A500 Rev5 1Mb Chip Ram Mod

gurth · 23 February 2014, 21:07

Could someone point m towards a tutorial to modify my Rev5 A500 to 1Mb Chip Ram please?

I have dropped in a 8752A Agnus and already have a 512k trap door expansion in place.

(Google'in at the mo but keep fend Rev6a).

Thanks in advance.

zipper · 23 February 2014, 21:21

At least Megachip manual has the instructions in it:
http://amiga-manuals.xiik.net/manual...Manual_ENG.rar

gurth · 23 February 2014, 21:24

Perfect thank you very much.

gurth · 23 February 2014, 22:57

Worked a treat. 1Mb Chip Ram!

zipper · 24 February 2014, 11:43

Nice! (did it to my rev6a, then Megachipped to 2 MB).

Zetr0 · 24 February 2014, 12:06

Quote:

Originally Posted by zipper

Nice! (did it to my rev6a, then Megachipped to 2 MB).

Sweet! *pics please*

=)

zipper · 24 February 2014, 13:14

It's buried under the KS swither in my a500T, sorry...

Jope · 26 February 2014, 20:52

Just to have the relevant info in this thread..

JP2 goes like in the Rev6 and for JP7, just flip the switch in your 3rd party ram expansion to disable it. If your ram expansion has no switch, then you must find the _EXRAM trace that goes from the trapdoor slot to GARY's pin 32 and cut it. Alternately you can just lift out GARY and bend out pin32 so that it no longer makes contact with the socket to isolate the signal. (no, don't bend out GARY's pin)

gurth · 26 February 2014, 22:00

With my 8752A Agnus in place am I stuck in NTSCv bit hard to tell with my scart connection and plasma screen (42" Kickstart 1.3 boot screen!)

Jope · 27 February 2014, 06:23

That can be alleviated by gluing a thin sliver of sticky tape on the pal/ntsc select pin before plugging the new agnus into the Rev5 A500.

16 February 2018, 09:38

Sorry for posting to an old thread, but some relevant info regarding chip RAM mods. It's also possible to add 1 MB chip RAM with no motherboard modifications whatsoever, if you are afraid you'll ruin your Amiga or have rev 3 motherboard where this mod is more difficult. Check out https://inkoovintagecomputing.wordpr...modifications/

This does require electronics skills though, but may be worth for some users. Also, it's possible to switch between chip/slow RAM and PAL/NTSC with some jumpers after this.

ajk · 16 February 2018, 11:13

That is a very interesting approach. A middle ground between a regular RAM expansion and the MegAChip. If only the PLCC connectors were not so expensive

utri007 · 07 July 2023, 12:06

I tried to found how to make 1mb chip ram mod to rev 5. motherboard, but all pictures seems to disappeared.

I'm little confused, when / what situation I need to cut JP7A?

Also, I have problems to make these mods work with KS1.3 but not with 3.1. Is this normal, should Agnus 8372 just work with lower kickstarts?

zipper · 07 July 2023, 13:46

MegAChip manual has the instructions: http://amiga.resource.cx/manual/MegAChip.pdf

23 February 2014, 21:07	#1
gurth Registered User Join Date: Dec 2013 Location: Halifax Posts: 225	A500 Rev5 1Mb Chip Ram Mod Could someone point m towards a tutorial to modify my Rev5 A500 to 1Mb Chip Ram please? I have dropped in a 8752A Agnus and already have a 512k trap door expansion in place. (Google'in at the mo but keep fend Rev6a). Thanks in advance.

26 February 2014, 20:52	#8
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,864	Just to have the relevant info in this thread.. JP2 goes like in the Rev6 and for JP7, just flip the switch in your 3rd party ram expansion to disable it. If your ram expansion has no switch, then you must find the _EXRAM trace that goes from the trapdoor slot to GARY's pin 32 and cut it. Alternately you can just lift out GARY and bend out pin32 so that it no longer makes contact with the socket to isolate the signal. (no, don't bend out GARY's pin) Last edited by Jope; 10 October 2015 at 08:51.

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23 February 2014, 21:21	#2
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,838	At least Megachip manual has the instructions in it: http://amiga-manuals.xiik.net/manual...Manual_ENG.rar

23 February 2014, 21:24	#3
gurth Registered User Join Date: Dec 2013 Location: Halifax Posts: 225	Perfect thank you very much.

23 February 2014, 22:57	#4
gurth Registered User Join Date: Dec 2013 Location: Halifax Posts: 225	Worked a treat. 1Mb Chip Ram!

24 February 2014, 11:43	#5
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,838	Nice! (did it to my rev6a, then Megachipped to 2 MB).

24 February 2014, 13:14	#7
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,838	It's buried under the KS swither in my a500T, sorry...

26 February 2014, 22:00	#9
gurth Registered User Join Date: Dec 2013 Location: Halifax Posts: 225	With my 8752A Agnus in place am I stuck in NTSCv bit hard to tell with my scart connection and plasma screen (42" Kickstart 1.3 boot screen!)

27 February 2014, 06:23	#10
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,864	That can be alleviated by gluing a thin sliver of sticky tape on the pal/ntsc select pin before plugging the new agnus into the Rev5 A500.

16 February 2018, 09:38	#11
invincing Posts: n/a	Sorry for posting to an old thread, but some relevant info regarding chip RAM mods. It's also possible to add 1 MB chip RAM with no motherboard modifications whatsoever, if you are afraid you'll ruin your Amiga or have rev 3 motherboard where this mod is more difficult. Check out https://inkoovintagecomputing.wordpr...modifications/ This does require electronics skills though, but may be worth for some users. Also, it's possible to switch between chip/slow RAM and PAL/NTSC with some jumpers after this.

16 February 2018, 11:13	#12
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	That is a very interesting approach. A middle ground between a regular RAM expansion and the MegAChip. If only the PLCC connectors were not so expensive

07 July 2023, 12:06	#13
utri007 mä vaan Join Date: Nov 2001 Location: Finland Posts: 1,655	I tried to found how to make 1mb chip ram mod to rev 5. motherboard, but all pictures seems to disappeared. I'm little confused, when / what situation I need to cut JP7A? Also, I have problems to make these mods work with KS1.3 but not with 3.1. Is this normal, should Agnus 8372 just work with lower kickstarts?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

07 July 2023, 13:46	#14
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,838	MegAChip manual has the instructions: http://amiga.resource.cx/manual/MegAChip.pdf