[Coco] Semigraphics modes examples

[Arthur Flexser]

Semigraphics-4 is the easiest to use, since Basic has the SET and RESET
commands to access it.  This is the only semigraphics mode the CoCo 3
allows.  Semigraphics-4 uses the standard text screen, and allows the
screen to contain both normal text and semigraphics characters that divide
the space of a letter into quarters.  Each quarter is a small colored or
black region, with 8 colors plus black allowed.  No mixing of pieces of
letters with the colored small blocks within a letter-sized area, nor
mixing of different colors, both of which higher semigraphics modes allow.
The other semigraphics modes are not supported within Basic and must be
accessed through pokes or machine language.  They divide the screen up into
finer areas that can be filled with colored blocks and/or pieces of letters
that might or might not combine to form a complete letter.  In these modes,
a letter-sized area is represented by several bytes rather than a single
byte as in Semigraphics-4, so such an area could contain pieces of
different letters along with some colored areas.  The Getting Started book,
if I recall, had an appendix that described the different semigraphics
modes in some detail.  (Semigraphics-6 never worked right, though, and was
tossed on the B-model CoCo 2s and replaced by true lowercase text that
was accessed in the same manner that previously threw you into
Semigraphics-6 mode.)

Though some games and rompacks used the higher semigraphics modes, they
were generally less flexible from a programming standpoint than regular
graphics modes, and were never very popular with software authors.  Steve
Bjork's Audio Spectrum Analyzer rompack is one example of a program that
uses a higher semigraphics mode.  Another semigraphics rompack was for
controlling Plug 'n Power modules.  I imagine there are other examples of
semigraphics software in the database here.  I recall one well-done pacman
game that used one of the higher semigraphics modes, though I don't recall
its name.

I seem to recollect that someone here on the list (Robert Gault, maybe?)
came out a while back with a utility that allowed easy use of the higher
semigraphics modes.

Art



On Fri, Jul 31, 2015 at 5:56 PM, Stephen Robinson <
nix.thinkpenguin at gmail.com> wrote:

> Hello all,
>
> Long time lurker here. I am a latecomer to the Coco scene. They had
> been out of production for a long time by when I got my start. When I
> was a pre-teen back in 2005-ish, my father gave me a Coco 2, some
> cassette tapes, a stack of old Rainbow magazines, and a pocket
> reference guide. I managed to hook it to our TV by taping some wires
> together. And after typing in:
>
> 10 PRINT "HI"
> 20 GOTO 10
> RUN
>
> I was hooked! End result: I learned to program from Rainbow magazines,
> asked my father for more Coco stuff, and have gone one to study and
> get a job in Computer Science.
>
> I don't really have much time at all for Coco's anymore (sadly). But
> there was one especially large lingering question in my mind. What
> were the semigraphics modes? I heard much about them in the Rainbow
> magazines. How the Coco 3 didn't support them (all). How the size of
> them was odd. Etc.. But never could I find an example to run.
>
> So, if nothing more than to finally solve this childhood mystery, is
> there some reference which I could see to finally explain these
> magical text graphics modes to me?
>
> Thanks,
> Stephen
>
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>