Jeff: You owe it to yourself to buy the PPC CDs. Among other things, they contain the _entire_ collection of PPC journals in PDF format.
Now to answer your question, here's an excerpt from V6N5P21:
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Three byte local GTO's and local executes contain one byte from the Postfix Table which specifies the label of interest. The remaining bits are used to remember the address of the label once it has been found by a LBL search. This technique allows improved execution speed since the slow label search process is only done once. On all subsequent executions of the GTO or XEQ function the location of the label is known and no search is needed.
A three byte GTO 22 instruction has the following form immediately after it has been keyed into progam memory:
Function Byte 1 Byte 2 Byte 3
GTO 22 D0 00 16
If LBL 22 was the third byteof a register, 30 registers away from the GTO 22 instruction, the GTO 22 would have the following form after being executed:
Function Byte 1 Byte 2 Byte 3
GTO 22 D6 16 16
If the three bytes are put end to end, the entire instruction may be viewed as:
[Diagram comes here.]
Thus the first four bits give the type of instruction (GTO), the next three bits give the location of the LBL within the register where it is stored, the next nine bits give the distance from the GTO to that register, the next bit tells whether the register is before or after the GTO and the last seven bits retain the name of the LBL. The name of the LBL must be retained in case program modifications invalidate the address retained in the first two bytes. Any addition or deletion of program steps sets all address bits in all GTO's and XEQ's to zero.
The local XEQ function is analogous except that the first four bits are hexadecimal E instead of D.
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I hope I didn't make any mistakes while retyping that!
X<>Y
-Ernie (6594)