Epson LQ-2550 Technical Manual page 93

2.3.1.4 Font/lndentity Module Installation and Removal
Figure 2-36 shows the reset circuit and Figure 2-40 shows the module installed/removed reset timing.
The font and indentity modules should not be installed or removed while
the ROUT signal must be set low to prevent a ROMA board circuit malfunction.
After reset, the main CPU starts execution for address 00001-1 and sends a ~ signal to the
The reset circuit in the MMU counts 32x= pulses and then generates a RDCLK pulse. When a module is
installed or removed, the exculsive OR value of CAR1 and CAR2 changes from the reset default value, and
the DISC signal is set low by the rising edge of the second pulse of the synchronized RDCLK signal.
Consequently, the THLD voltage begins decreasing. When the THLD voltage drops to V
goes high an then begins increasing. When it rises to VP, the ROUT signal goes high and the main and
sub CPUS restart from address OOOOH.
Also, Table 2-31 shows the relationship between the input at CAR1 and CAR2 of MMU (1 4A) and the
state of the mudule.
DISC
ROUT
RD CLK
Installed
Not installed
Removing
Mounting
1
1
1
1
1 2
A
CARATRIDGE IS
INSTALLED ~ REMOVED
Figure 2-40. Module Installed/Removed Reset Timing
Table 2-31. State of Module
Removing
Mounting
Removing
1
1 1
1
1
1 2
A CARTRIDGE REMOVED
L
2-46
the power is on. If this is done,
memory devices.
the DISC signal
N
ROUT
H -L
"
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