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AuthorTopic: 1 MB (9.5 MB maximum)  (Read 1332 times)

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Offline sim085

1 MB (9.5 MB maximum)
« on: March 10, 2011, 09:46:09 AM »
Hello, was reading the Wikipedia page on the A500+. Here, in the specifications section, I found the following; "Memory: 1 MB  (9.5 MB  maximum)". Now, from the little I know, an A500+ can have more then just 9.5 MB of RAM. Then what is this referring to? Maybe only ChipRAM? If yes, is this so, and why?

http://en.wikipedia.org/wiki/Amiga_500_Plus
 

Online zipper

Re: 1 MB (9.5 MB maximum)
« Reply #1 on: March 10, 2011, 09:50:30 AM »
2 MB Chip and 8 MB Fast is the normal max, with some tricks you may get still a little more Fast. With an accelerator  you may get still upto 128 MB additional Fast.
 

Offline psxphill

Re: 1 MB (9.5 MB maximum)
« Reply #2 on: March 10, 2011, 12:48:42 PM »
Quote from: sim085;620838
Hello, was reading the Wikipedia page on the A500+. Here, in the specifications section, I found the following; "Memory: 1 MB (9.5 MB maximum)". Now, from the little I know, an A500+ can have more then just 9.5 MB of RAM. Then what is this referring to? Maybe only ChipRAM? If yes, is this so, and why?
 
http://en.wikipedia.org/wiki/Amiga_500_Plus

It's wrong.
 
The A500+ comes with 1mb onboard & can have an extra 1mb in the trapdoor. Without a CPU upgrade it can then have up to 8mb on the expansion bus. Which brings the total to 10mb.
 
With a 68020+ CPU upgrade you can have more (the space between 0x10000000 & 0x80000000 ~1.75gb is probably free).
 
Officially the original a500 is limited to 9mb, 512k onboard, 512k in the trapdoor and 8mb on the expansion bus. However I had a 2mb agnus which still allowed the trapdoor expansion to be used. IIRC I had 2mb chip, 1.5mb in the trapdoor, but only 2mb on the expansion bus (might have been 4mb but it was expensive ZIP ram and I don't think I could afford it at the time).
 

Offline Zac67

Re: 1 MB (9.5 MB maximum)
« Reply #3 on: March 10, 2011, 10:02:24 PM »
I think the article should stick with the 'unmodded' expansion variants, i.e. an original A500 can have 1 MB chip + 8 MB fast and a 500+ 2 MB chip + 8 MB fast - this is what it was designed for. Where the 9.5 Megs come from is beyond me (sounds more like a 500 than a +).

With some address decoding trickery (Gary adapter) you could possibly add some 1.8 MB Ranger as well. The largest accelerator boards support up to 128 MB and from there on it starts getting hypothetical - of course you could adapt a 2000 board, or build your own accelerator but that's probably extremely rare. All this deviates more and more from the original design and isn't really what the article should be about.
 

Offline Digiman

Re: 1 MB (9.5 MB maximum)
« Reply #4 on: March 11, 2011, 12:25:46 AM »
A500+ motherboard can handle 10mb without modification and that's what it should say. 68020 and onwards=modification.