2014-05-24 07:21:50 -07:00

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This directory holds files likely to be of use to you in developing your own
programs. The contents of each file is summarized below.
c64_0.oph: A Commodore 64 equivalent to a modern compiler's "crt0.s" - it
contains a .PRG file header, a short BASIC program that launches
the machine language program, and a prologue and epilogue that
prepare memory for your use and then clean it up again when you
are done. Memory locations $02 through $8F on the zero page are
available for your use, and the program lives at the beginning
a contiguous block of RAM from $0800 through $CFFF. The BASIC
ROM is swapped out of memory (leaving $A000-$BFFF as RAM) for
the duration of your program. BASIC's working storage on the
zero page is backed up in the RAM underneath the KERNAL ROM
while your program runs.
c64kernal.oph: A collection of standard aliases for the KERNAL routines on the
Commodore 64. Names for these routines have been chosen to match
the Commodore 64 Programmer's Reference Guide. Additional useful
constants are defined for the character codes for color changes
and case-changing.
libbasic64.oph:A still-experimental set of macros and routines for exploiting
the software floating point routines in the Commodore 64
c64header.oph: A much simpler Commodore 64 header that does nothing but jump
directly to your code. Useful for small programs or those that
intend to interface with BASIC.
vic20.oph: A simple header for the unexpanded VIC-20. Equivalent in
behavior to c64header.oph.
vic20x.oph: A simple header like the two above, but for expanded VIC-20.
nes.oph: A somewhat skeletal collection of aliases for the PPU registers
on the Nintendo Entertainment System. These names were chosen
to match the constant names given on the NESdev Wiki.
stella.oph: A collection of aliases for the registers of the Atari 2600.
These names were taken from the "Stella Programmer's Guide" and
are in wide use amongst developers and code analysts alike.