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• REGISTERS
The LCD-UI has
six
4-bit registers and two I-bit registers
available to the programmer. l-bit registers are Carry F/F and
Status F/F. They are explained in the following paragraphs.
• Accumulator (A; A Register) and Carry F/F (C)
The result of ALU operation (4 bits) and the overflow of
the ALU are put into the accumulator and Carry F /F. Carry
F/F can be set, reset or tested. Combination of the accumulator
and Carry F/F can be right or left rotated. The accumulator is
the
main
register for ALU operation and Carry F/F is used to
store the overflow generated by ALU operation when the
calculation of two or more digits (4 bits/digit) is perfonned.
• 8 Register (8)
The result of ALU operation (4 bits) is put into this register.
B register is used as a sub-accumulator to stack the data tempo-
rarily and also used as a counter.
• X Register (X)
The result of ALU operation (4 bits) is put into this register.
X register
has
exchangeability for SPX register. X register
addresses the RAM me.
• SPX Register (SPX)
SPX register has exchangeability for X register.
SPX register is used to stack X register and expand the addres-
sing system of RAM in combination with X register.
• Y Register (Y)
The result of ALU operation (4 bits) is put into this register.
Y register has exchangeability for Spy register. Y register can
calculate itself simultaneously with transferring the data by bus
lines, which is usable for the calculation of two or more digits
(4 bits/digit).' Y register addresses the RAM digit and I-bit
discrete input/output common terminals.
• Spy Register (Spy)
Spy register has exchangeability for Y register. Spy register
is used to stack Y register and expand the addreSSing system of
RAM and I-bit discrete input/output common terminals in
combination with Y register.
• Stetul
F/F
(S)
Status F /F latches the result of logical or arithmetic opera-
tions (Not Zero, Overflow) and bit test operations. Status F/F
affects conditional instructions (LPU, BR and CAL). These
instructions are executed only when Status F /F is "I". If it
is "0", these instructions are skipped and Status F /F becomes
"I".
• INPUT/OUTPUT
• Discrete I/O (0 Terminal)
The discrete I/O is composed of l-bit latch and I/O pin.
Figure 7 shows the basic block diagram.
Reset signal bV reset function
Set instruction
On
Reset
in.truction----~
Figure 7 Discrete I/O Block Diagram
Reset Signals
by
Reset Function
Set Instruction
Reset instruction ----i---1
Set Instruction
---"'r-lI.-'
Reset Instruction ---If---I
Set Instruction
Owrflow outDUt
--6~
pulse from
preo
-
j~
scaler
a \!!I
(internal halt
"0"
IN
rei .... signal)
Test------!f---....:.:.,;.j
Internal halt
~
ignal
@
Helt signal
~
External
.~
Clock
for
prescaler
halt signal
"0"
Crystal oscilletor
for timer (32.768kHzl
Figure 8 Mask Option of 0
14
and 015 Terminals
152
Do -On
DIS/XI
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