Pset Instruction; Calz Instruction - Epson 6200A Core Cpu Manual

2 MEMORY AND OPERATIONS

2.1.6 PSET instruction

Jump or call instructions must follow PSET immediately in order for PSET to affect the destination address.
When a jump or call is not immediately preceded by PSET, the destination address is within the current
page.
Some examples using PSET are shown in Table 2.1.6.1.
Bank Page Stap
0 01H 10H PSET
0 01H 11H JP
• • •
• • •
0 01H 21H PSET
0 01H 22H NOP5
0 01H 23H JP
• • •
• • •
0 01H 55H SCF
0 01H 56H PSET
0 01H 57H JP
• • •
• • •
0 01H 60H RFC
0 01H 61H PSET
0 01H 62H JP
0 01H 63H JP
• • •
• • •

2.1.7 CALZ instruction

CALZ is a direct subroutine call instruction. It calls a subroutine, in page 0 of the current bank, from any
page without requiring the use of PSET.
If CALZ is executed immediately after PSET, the bank and page set by PSET is canceled. This allows direct
subroutine calls to page 0, minimizing repeated code and unnecessary use of PSET. See Figure 2.1.7.1.
6
Table 2.1.6.1 PSET examples
Instruction
13H
08H The program jumps to bank 1, page 3, step 8.
•
•
15H
The data set by PSET is canceled.
09H The program jumps to bank 0, page 1, step 9.
•
•
C flag is set.
14H
C, 07H The program jumps to bank 1, page 4, step 7 because C flag = 1.
•
•
C flag is reset.
05H
C, 08H No jump occurs because C flag = 0.
09H The data set by PSET is canceled, and the program jumps to bank 0, page 1, step 9.
•
•
Bank 0 Page 2
PSET 0AH
CALZ EEE
LD A,0
Fig. 2.1.7.1 The use of the CALZ instruction
Operation
Bank 0 Page 0
EEE....................
RET
Not effect
on destination
of CALZ
EPSON
S1C6200/6200A CORE CPU MANUAL