Hallo Stephen, Thank you for answering the questions. But.... > > 1- The datasheets say the BRK and COP instruction are 2 bytes long when > > in native mode. Correct? > > Yup! >........ > > 3- (Only if answer for 1 = yes) Used in the emulation mode, the BRK > > instruction only must be 1 byte long. But still PC seems to be > > increased with 2 after the instruction: > > Hey, this one was pretty easy -- three Yups and two sentences :) ... in fact I hoped for a 'No' to the first question. The BRK instruction of the original 6502 is one byte long (At least I think). This means that in the emulation mode it must be one byte long as well. As it is two bytes long in the native mode it simply means that a assembler listing must look like this: .P6502 ..... ; for original 6502s BRK ..... .P65C02 ..... ; for 65C02 and 65SC02 BRK ..... .P816/E ..... ; for 65SC816 in emulation mode BRK ..... .P816/8 ..... ; for 65SC816 in native mode, 8 bits BRK $xx ..... .P816/16 ..... ; for 65SC816 in native mode, 16 bits BRK $xx ..... Correct? This also means that a RTI causes the CPU to return to the address represented by the dots in the first line after the BRK ($xx) instruction. Correct? For the others, I read your mail but as long I have problems with the above, I'll save them for another time in the future to reread them and apriciate them. Thanks. Groetjes, Ruud - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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