSC and what you are describing is the older 1Mbyte Agnus.

I still feel you are MAD to try and upgrade an A500 you can get an A500+/A600 for £10.

A2000 / CDTV this is an acceptable upgrade because there is no alternative.

jimbo100 · 28 April 2007, 06:05

Quote:

Originally Posted by alexh

I still feel you are MAD to try and upgrade an A500 you can get an A500+/A600 for £10.

Where can I get a A600 for £10?

alexh · 28 April 2007, 10:04

That is their usual selling price here in the UK.

http://cgi.ebay.co.uk/Commodore-Amig...QQcmdZViewItem

http://cgi.ebay.co.uk/AMIGA-600_W0QQ...QQcmdZViewItem

http://cgi.ebay.co.uk/Amiga-600_W0QQ...QQcmdZViewItem

http://cgi.ebay.co.uk/Commodore-Amig...QQcmdZViewItem

http://cgi.ebay.co.uk/COMMODORE-AMIG...QQcmdZViewItem

amigarobbo · 28 April 2007, 23:02

I got one for 10.52, £10 on postage. then spent over £20 on a 1 meg Memory increase, and a bit more than that on a 512 Meg flash Hard drive!

Dread to think how much a accelerator would cost!

10-20 times the price of a A600? All a bit silly really.. But fun!

jimbo100 · 29 April 2007, 08:37

Quote:

Originally Posted by alexh

That is their usual selling price here in the UK.

http://cgi.ebay.co.uk/Commodore-Amig...QQcmdZViewItem

http://cgi.ebay.co.uk/AMIGA-600_W0QQ...QQcmdZViewItem

http://cgi.ebay.co.uk/Amiga-600_W0QQ...QQcmdZViewItem

http://cgi.ebay.co.uk/Commodore-Amig...QQcmdZViewItem

http://cgi.ebay.co.uk/COMMODORE-AMIG...QQcmdZViewItem

Shame only one woudl ship to Australia and wanted 50 pounds, PASS!

alexh · 29 April 2007, 09:20

Get me a work Visa for Oz and I'll ship you 10x of them

jimbo100 · 29 April 2007, 13:09

Quote:

Originally Posted by alexh

Get me a work Visa for Oz and I'll ship you 10x of them

Granted!

alexh · 29 April 2007, 13:23

Get it me in writing and I'll be there... A600's in my suitcase.

26 April 2007, 17:20	#1
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	Upgrading an A500 to an A500+ tech questions Hi Before anyone asks, I have found and downloaded Syko's document regarding this subject, however I have a couple of questions that the document doesn't answer. I have a basket case A500+ board which was damaged by a leaking battery, however the RAM and custom chips are OK. 1. Will an 8375 Agnus go straight into the socket where the 8372 is on the A500 with no modifications, i.e. isolating pins as per magazine article? 2. Can I desolder the RAM chips from the A500+ and fill the remaining four positions on the A500, will the new added RAM chips be recognised, especially if I replace the Agnus chip as per 1 above, and will it be chip or fast RAM? 3. I am going to change the Denise chip, is there any point in changing the Paula or Gary chips as well? 4. Are there any other modifications required to reconfigure the modified A500 as an A500+? 5. If I change the Kickstart chip to the 2.04 version, is there any point keeping the 1.3 Kickstart and using a ROM switcher, I am thinking of the cheap "piggyback" mod as found on Aminet? Merlin

27 April 2007, 12:55	#12
darksun9210 Because i can. Join Date: Apr 2007 Location: London Age: 45 Posts: 25	Super Denise needs the upgraded Agnus to work...? I tried to upgrade my rev5 A500 with a super denise, and 3.1rom. i couldn't get anything out of it but then putting the 1.3rom back in, i got a guru with "software error". put the original denise back in, all working again. had a duff 3.1rom which didn't help the situation. got a good 3.1rom now, and still problems with the Super Denise. waiting till i can find a minimegachip 2Mb chipram upgrade, as i guess this is the missing link. i can find NTSC ones, but i can't find PAL megachips for love nor money. i read somewhere that if you ground pin 41 on the agnus, it defaults to NTSC, but if it left not connected, it defaults to PAL... can anyone confirm this? as it may be a way to convert NTSC megachips to PAL?

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26 April 2007, 18:31	#2
Anubis Retro Gamer Join Date: Jan 2005 Location: Underworld Age: 51 Posts: 4,063	5. There were some old games that I couldn't play on my A500+ back in the days. So if you need this computer for 1.x games as well, then yes, it makes sense to make kickstart switcher. For the rest - I had no idea that such a thing is possible. (making A500 into A500+) Shouldn't purchase of A500+ require less work??

26 April 2007, 21:14	#3
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,839	500 to 500+ no problem; done it with Super Denise, Megachip2 and KS 2.05, then 3.1. That's it

26 April 2007, 21:15	#4
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,869	1. please give info on that magazine article, the 2MB part is not pin compatible 2. yes, it will be chip or fast depending on jp2 and jp7 positions. 3. paula and gary were not upgraded 4. the normal a500 can't have 2MB chip unless you build a 2MB agnus adapter and add the other 1MB to that.

26 April 2007, 22:13	#6
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,869	Get a hold of the A500 rev6 and A500+ schematics (download), the pinouts are available there. If you want to have 1MB on the motherboard and an additional 512 ranger fast in the trapdoor, you will need to make an address decoder circuit for the trapdoor ram. By default it will overlap the four empty sockets on the A500 rev6 motherboard.

27 April 2007, 08:42	#8
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,379	You cannot change an A500 into an A500+ without extra hardware (A MiniMega chip) but you can go full ECS by adding a 1Mbyte Agnus, making changes to the motherboard for 1Mbyte Chip-RAM and upgrading the denise. But why bother when you can get an A600 for £10

27 April 2007, 09:29	#9
Merlin AmiBay MegaMod Join Date: Mar 2007 Location: Manchester, UK Age: 62 Posts: 1,163	@ Alexh I know, I just have the hacking bug and like to tinker with projects like this, it keeps my mind active and it's definitely old skool stuff. Merlin

27 April 2007, 09:53	#10
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,869	Please make your homebrew 2MB chip adapter plans public once the project is finished.

27 April 2007, 11:30	#11
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,379	It would be very easy to do that... but the sockets cost a fortune.

28 April 2007, 00:15	#13
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,379	You can get PAL 2Mbyte 8375 Agnuii from broken A500+'s (battery damage). It's the MiniMegi PCB's which are the rarity. I can confirm that 8375 Agnus is NOT dual PAL/NTSC and what you are describing is the older 1Mbyte Agnus. I still feel you are MAD to try and upgrade an A500 you can get an A500+/A600 for £10. A2000 / CDTV this is an acceptable upgrade because there is no alternative.

28 April 2007, 10:04	#15
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,379	That is their usual selling price here in the UK. http://cgi.ebay.co.uk/Commodore-Amig...QQcmdZViewItem http://cgi.ebay.co.uk/AMIGA-600_W0QQ...QQcmdZViewItem http://cgi.ebay.co.uk/Amiga-600_W0QQ...QQcmdZViewItem http://cgi.ebay.co.uk/Commodore-Amig...QQcmdZViewItem http://cgi.ebay.co.uk/COMMODORE-AMIG...QQcmdZViewItem

28 April 2007, 23:02	#16
amigarobbo Registered User Join Date: Mar 2007 Location: UK Posts: 181	I got one for 10.52, £10 on postage. then spent over £20 on a 1 meg Memory increase, and a bit more than that on a 512 Meg flash Hard drive! Dread to think how much a accelerator would cost! 10-20 times the price of a A600? All a bit silly really.. But fun!

29 April 2007, 09:20	#18
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,379	Get me a work Visa for Oz and I'll ship you 10x of them

29 April 2007, 13:23	#20
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,379	Get it me in writing and I'll be there... A600's in my suitcase.

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