Posted By
Jay
on 2005-12-06
21:44:59
|  RAM expansion for Plus 4?
I know REUs were big on the C64/128 machines... was there ever any RAM expansion cartridge/software support for the Plus 4 or C16?
Just curious...
Jay
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Posted By
JamesC
on 2005-12-06
22:29:49
| Re: RAM expansion for Plus 4?
There were commercial RAM expansions for the C16, to bring them up to 32K or 64K.
At one time, there was a 256K expansion available from an enthusiast group. (Syngery, I think.) The diagrams and parts list should be available on the 'net. Sadly, the group no longer supplies ready-assembled units. 
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Posted By
Jay
on 2005-12-08
18:31:36
| Re: RAM expansion for Plus 4?
Wow, a 256 to 1 meg expansion - sounds great!
Any idea how many of these are being used out there, what software supported them? Were these handled by the system in a similar way to the C64/128 expansion units (no direct access, have to transfer data to/from main memory)?
Too bad the schematics look way too complicated for me to build!
Jay
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Posted By
siz
on 2005-12-09
03:11:35
| Re: RAM expansion for Plus 4?
There are plenty of software for the 256k RAM expansion, I don't know about the 1Meg version. These expansions work like the +60k on C64: you can switch the actually used 64k of the total memory. And you can select the switch boundary between $1000 and $4000. Memory below the boundary is not switched it's always the same (default) bank so you can place your software and variables there. This is the expansion made by Hannes.
There is an other 256k expansion made by Csory which is compatible with the Hannes one but In this case you can select a 16k RAM bank and switch any 16k slice of the 256k RAM there.
In both expansions you can set the TED to always read the default bank.
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Posted By
indi
on 2005-12-12
13:01:52
| Re: RAM expansion for Plus 4?
I just got a 512Mb one for the C64, nice little unit.... No idea what I'll use it for though!!
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Posted By
SVS
on 2005-12-13
04:13:41
 | Re: RAM expansion for Plus 4?
I own and use a 256K Plus4 with Hannes expansion.
I don't think however that it is compatible with Csory' project. If I'm not wrong, only the OS96 (opeating system mod) has a compatibility with it.
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Posted By
siz
on 2005-12-14
03:41:56
| Re: RAM expansion for Plus 4?
Csory's expansion can handle all functions of the Hannes one but adds one more register at $fd15 to handle the memory window. To use the memory window first you have to fill $fd15 and then set bit 5 and 4 of $fd16 to 10.
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