Your Commodore - Commodore Is Awesome

U
assembler n entering machine code data
is l a real problem. Since machine code
is
e
simply a series of numbers, entering
them into your computer leads to all
sorts
s
of errors, resulting in your
program's s total inability to functions.
y Your Commodore uses Basic
loaders o to help people to enter
machine u code programs from the
magazines.
h
These Basic loaders hold
the numbers that make up the machine
code
a
program in a line of data, the last
number v being a checksu in. The Loader
program e when RUN, reads the DATA
into a memory, adding each number
together, c then the total of each line is
compared c with its checksum, if they
are
e
not the same then you have done
something wrong.
s In the March 1986 issue of Your
Commodore s we printed a Basic
program t for the 64 (Datamaker) that
would o read a machine code file from
disk a and generate a machine code
program.
n
This worked fine except for a
couple of small problems. Firstly the
program was very slow. Secondly, you
had to have a disk drive to use it.
With this article we are printing
two new machine code to data
statement conversion programs. One
of them is for the C64 but this time the
program is written in machine code
and will now take machine code from
memory as well as from disk. The
second program is for the Cl28, this
program isn't quite as fast as the one
for the C64 but it does have the
advantage that it generates its own
SAVE routine at the end of the data so
that, when RUN, the program will
SAVE the machine code on to disk.
C64 Data Maker
As I mentioned earlier, this version of
the data maker program is better than
the old one. A further facility that has
been added is an extra check in the
C64 AND C1281 CI
Datamaker
Turn your machine code into Data with these two
programs from M. Catley and K. °non.
loader program. If, in the old version
of the program, you omitted a number
from a line of DATA, the computer
would read the checksum and try to
POKE it into memory. Since the
checksum is usually greater than 255
this resulted in an illegal quantity error
in the line that held the POKE
statement.
This new version of the program
has a check that stops the program if
the number to be POKEd into memory
is greater than 255, giving the line from
which the DATA was read, not the line
of the POK E statement. As you can see
this makes finding typing errors even
easier.
The CM Datamaker is presented
here in the form of a Basic loader. In
fact the program was used to make this
loader.
As already mentioned this is a
machine code file that should be
WADed and RUN at memory location
49152 ($C000 hex).
To start the program you enter the
following commands:
NEW
SYS 49152
As soon as you press RETURN the
screen will clear and a promt 'INSERT
READER PROGRAM Y/N' will
appear. If yes is selected the simple
loader program shown in Figure I will
be entered into memory.
Data maker will work out the last
line of any program already in
YOUR COMMODORE november 1986:76
memory, add 10 to it and start its own
numbering from there. This allows
DATA statements to be added on to
an existing program.
Once the reader has been entered
or if no (N) was selected a second
prompt •SELECT DISK OR
MEMORY' will be displayed.
If MEMORY is selected further
prompts for start and end addresses
will be displayed. These numbers may
be entered in decimal or in hex by
prefixing the number with a dollar
sign.
If DISK is selected a filename will
be requested.
Once the end has been reached
Data Maker will insert the number of
blocks, line number and memory start
address into the reader part (only if the
reader was entered of course.) It will
then return to Basic with the READY
prompt.
Data Maker 128
Data Maker 128 is a utility program
for the C128 computer with a disk
drive. The program will take any file,
the SOURCE program, from the disk,
convert it into DATA statements and
write it back to the disk under a
supplied filename, the TARGET
program. You will also be requested to
supply a START LINE NUMBER and
an increment value for the DATA
STATEMENTS. Twenty individual