a500 rev 5 1mb chipmem mod... confused - Page 6

Jope · 14 September 2018, 08:42

It's the same thing as _EXRAM. If this signal is grounded, then GARY asserts _RAMEN to the Agnus when accessing $C00000 memory, making your trapdoor memory show up as Slow RAM.

Removing the _EXRAM/_EXTICK connection is the same thing as toggling the switch on a trapdoor RAM expansion. The board does not get mapped to $C00000 any more.

If you do a 1MB Chip modification, you do not want the same RAM to be visible on both memory ranges.

With the signal disabled, the RAM is still on the bus, but the Agnus just considers it as additional Chip RAM as long as you also adjust JP2.

Starglider 2 · 14 September 2018, 08:43

Thanks!

brufnus · 16 August 2023, 19:32

A couple of weeks ago I finally purchased a std. A500 in addition to my CDTV.

Many many years ago, being a novice, I bought an Amitech Maximem 512 KB trapdoor expansion card, unbeknownst that it doesn't fit in the CDTV (doh)... so I've had that in my possesion ever since.
A couple of years ago I also bought a TF534 for the CDTV, but had no luck making it work - it works flawlessly in the "new" Amiga, though. I then went on purchasing an IDE2CF converter including WB3.1 on a 4 GB card - boots perfectly from that one.

Yesterday, in the middle of the night, I decided to try my luck with the 1 MB chipmem mod; after some meddling with it, removing the switch from the trapdoor board and an initial green screen and guru alerts, I made it work properly. It's a rev 6, by the way.

So now I'm among the ranks of those fortune enough to have at least 1 MB graphics mem on the 500. Wheeeyyyy! :-D

P.S. The CDTV got a Pistorm instead, shortly after I'd given up on the TF, giving me tremendous speed, USB/SD/wifi/RTG and oceans of memory on that one. c",)

utri007 · 17 August 2023, 23:22

@jope

I recently made a 1mb chip ram mods to Rev6a anf 5 mobos. I had trouble to find guides with picture. I found tons of eab threads, but with missing picture.

Could this be solved with a sticky thread in hardware mods??

Jope · 18 August 2023, 09:33

Hmm, maybe we could make a sticky thread about it.

Did you find suitable pictures to share? Guessing the best way here would be to have them as attachments.

I found this old magazine scan with google, it's already attached to some thread here. https://eab.abime.net/attachment.php...6&d=1177615199 I don't know how to find the thread in question though.

16 August 2023, 19:32	#103
brufnus Registered User Join Date: Jul 2021 Location: Aarslev, Denmark Posts: 90	A couple of weeks ago I finally purchased a std. A500 in addition to my CDTV. Many many years ago, being a novice, I bought an Amitech Maximem 512 KB trapdoor expansion card, unbeknownst that it doesn't fit in the CDTV (doh)... so I've had that in my possesion ever since. A couple of years ago I also bought a TF534 for the CDTV, but had no luck making it work - it works flawlessly in the "new" Amiga, though. I then went on purchasing an IDE2CF converter including WB3.1 on a 4 GB card - boots perfectly from that one. Yesterday, in the middle of the night, I decided to try my luck with the 1 MB chipmem mod; after some meddling with it, removing the switch from the trapdoor board and an initial green screen and guru alerts, I made it work properly. It's a rev 6, by the way. So now I'm among the ranks of those fortune enough to have at least 1 MB graphics mem on the 500. Wheeeyyyy! :-D P.S. The CDTV got a Pistorm instead, shortly after I'd given up on the TF, giving me tremendous speed, USB/SD/wifi/RTG and oceans of memory on that one. c",) Last edited by brufnus; 16 August 2023 at 19:46. Reason: addition

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14 September 2018, 08:42	#101
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,863	It's the same thing as _EXRAM. If this signal is grounded, then GARY asserts _RAMEN to the Agnus when accessing $C00000 memory, making your trapdoor memory show up as Slow RAM. Removing the _EXRAM/_EXTICK connection is the same thing as toggling the switch on a trapdoor RAM expansion. The board does not get mapped to $C00000 any more. If you do a 1MB Chip modification, you do not want the same RAM to be visible on both memory ranges. With the signal disabled, the RAM is still on the bus, but the Agnus just considers it as additional Chip RAM as long as you also adjust JP2.

14 September 2018, 08:43	#102
Starglider 2 Registered User Join Date: Jan 2014 Location: California Posts: 1,146	Thanks!

17 August 2023, 23:22	#104
utri007 mä vaan Join Date: Nov 2001 Location: Finland Posts: 1,655	@jope I recently made a 1mb chip ram mods to Rev6a anf 5 mobos. I had trouble to find guides with picture. I found tons of eab threads, but with missing picture. Could this be solved with a sticky thread in hardware mods??

18 August 2023, 09:33	#105
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,863	Hmm, maybe we could make a sticky thread about it. Did you find suitable pictures to share? Guessing the best way here would be to have them as attachments. I found this old magazine scan with google, it's already attached to some thread here. https://eab.abime.net/attachment.php...6&d=1177615199 I don't know how to find the thread in question though.

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