cpu6502_tc - R6502 Processor Soft Core with accurate timing

The implementation of the interrupt instruction BRK and hardware signals IRQ / NMI is incorrect and will produce incorrect results and/or hang the core in every case.

See below for more information about that. Bugs are now fixed in the new release (17-Apr-2008).

BRK:

• Stack Pointer incorrectly grows up - not down
• The "B" flag is not set and stacked up
• Writing to the stack produce misalligned relationchip between addresses and data

IRQ:

• Stack Pointer incorrectly grows up - not down
• Writing to the stack produce misalligned relationchip between addresses and data

NMI:

• Stack Pointer incorrectly grows up - not down
• Writing to the stack produce misalligned relationchip between addresses and data