Epson LX-HOO Technical Manual page 44

REV.-A
Pin Port
Number Assignment
25
26
27 MODE 1
28 RESET
29 MODE O
3 0 x 2
31 x l
32 Vss
AV
33
SS
34
36
37
38
39
4 0
41
42
VA
REF
4 3 A V
C C
4 4
Table 2-3. CPU Port Assignment (cent'd)
Signal Line
Name
—
I Non-maskable interrupt input.
at the trailing edge of this signal. This pin is invalid because it
is tied to ground.
I — Interrupt input. The interrupt routine is executed at the leading
edge of this signal. This pin is invalid because it is tied to
ground.
— External memory space setting port. MODES 1 and O (pin 29)
are both pulled up to HIGH so that an external memory of 64K
bytes (addresses O through FFFFH) can be used.
RESET Reset terminal. When this signal is LOW, the printer is reset,
I
and ports A through C and D are set to be high impedance
input ports, and port F is set to be an address output (start
address OH).
I — Refer to pin 27, MODE 1.
CPU external clock input. This printer is driven with a 14.74
I —
MHz clock. The operation codes are fetched at approximately
1.3 MHz, and memory read/write operations are performed at
approximately 1.6 MHz.
—
- Ground terminal.
—
Ground terminal for the A/D converter in the CPU.
Analog input port of the 8-bit A/D converter in the CPU. Reads
I the states of DIP SW2-1 through SW2-3.
Analog input port of the 8-bit A/D converter in the CPU. Reads
the state of DIP SW2-4. This signal line is connected to the
AUTO FEED XT signal line of the interface. When DIP SW2-4
is ON, the automatic paper feed function is valid. When the
DIP switch is OFF, this function is controlled by a signal from
the host computer (not fixed).
—
I Analog input port for the 8-bit A/D converter in the CPU.
Reads the SLCT IN signal from the interface. When the SLCT-
~ signal is HIGH, DC l/DC3 control from the host computer is
valid. When it is LOW, DC l/DC3 control is ignored, and the
printer is always selected as a device. (The signal can be tied
LOW using jumper J 1.)
I + 2 4 Analog input port for the 8-bit A/D converter in the CPU.
Monitors the +24 V voltage and controls the printhead drive
pulse width.
—
-
Not used.
—
-
Not used.
—
I Reference voltage input for the 8-bit A/D converter in the CPU.
—
I
Power supply input for the 8-bit A/D converter in the CPU.
o Memory read timing strobe signal. Connected to the RD strobe
terminal of the gate array and the output enable terminal of
the ROM and RAM.
Description
2-12
The interrupt routine is executed