RCH
INSTALLATION AND MAINTENANCE MANUAL model TOUCH ME
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9.6 ADDRESS BUS AND DATE BUS CIRCUITS
The CPU (X1) uses a bus composed of a 20 bit (A0-A19) ADDRESS BUS and an 8 bit
(D0-D7) DATE BUS for transferring date with the SRAM, and a 75hc377 (X6) interface to
generate the scanning signal of the keyboard lines, through the decoder (X7) 4051.
Furthermore, the 75hc377 (X6) interface pilots the drivers (X9, X10) of the printer’s paper
advancement motor.
All the components connected to the BUS are activated by the microprocessor, signals
CS0 and CS1 for the SRAM and the interface of the date bus 75hc377 (X6).