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2020-10-04- Added support for reading, and writing outside themrb0nk500
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.
2020-08-08- Refactored the opcode table, in order to make themrb0nk500
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".
2020-08-08Did a ton of stuff.mrb0nk500
- 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.