Target system features:
- 64Kb RAM (full addressable on write, visible on read banking out ROM)
- 32Kb ROM (not necessary for first firmware developing phase: full RAM operations)
- programmable glue logic (PLD)
- modularity for CPU, I/O, video and audio controllers
- arduino as debugger, memory inspector and injector, code loader, execution stepper
- 2 clock speeds switchable at runtime: slow (arduino driven) and fast (4 MHZ fosc)
- configurable breakpoints at slow speed (arduino controlled) to stepping execution code
- SPI and serial I/O
- PS/2 keyboard
- SD card as storage device
Constraints:
- through-hole only components
- 4Mhz CPU clock
- WDC W65C02S CPU
Software developing:
- cross IDE and assembler
- direct RAM programming (no need to remove and program the ROM for each code modification)
- stepping execution and breakpoints
WDYT #1 - How to get CPU regs values from Arduino during debugging?
What strategy we can use to inspect, from Arduino, the values of CPU internal registers (A, X, Y, status, stack pointer) when stepping the code execution?
We can play with: SYNCH, RDY, BE, PHI2, NMI (see mother board H5 on schematic).
So... What Do You Think?