More 6502 Updates

Further improvements on the Virtual 6502 suite.

Illustation: MOS 6502 MPU

Never at a loss to improve and always afraid to miss out on features or correctness ;-), I added another bunch of improvements to the Virtual 6502 suite.

This time, it has been about the emulator, which received a watchdog to monitor breakpoints and other conditions (like register contents or stack underflow), and support for interrupts. Also, stack operations in conjunction to the implementation of the break flag have been improved. (Moreover, all the applications now enjoy — hopefully as much as the user — fancy UI buttons and custom dialogs. Besides looking period appropriately pretty — this is sort of a sympathetic restoration —, these also provide some extended functionallity that is essential to some of these improvements, like the dialog for editing the watchdog’s conditions.)

In addition to this, the 6502 Instruction Set Sheet now features all kind of information on “illegal” opcodes: there’s now a checkbox below the instruction table to include them in the view, a new section with details on those undocumented instructions, and two three more decoding tables showing, where these fit in, and providing deeper insight into the internal operations.

I guess, next steps will be to implement support for these illegal opcodes for the emulator, assembler, and disassembler as an option.