[zxspectrum] Re: R: Re: COSMOS
- From: Zurillion <zurillion@xxxxxxx>
- To: zxspectrum@xxxxxxxxxxxxx
- Date: Fri, 26 Oct 2007 00:24:53 +0200
Il giorno 25/ott/07, alle ore 20:49, Massimo Raffaele ha scritto:
[snip]
This is something not everybody knows:
- the Spectrum has *true* 48KB RAM physical memory (memory chips)
- the Commodore 64 has *true* 64KB RAM physical memory (memory chips)
So the C64 has *more* memory than the Spectrum available to machine
code programming (I'm NOT writing about the amount accessible to
BASIC programming).
This HUGE RAM is available via banking out the following ROM's from
the address space: the 8KB BASIC ROM and the 8KB Kernel ROM.
Knowing this, you can understand how they managed to allow 48KB
programs to fit in the emulated Speccy :-)
Max
Max, but, as far as I remember, there is still one more thing:
weren't in the C64 many custom chip and I/O control registers ( for
VIC-II and SiD, for example) memory mapped in various scattered
places around the RAM, so that it couldn't be used as a single
contiguous chunk?
If this is true, I wonder how the emulator managed to load a full 48k
program ... maybe it implemented some primitive form of MMU? ;-)
Cheers,
Giovanni
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