Advertisement
ATARI Light Pen Operator's Manual
APPENDIX Q - NOTES ON MEMORY CQNSERVATIQN/PENBUF MEMORY USAGE
In most of the demonstration programs in this manual<
the PENBUF
routine is appended as a part of the program. If you are trying to
conserve memory for a particular program< there are tuio uays you can
do
it.
You can use the PENBUF loader contained in the ATARI Light Pen
Demonstration Cassette program for the 8K version of PALLET. This
occupies fewer bytes than the 16K PENBUF loader used in the other demo
programs and yet performs the same function (it also loads faster).
The only difference is that the decimal values in the loader have been
converted into characters and stored in the BASIC string A*.
The other way to conserve space is by leaving the computer console on
and not disturbing Page 6. As long as the power stays on>
the data in
the memory areas will remain the same unless specifically changed by
the programs running in the machine. The area used by PENBUF is not
used by the operating system< so any program segment loaded there will
stay undisturbed as long as the power is on.
The loader segment in each program from line 9000 onward places the
PENBUF data into hex page 6 in the machine. It will not function
anywhere else. If no other programs use this same area<
you can
load and run the loader routine once. Then you can use the USR
calls to that area (decimal 1536) in other programs loaded later
without needing to include the PENBUF loader within those other
programs. Therefore you will have more room left in your program
to use for other purposes.
The PENBUF routine will remain intact as long as the computer remains
powered up. But you must remember to reload and run the loader
routine before trying to use PENBUF within other programs< and do not
POKE any data into locations 1536-1791 because this would disturb the
PENBUF routine.
Memory Conservation - 61
Advertisement
