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t.mini-screen
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2022-08-26
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M I N I - S C R E E N
by Dave Moorman
MINI-SCREEN is a text-screen
bitmap display routine the puts Mini-
Bitmap images on the screen. This is
an ML module that must be bloaded to
memory before use. We have included
two versions -- SCREEN192.ML and
SCREEN158.ML. The number is the memory
page to which the module must be
beloaded.
SYS57812"SCREEN192.ML",dv,0
POKE780,0 ---
PO781,0
POKE782,192
---
SYS65493
SC=192*256
---
SETUP
-----
SYS SC,X,Y,COLOR
where X is the text column
Y is the text row
of the upper left corner
of the mini-screen
COLOR is the foreground color
of the mini-screen
The mini-screen needs to be placed
on the screen with this command. Also,
a custom font location must be
established (for instance at Page 56)
and switched to (by poking 5353272 the
the appropriate value). The font area
is where the mini-bitmap files are
bloaded.
CLEAR
-----
SYS SC+3,SWITCH
where SWITCH is either 0 or 1. If 0,
the mini-bitmap area is filled with
0's -- showing the background color.
It 1, the area is filled with 1's --
showing the foreground color. If you
have already bloaded a mini-bitmap
file to the font, you will not want to
do this.
PLOT
----
SYS SC+6,X,Y,P
where X is the pixel column (0-127)
Y is the pixel row (0-95)
P is the pixel to plot (0-1)
Not a very fancy plot routine, but
servicable.
MPLOT
-----
SYS SC+9,X,Y,P
where X is the pixel column (0-63)
Y is the pixel row (0-95)
P is the pixel value (0-3)
This is a multi-color text mode plot.
When using SETUP, the color must be
COLOR+8 to enable the MC Text Mode.
Also, 53280-53282 must be set with the
three background colors.
COPYMEM
-------
SYS SC+12,FPG,TPG,PGS
where FPG is the From Page
TPG is the To Page
PGS is the number of Pages to
copy.
This is a very fast copymem because
it doesn't mess around with odd
numbers of bytes -- copying whole
pages.
With this module, you can build
your own mini-bitmap screens. A couple
of secrets:
These bitmaps use all but 64
characters of the font. So when a
MINI-BITMAP is made from a SHP or
Doodle graphics file, the alphanumeric
characters are only capitals, and all
reversed. The "blank" screen, except
where the mini-bitmap is displayed, is
all CHR$(32)'s, and so is also
reversed.
Thus, you can have one color for
the screen, one for the background
(often the black pixels on the
screen), and another color for
non-screen area of the screen. See the
Cheering Crowd graphic of The Zuccinni
Song for an example.
Also, in that example, two mini
screens are placed side by side,
effectively doubline the "crowd."
We have included a very simple
Run It program that puts the
mini-screen on the screen with a
picture of a Commodorean celebrity.
Look over the code to understand how
it works.
This module is at the heart of the
Zoetrope movies on issue 246 -- and we
will have more fun with it in the near
future. If you would like to take a
crack at making your own movies or
mini-slide shows -- here is what you
need.
DMM