I've been writing some simplistic ZX Spectrum programs for a bit now,
and
feel I am ready to move on to trying to write something for the SAM (one of
which I actually own). Of course I understand that there isn't any extra
complexity in writing for the SAM (at my level) once the graphics mode has
been set up, but there is a lot of extra complexity in being able to quickly
write code and try it out. So while I'm here : please can a snapshot file
format be added to a SIM Coupé? Only loading would be fine . . .
Anyway, I am wondering about graphics modes. Since the drafts for a new
technical manual available on the 'net are broken with my current PDF viewer,
I was hoping someone here could help.
First : are there any speed differences between the graphics modes? I
understand that Mode 1 is slowed down deliberately to loosely approximate a ZX
Spectrum, but are there any other differences in other graphics modes? How
many t-states do I get per scanline, and are there still 312 of them?
Second : does altering the palette have any effect in Modes 1 & 2? Does
Mode
3 simply only look at the first 4 palette entries, or is it more complex than
that?
Third : is whichever page of memory which doesn't contain any of the
screen
still contended? Am I right in thinking that the only effect of contention is
to frequently round t-states up to the nearest 4?
Finally : thanks for reading this, and thanks some more for any
responses.
-Thomas
