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/  Forum Index
   /  Classic Amiga Hardware
      /  Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
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Tpod 
Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
Posted on 18-Apr-2024 20:03:40
#1 ]
Regular Member
Joined: 16-Oct-2009
Posts: 150
From: UK

So I'm planning on upgrading my spare Rev 5 A500 Motherboard to 1Mb Chip RAM (I know how & have the 8372A Agnus).

I was wondering if after upgrading I could still use it with my Zydec MEGABOARD (has a pass through connector & also a 'GARY Board')?

See: https://bigbookofamigahardware.com/ - it's penultimate on the RAM Expansions List.

On an OCS A500 the MEGABOARD has 1Mb RAM but if you plug in an additional standard 512Kb upgrade you have a total of 1.5Mb SlowRAM (Ranger Memory) along with the Amigas 512Kb Chip RAM.

I'm not certain what would happen RAM wise (hopefully end up with 1Mb Chip & 1Mb Slow) with the MEGABOARD & on the electrical front I don't want to just try it & hope for the best!

---------------------------------------------

Just to add, it seems very unlikely that using the Megaboard after the Rev 5 board mod would cause any actual damage, but I'm not 100% sure hence the question.

Last edited by Tpod on 19-Apr-2024 at 11:05 AM.
Last edited by Tpod on 19-Apr-2024 at 11:03 AM.

_________________
A1200+Mediator+Voodoo3+040+130mbRAM+0S3.9
A2000+Supra28mhz+9mbRAM+OS3.2.2, CD32 & WinUAE

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Rob 
Re: Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
Posted on 19-Apr-2024 23:02:30
#2 ]
Elite Member
Joined: 20-Mar-2003
Posts: 6361
From: S.Wales

@Tpod

You could try the JP2 mod, which should allow you to use trapdoor memory as Chip RAM,. It's less work than the motherboard RAM upgrade and totally reversible if the A500 can't see remaining Megaboard RAM as slow RAM.

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Tpod 
Re: Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
Posted on 20-Apr-2024 17:17:10
#3 ]
Regular Member
Joined: 16-Oct-2009
Posts: 150
From: UK

@Rob

With my soldering skills I doubt putting the RAM directly onto the motherboard would work out too good , so JP2 mod is what I had planed (should of said altering to enable rather than upgrading the motherboard, to be clearer).

Even if I was good at soldering, going the JP2 route makes more sense … not only is it reversible & easier as you say, but importantly you can have a clock (via the trapdoor) which isn't possible if mounting ram chips onto the motherboard (can't add anything via trapdoor after doing that).

Last edited by Tpod on 20-Apr-2024 at 10:28 PM.
Last edited by Tpod on 20-Apr-2024 at 05:49 PM.

_________________
A1200+Mediator+Voodoo3+040+130mbRAM+0S3.9
A2000+Supra28mhz+9mbRAM+OS3.2.2, CD32 & WinUAE

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Tpod 
Re: Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
Posted on 20-Apr-2024 17:25:29
#4 ]
Regular Member
Joined: 16-Oct-2009
Posts: 150
From: UK

So I hooked out my old copy of Amiga Format Issue 31 (p 212 – 213) & also went online - https://archive.org to view Amiga Shopper Magazine Issue 27 (p 20-21 & 24-25).

It reminded me what put me off enabling Chip RAM with the MEGABOARD last time I had the idea.

Apparently although it may well sort of work (& not cause problems) the Amiga will only use 512Kb of the MEGABOARDS RAM (as Chip RAM). The A500 doesn't recognise the rest of the RAM at all after the mod, so instead of it being a 1-1.5Mb MEGABOARD it ends up effectively being a rather ordinary 512Kb board!

I have a spare 512Kb RAM board now so I'll use that instead, when I do the JP2 mod. I guess the MEGABOARD will join the rest of my never to be use again (at least by me) Amiga bit & bobs.

Last edited by Tpod on 20-Apr-2024 at 05:27 PM.

_________________
A1200+Mediator+Voodoo3+040+130mbRAM+0S3.9
A2000+Supra28mhz+9mbRAM+OS3.2.2, CD32 & WinUAE

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Rob 
Re: Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
Posted on 30-Apr-2024 20:39:57
#5 ]
Elite Member
Joined: 20-Mar-2003
Posts: 6361
From: S.Wales

@Tpod

It is possible to upgrade the Chip RAM to 2MB with the very expensive ACE2B from Individual Computers but it probably makes more sense to get a much less expensive 8MB Fast RAM board with or without IDE if you need more than 1MB.

ACE2B

ACE2B vodeo review

8MB Fast RAM

8MB Fast RAM + IDE

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Tpod 
Re: Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
Posted on 2-May-2024 19:37:12
#6 ]
Regular Member
Joined: 16-Oct-2009
Posts: 150
From: UK

@Rob

On the Chip RAM front, I find 1MB is adequate for general use & as I said the Rev 5 board is just a spare. The idea is to have 1MB Chip RAM enabled, so it's ready for use as a replacement if needed. The ACE2B would be nice to have but my pockets aren't deep enough!

I like the look of IDE68K + GottaGo FastRAM; I would be interested to know if anyone has a 68010 plugged into it?

_________________
A1200+Mediator+Voodoo3+040+130mbRAM+0S3.9
A2000+Supra28mhz+9mbRAM+OS3.2.2, CD32 & WinUAE

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Rob 
Re: Following an A500 1Mb Chip RAM Mod, can I still use a 1.5Mb Trapdoor (Zydec MEGABOARD) expansion without seeing smoke!?
Posted on 2-May-2024 20:10:05
#7 ]
Elite Member
Joined: 20-Mar-2003
Posts: 6361
From: S.Wales

@Tpod

Yeah, 2MB Chip RAM is probably handy if you're making music or animations but not useful in most other cases.

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