Specifications
REV.-B
Table 2-5. Functions of the Main
IC
and Circuits (Cont.)
IC
or Circuit
Location
Functions
STK-6022B
2A
This is a single chip that houses drive circuits for the printhead,
MOTOR,CR
and MOTOR, PF of the PRINTER MECHANISM. The chip also includes the
various sensor input circuits for the PRINTER MECHANISM.
PROM
5E
PROM contains the program that runs the CPU.
RAM
6E
Holds the CPU working area and the various buffers. (1 E is not used for
IE
an 80-column device and is not installed.)
MROM
3E
Holds the character design (also called the character generator).
(Mask ROM)
4E
EEPROM
4C
EEPROM
is an electronically writable and erasable ROM used to hold such
information as the TOF position.
Vref Circuit —
This is a circuit for generating the reference voltage used in the A/D
convertor within the CPU.
2.3.2 Reset Circuit
Figure 2-19 shows the reset circuit in block diagram form. The reset circuit issues the RESET signal.
Each part of the control circuits is initialized when this
RESETsignai is received. The conditions when
the RESET signal is output are described below.
When turning on the power supply
Immediately after the power has been turned on,
STK-6022B
(2A) outputs the VCCON pulse.
E05A50
(4D) receives this pulse and then outputs the DISC pulse. The electrical charge in the condenser within
the
STK-6022B
is then discharged. After this, STK-6022”B outputs the THLD signal, and
E05A50
then
outputs the RESET signal. After a certain time has elapsed, the charge in the condenser in the
STK-6022B
builds up again. The THLD signal is canceled and then the RESET signal is canceled.
Resets performed by the CPU itself (CPU self-reset)
The CPU outputs the RESET signal if there is a RESET request for
E05A50
and if
E05A50
has output
the DISC pulse.
+5
v.
STK-6022B
Line
E05A50
(2A)
4
(4D)
-----------
-----------
75
107
vmm
mm
73 106 —
THLD THLD
—
72
DISC
’
05
m
WsET
Figure 2-19. Reset Circuit Block Diagram
2-15