Epson PX-8 User Manual page 9

1.2.4 Display
The PX-8 uses a large LCD display of 80 columns x 8 lines, on a hinge which
can be folded down to protect the display when not in use.
Unlock the display by pressing the switch on its right toward the rear. When
the display pops up slightly, open it by hand.
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UNLOCK
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Fig. 1.6a
The view angle control on the front of the display makes it possible to obtain
the optimum contrast.
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Fig. 1.6b
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1.2.5 CPU and memory
The PX-8 has three central processor units. The main CPU is a Z80 compatible
microprocessor. This controls the programs which are run on the PX-8. A slave
CPU 6301 is used for display and Input/Output (I/O) control, i.e. communi-
cation with other devices such as printers, disk drives, the internal speaker, cas-
sette drives etc. The sub CPU 7508 controls interfacing with the keyboard and
the Analog/Digital (A/D) converter which allows signals from other devices
to be read as voltages and converted into numbers the PX-8 can understand.
The main CPU controls 64K bytes of RAM and 32K bytes of ROM. The slave
CPU has 6K bytes of RAM (used as video RAM) and 4K bytes of ROM.
All RAM is backed up by built-in batteries so that the contents can be retained
when the power switch is turned off.
1.2.6 Microcassette tape deck
The PX-8 is equipped with a microcassette tape deck which can be used for
saving data and program files sequentially. The micro cassette tape deck is con-
trolled manually or by software.
MICROCASSETTE
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Fig. 1.7
The maximum number of files which can be stored in a microcassette is 12.
This restriction is due to the size of the directory on the cassette tape.
1-9