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INSTRUCTION SET
SEL
MBO Select Memory Bank 0 (Not in 8021, 8022)
11110101011
PC
bit
11
is
set
to
zero on next JMP
or
CALL instruction.
All references to program memory addresses fall within
the range
0-2047.
(DBF)
....
0
Example:
Assume program counter contains 834 Hex.
SEL MBO
JMP $+20
SEL
MB1
Select Memory Bank 1
11111101011
;SELECT MEMORY BANK 0
;JUMP TO LOCATION
;48 HEX
(Not in 8021, 8022)
PC
bit
11
is set to one on next JMP or CALL instruction.
All references
to
program memory addresses fall
within the range 2048-4095.
(DBF)
....
1
SEL
RBO
Select
Register
Bank 0 (Not in 8021, 8022)
11100101011
PSW
bit 4
is
set to zero. References to working
registers
0-7 address data memory locations
0-7.
This is the recommended setting
for
normal program
execution.
(BS)
....
0
SEL
RB1
Select Register Bank 1 (Not in 8021, 8022)
11101101011
PSW
bit 4
is
set to one. References to working registers
0-7 address data memory locations 24-31. This
is
the
recommended setting
for
interrupt service routines,
since locations
0-7 are left intact. The setting
of
PSW
bit 4 in effect at the time
of
an
interrupt
is
restored by the
RETR
instruction when the interrupt
service routine is completed.
(BS)
....
1
Example: Assume
an
external interrupt has occurred, control
has passed
to
program memory location
3,
and
PSW
bit
4 was zero before the interrupt.
LOC3: JNI INIT ;JUMP TO ROUTINE 'INIT' IF
;INTERRUPT INPUT IS ZERO
Mnemonics copyright Intel Corporation 1976.
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