LZ: JR/opcode $18

[Prev][Next][Index][Thread]

LZ: JR/opcode $18

        okay, latley I've learned how to program in Hex using the Compiler
program on my ti-85. learning to program in Hex is really convienent for
small programs. I don't have to goto my comp all the time and assemble them.
It also has me hung up on one instruction, JR. I know the opcode for JR is
$18 and the next byte following it is how many bytes to jump foward or back.
But what has me confused is the two's compliment (what does that mean?!) and
in what format the next byte should be in (e.g. F8 = jump 8 bytes back in
the stack and 02 = jump four bytes foward) but how do I decide what to put
in there?(I know thats where to put the size of the jump!:))And in mnemonic
terms jump 8 bytes back is JR $F6+2 (which obviously equals and jump back 8
bytes, right?) I also know that $ equals "the current address". SO I think
my question is "how do i use the $18 XX opcode" and "what should I put in
XX?" AND "How do I two's compliment somthing?"


Thank you,
Joshua Lynch
josh17@winternet.com
Follow-Ups: