New Amiga 500(plus) trapdoor RAM

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cmorley
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New Amiga 500(plus) trapdoor RAM

Post by cmorley » Fri Mar 09, 2018 2:08 pm

Time to give the Amiga some love. :)

My new trapdoor RAM expansion prototype is working and seems stable. 2MB split as +0.5MB chip RAM and 1.5MB ranger/slow RAM on an A500.

A500+ compatibility is on the todo list... ranger RAM on a Plus isn't so easy so I'll go for +1MB chip first for a total of 2MB chip.

Trapdoor RAM card and Gary adapter:
Photo1267.jpg
Haha! It works:
Photo1268.jpg

Commie_User
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Re: New Amiga 500(plus) trapdoor RAM

Post by Commie_User » Wed Mar 21, 2018 10:06 pm

That ain't not bad!

What are you doing on the Amiga that works better now?

cmorley
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Re: New Amiga 500(plus) trapdoor RAM

Post by cmorley » Wed Mar 21, 2018 10:43 pm

There are lots of games which will make use of more memory for better graphics and sound or less disk swapping. Mostly they use only another 0.5MB I think.

Workbench however will see and use all the memory for the full 2.5MB. This is a huge increase over the original 0.5MB. You can run multiple instances of programs which barely run on a 0.5MB system like Deluxe Paint 3 for example. Sizeable RAM disk too is possible.

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trixster
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Re: New Amiga 500(plus) trapdoor RAM

Post by trixster » Thu Mar 22, 2018 11:01 am

Thumbs up for some Amiga love! :D
A3020 | A3000 | A420/1 | BBC B + 128K RAM/ROM + 20K Shadow + Pi0 + VideoNuLA
Master Turbo + DC + BeebSID | Atom | A4000 060 | A3000 060 | A1200 060 | A500
Atari Falcon 060 | Saturn | PS1 | SNES | CPC6128 | C64 | 3DO | MD | Jaguar

cmorley
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Re: New Amiga 500(plus) trapdoor RAM

Post by cmorley » Thu Mar 22, 2018 7:29 pm

I got it working with the Amiga 500+ too. Without modification it gives 1MB extra chip. With a gary adapter, a pin lift and 2 fly leads you get 1MB slow memory too.

A500+ with 3MB:
Photo1278.jpg
My grotty corrosion repaired A500+ motherboard:
Photo1279.jpg
Workbench:
Photo1280.jpg

cmorley
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Re: New Amiga 500(plus) trapdoor RAM

Post by cmorley » Thu Jun 07, 2018 6:39 pm

The production version PCBs are in now so I can post some pics of those if anyone is interested?

Tested now and compatible with A500 issue 3, 5 & 6 as well as the A500+

cmorley
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Re: New Amiga 500(plus) trapdoor RAM

Post by cmorley » Fri Jun 08, 2018 4:16 pm

Memory board installed in a A500 6A & configured for the full 2MB. The fly lead goes off to JP2 which is the jumper normally used to select if you want the trapdoor memory to be slow/ranger RAM or chip RAM. The fly lead allows it to provide both types of memory. The Gary adapter is required to get additional address lines which aren't available on the memory expansion connector. Needed for the full 2MB.

Empty DIP socket is for a realtime clock chip (RTC) and the battery holder is for the RTC - standard CR2032.

Board:
Photo0207.jpg
Fly lead:
Photo0212.jpg

cmorley
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Re: New Amiga 500(plus) trapdoor RAM

Post by cmorley » Fri Jun 22, 2018 7:16 am

Now available if people are interested?

I won't post in For Sale because it isn't Acorn.

Check the website for more details http://www.boobip.com/hardware/A500_2MB. It also has all my Acorn upgrades. Or post/PM me.

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