Author
| Is 28 KB RAM the maximum that the MSX-BASIC could direct use?
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Yukio
msx professional
Posts: 770 |  Posted: January 22 2008, 01:21 |
There are some references to this amount of memory on MSX.
Sure, this when someone is not using a attached disk-drive unit.
The use of additional memory for the Screen (16KB VRAM for MSX1 and 128KB VRAM for MSX2/2+) could help a little into this situation.
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PingPong
msx professional
Posts: 869 | Posted: January 22 2008, 08:34 |
msx vram is not directly usable as main ram. this is because the vram is not accessible directly from cpu.
the cpu does not 'see' the vdp vram as a ram instead see only the vdp. when accessing vram cpu ask the vdp to make available the byte needed with a slow and relatively complex sw protocol. Because of this there is no way to execute code, or basic program in vram.
(At least in a regular msx)
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cax
msx professional
Posts: 1009 | Posted: January 22 2008, 13:37 |
Yukio, MSX2 has a virtual disk in MSX-Basic that uses the rest of RAM.
As for VRAM, I think Basic doesn't use it for program/variables storage just because it can be easily erased by graphical commands.
And now, what you wanted to say ? Sure there exist techniques that make use of VRAM for various purposes - e.g. hacked 128K ROM versions store some parts of the game in VRAM and copy them into RAM when needed.
Finally, you can store your data in VRAM if you want by just using series of VPOKE, or even use BSAVE,S
Maybe your point is to enlighten us by telling us about your fresh invention ?
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