Your Commodore - Commodore Is Awesome

A
kmine
came round to borrow my type-
w writer. She wanted to produce a page
wof
quotes from her recent 'rave
ereviews'
to send to prospective em-
e
ployers. Several screwed-up sheet s of
A4 later, I went out for an emergency
k
supply of correction fluid.
s
This still didn't make the going less
a
heavy, so I volunteered to 'word-
gprocess'
it on my 64. She (my actress
o friend that is; my 64 has yet to deserve
athat
particular pronoun), wanted the
n reviews presented in a newspaper
aformat,
with different sized columns
cand
blocks all over the place. Trying to
tdo
this to 70 columns width on a 40
r
column screen was rather more
ecomplicated
than I had anticipated,
s
the text rapidly forming a literacydefying
tangle of bits of different sen-
s
tences. In the end we gave up. My
-actress
has not been to see me since.
f
"Oh, for an 80 column display
rmode!"
I thought. "Perhaps I can
iwrite
a sub-routine that will create
eone."
n I started with a simple routine for
d plotting user-defined characters on to
othe
hi-res screen. It was then necessary
fto
reproduce all the cursor routines of
the normal text screen, but
manipulating eight times as much
date. This was further complicated by
C64
Into the
Eighties
Are you fed up of enduring your C64's 40 column
screen? This program should bring you into the Eighties
in a .
fl as
By S.J. h Chance
the structure of the screen itself. The
hi-res screen consists of 'character
positions' of eight bytes, forming forty
8 X 8 grids across the screen. To
achieve 80 character positions, each 8
x 8 grid would have to contain two
_characters. This demanded much
ANDing„ °Ring, ROL_ing and
RORing.
Once you have successfully RUN
the loader program, the subroutine
can be initialised by SYS 49789. You
should now fi nd yourself looking at
the 80 column screen, blank except for
the 'READY' prompt, written in
teeny-weeny-letters in the top left hand
corner.
If you now type 'LIST', the first
thing you will notice is that the word
does not appear on the 80 column
screen. However, when RETURN is
pressed, the program lists in the usual
way. This is where you will discover
the limitations of the resolution of the
TAT. or monitor you are using. Having
only a humble black and white
portable, I find the text quite readable,
if you ae using a colour television, it
may help if you de-tune the channel
you are using to black and white.
The F8 key will toggle back to the
normal text screen, where you may like
to enter these lines of Basic:
10 GET AS: IF A$="" GOTO 10
YOUR COMMODORE november1986:14
20 PRINT Afi1 :GOTO 10
If you RUN this, any characters
you enter will now be output to both
the 40 and 80 column screens. This
includes changes in colour, but with
the limitation that each nybble of foreground
colour has to serve two characters.
For this reason, INSERT and
DELETE do not scroll the colour
memory as they do on the normal text
screen.
The character-set was originally
more curvatious, but I found that
squaring-up the corners and avoiding
diagonal lines produced a far bolder
image. As 8000L is intended for
word-processing, most graphics
characters would be redundant; thus
when they are encountered, the default
character of a reverse-space is printed.
If you wish to experiment with the
character-set, the relevant DATA
begins with the four double-zero's in
line 575.
The program occupies memory
from SC271) to SCBFF. Colour
memory starts at SCCOO, and the hi-res
screen uses the RAM behind the
KERNAL ROM at SE000. The subroutine
is wedged into the operating
system via the CHROUT vector at
$0326.
Perhaps next time one of your
friends needs a favour, you'll fare
rather better than I did!