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emulator's memory.
All reads outside of the emulator's memory give back
$/0xFF bytes, while all writes outside of the
emulator's memory are ignored.
- Implemented malloc(), and free() in the SuB Suite.
In order to do this, I had to add support for a heap,
which I did by reserving the first 3 banks of the
address space (the first 192K), and by adding a
routine that finds the end of the RAM.
In this case, I set the starting address for the
routine at bank 3 (bank 4 with one indexing), but,
the routine's starting address isn't hardcoded, and
thus, any starting address can be passed as an
argument.
The routine uses the fact that we can now read/write
outside the emulator's memory, and also uses the
fact that writing outside the emulator's memory will
be ignored, and that reading outside the emulator's
memory will always read $/0xFF bytes, and uses that
to signal that it's reached the end of the RAM.
- Added a test program for getting the size of RAM
starting at address $/0x20000.
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instruction formatting simpler.
- Refactored the instruction table of the emulator's
assembler, it now has two parts, the addressing mode
bits, and the base value.
The base value is what's used to generate the actual
opcode, with the addressing mode bits telling the
assembler what addressing modes this instruction
supports.
The reason for doing this was to use less space. For
comparison, the previous version used 870 bytes for
the instruction table, while the new version uses
only 222 bytes. The new version is nearly 4 times
smaller than the pervious version.
- The B register based ALU instructions now use their
own addressing mode, and are specified by using 'b'
as the operand for those instructions.
For example, to add the Accumulator with the B
register, you now use "ADC B" instead of "AAB".
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- Changed the file structure of the SuB Suite, so that
all variable declarations, symbols, and constants
are in a single file.
- Moved the C library functionss into a separate
file, and made them use stack frames.
- Added support for using the emulator's assembler for
realtime debugging, to enter it, get in to stepping
mode by pressing Ctrl+s, press any other key, then
press F1,
The reason for having to press some other key before
pressing F1 is because it only allows entering the
assembler when the keyboard is not ready.
- Added the ".res" directive to the emulator's
assembler, the ".res" directive tells the assembler
to reserve however many bytes specified by the
operand.
- Fixed some bugs in the emulator's assembler.
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