LOW TO HIGH CONVERTER by Richard Karsmakers and Sven Krüppel
Originally published in ST NEWS Volume 1 Issue 4, launched on
September 7th 1986.
In Level 16, a 16-bit dedicated computer magazine (which I've
heard has ceased to exist), of March 1986, I saw a useful
conversion routine to convert Neochrome low resolution pictures to
32000 bytes High resolution screen data. It was very nice, but
awfully slow (converting a picture took about half an hour). Also,
the user had to create a Degas picture from those 32000 bytes by
Since I thought this program was much, much too slow (mainly
because it used the wrong Basic language) and not complete enough,
I decided that a better version of the program had to be written,
using File Selector Boxes, Alert Boxes, etc. And it had to be
faster, too. So we decided to use GfA Basic, and rewrote Sven's
basic routine into a more complete, faster concept. The program is
added on the disk on which you've found this bulletin, and is
called "CONVERT.BAS". It is the first program to be delivered with
ST NEWS, the first in a - hopefully - long row. At the moment that
this article was written, a good friend of ours was working on a
deluxe C version of the program. We don't know yet if we will
publish it in ST NEWS, but we will try to obtain it very hard.
Converting might then turn out to be a question of seconds rather
then minutes (now, it still takes 6½ minutes to complete one
We regret that we cannot give you any details about the actual
conversion routine; that's because we didn't get the picture from
Sven - if you know what I mean. It's just Sven's routine,
converted to GfA Basic. All the POKE commands from ST Basic (which
are 16-bit POKEs) had to be converted to DPOKE in GfA (because a
normal POKE in GfA is 8-bit, whereas DPOKE is 16 and LPOKE is 32
bit), and the IF-THEN routines had to be adapted (with GfA, all
arguments have to be on different lines!). At first, that caused
quite a lot of trouble, but we managed (as you can see).
A note to the ALERT command may also be written down here: as you
may remember, in Volume 1 Issue 2 of ST NEWS, Delta Software
Productions wrote a review of GfA Basic, in which he forgot to
explain the first variable ('n', remember?) of the command:
Well, this 'n' can have four values, ranging from 0 to 3:
0 Normal Alert Box
1 Watch out! Alert Box
2 What's happening? Alert Box
3 Stop right there! Alert Box
In the converter, we used number 1 and number 3. It also took
quite a while to find out how we could POKE on 16745024! In ST
Basic, it was normally possible to POKE there, but in GfA you need
to enter the supervisor mode. Therefore, SPOKE was introduced. Was
I glad I had a list of GfA commands at hand (which you will find
elsewhere in ST NEWS as well, with the GfA Basic Tips & Tricks)!
If you have discovered any nasty bugs in our converter, or if you
think something should be altered/debugged/improved/adapted,
please contact us at our correspondence address.
Since we hope to publish some more GfA Basic programs, we also
hope that you will help us. Start writing nice utilities in this
versatile language and send them to us, wo we can use them in a
next issue of ST NEWS. At the moment, we are writing a Disk sorter
ourselves, which will enable you to create files of all your
programs on all your disks. But it might take a while before it's
finished! Ofcourse, you may also send 100% basic games.
The text of the articles is identical to the originals like they appeared in old ST NEWS issues. Please take into consideration that the author(s) was (were) a lot younger and less responsible back then. So bad jokes, bad English, youthful arrogance, insults, bravura, over-crediting and tastelessness should be taken with at least a grain of salt. Any contact and/or payment information, as well as deadlines/release dates of any kind should be regarded as outdated. Due to the fact that these pages are not actually contained in an Atari executable here, references to scroll texts, featured demo screens and hidden articles may also be irrelevant.