From: Brian Ketterling (tweel8502_at_hotmail.com)
Date: 2003-11-06 01:18:57
Just 2 cents... >From: Steve Judd <firstname.lastname@example.org> > >Yes, it is actually a two-byte opcode -- the PC counter goes to PC+2. >But nothing is actually done with the second byte; if it were e.g. pushed >onto the stack it might have been useful as a software interrupt... > >...Sorry to follow-up on my own message, but I forgot to mention that the >WDC >65816 data sheets call out BRK as two bytes -- "officially", it's >documented as a 2-byte opcode. I'm away from my 65816 docs, so I'm not sure, but I *think* on that MPU it is possible to pass the second byte as a parameter. >From: "Gideon Zweijtzer" <email@example.com> > >Of course, only the design team of the 6502 knows for sure what the >reason is... I think the design team was one or maybe two guys, working primarily on paper. >...The size of a 6502 >instruction is easily derived from the opcode by the following formula:.. That's pretty clever! -- Brian _________________________________________________________________ Concerned that messages may bounce because your Hotmail account is over limit? Get Hotmail Extra Storage! http://join.msn.com/?PAGE=features/es Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.