GMS34004 Datasheet, PDF (39/105 Pages) Hynix Semiconductor – 4-BIT SINGLE CHIP MICROCOMPUTERS

Chapter 3. Instruction
(20) SM
Naming :
Status :
Format :
Function :
<Comment>
Subtract Accumulator to Memory and Status 1 Not Borrow
Carry to status
¥°
A ¡ç M(X,Y) - A
ST ¡ç 1(when A ¡Â M(X,Y))
ST ¡ç 0(when A > M(X,Y))
Data of the accumulator is, through a 2`s complemental
addition, subtracted from the memory word addressed by the
Y-register. Results are stored in the accumulator. If data of
the accumulator is less than or equal to the memory word, the
status is set to indicate that a borrow is not caused.
If more than the memory word, a borrow occurs to reset the
status to ¡È0¡È.
(21) IM
Naming :
Increment Memory and Status 1 on Carry
Status :
Format :
Function :
Carry to status
¥°
A ¡ç M(X,Y) + 1
ST ¡ç 1(when M(X,Y) ¡Ã 15)
ST ¡ç 0(when M(X,Y) < 15)
<Comment> Data of the memory addressed by the X and Y-register is
fetched. Adding 1 to this word, results are stored in the
accumulator. Carry data as results is transferred to the status.
When the total is more than 15, the status is set. The memory
is left unchanged.
(22) DM
Naming :
Status :
Format :
Function :
<Comment>
Decrement Memory and Status 1 on Not Borrow
Carry to status
¥°
A ¡ç M(X,Y) - 1
ST ¡ç 1(when M(X,Y) ¡Ã1)
ST ¡ç 0 (when M(X,Y) = 0)
Data of the memory addressed by the X and Y-register is
fetched, and one is subtracted from this word (addition of Fh)>
Results are stored in the accumulator. Carry data as results is
transferred to the status. If the data is more than or equal to
one, the status is set to indicate that no borrow is caused. The
memory is left unchanged.
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