Jump
Jump is a three-decle opcode that is represented as one of several different possible mnemonics, depending on the flags indicated in the second decle of the opcode. The opcode breaks down as follows.
Format - Decle #1 Format - Decle #2 Format - Decle #3 0000:0000:0000:0100 0000:00rr:aaaa:aaff 0000:00aa:aaaa:aaaa
where:
rr indicates the register into which to store the return address such that: rr == 00 indicates to store return address in register R4 rr == 01 indicates register R5 rr == 10 indicates register R6 rr == 11 indicates that the CP1610 should not store the return address, signaling a Jump without return
ff indicates how to affect the Interrupt (I) flag in the CP1610 such that: ff == 00 indicates not to affect the Interrupt flag ff == 01 indicates to set the Interrupt flag ff == 10 indicates to clear the Interrupt flag ff == 11 unknown opcode (behavior unknown!!)
aaaaaaaaaaaaaaaa indicates the address to where the CP1610 should Jump
This opcode is often represented as many different mnemonics, to make life a little easier for the programmer. The mnemonic used to represent this opcode depends on the combination of the rr and ff parameters mentioned above, according to the following charts.
Mnemonics From Parameters
Mnemonic | rr | ff |
---|---|---|
JSR | 00,01,10 | 00 |
JSRE | 00,01,10 | 01 |
JSRD | 00,01,10 | 10 |
J | 11 | 00 |
JE | 11 | 01 |
JD | 11 | 10 |
Invalid Opcodes | 00,01,10,11 | 11 |
Parameters From Mnemonics
rr == 00 | rr == 01 | rr == 10 | rr == 11 | |
ff == 00 | JSR R4, $aaaa | JSR R5, $aaaa | JSR R6, $aaaa | J $aaaa |
ff == 01 | JSRE R4, $aaaa | JSRE R5, $aaaa | JSRE R6, $aaaa | JE $aaaa |
ff == 10 | JSRD R4, $aaaa | JSRD R5, $aaaa | JSRD R6, $aaaa | JD $aaaa |
ff == 11 | unknown opcodes |