RE: MAX-carts

From: Marko Mäkelä (
Date: 2002-01-22 09:47:09

On Tue, 22 Jan 2002 wrote:

> 2) serial devices seem not to be there, only tape device #1 seems to be
> there
> 3) RS232 routines seem to also be missing 

That makes sense, as the UltiMax lacks the $dd00 CIA.

On Tue, 22 Jan 2002 wrote:

> The VC-10 need at least 40*25 = ~1KB space for the screen, then 256 bytes
> zeropage and 256 bytes stack. Means only 512 bytes are left. Not much IMHO?
> So that's why the extra 2 KB are needed. 

To be more accurate, the space below $0800 is initialized in a similar
fasthion as it is on the C64.  The on-cartridge RAM should map to
$0800-$0fff, as the UltiMax reports 2047 bytes free with this cartridge
plugged in.

> That VC-10 shows that only 2 KB are free could mean that is has dedicated
> the "left over" 512 bytes for other things. You mentioned yourself the
> datarecorder works fine so at least we need some space to buffer data.

The 192-byte cassette buffer for OPEN/PRINT#/GET#/INPUT#/CLOSE operations
is located at $033c on the C64.  When LOADing and SAVEing programs, the
cassette buffer is only used for the file name.

> Then I have question myself: I assume that some (maybe most) of the games
> are graphical. IMHO this would mean that all these card must have at least 8
> KB of RAM onboard. Is this true or am I missing something?

Character graphics, I would say.  Also the VIC-20 has only 5 kilobytes of
"graphics memory".  Note that the ROMH chip can hold 4k of (predefined)  
graphics that is mapped at $2000 or $3000 (I forgot which) in the VIC-II
address space.


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