A
ll
and more about Sharp PC-1500
at
http://www.PC-1500.info
Refering
to
the block diagram, the CE-150
is
the printer (DGP!
301)
and t
he
CMT
(cassette tape
recorder
interface) which consists of three blocks, the CMT interface, printer interface and power
supply circuit.
• CMT interface
"!he CMT interface
is
the circuit
that
handl
es
data transfer betwe.en the
PC
· I
500
and the
CMT
and
consists
of
a si
mp
le driver ci
rc
uit (volt
age
level conversion circuit).
In addition, there
is
the C
MT
on/off
remote controlling circuit which
is
under the program
contro
l
of the
PC-I 500 and performs
sw
itching operation
via
the 1/0 port usiJig the
re
lay circuit.
•
Pr
inter i
nterf
ace
The
printer intefoee consists
of
character generator
ROM
(LH5367-01),l/0
port (LH58
0J),
motor
drive circuit, print solenoid drive circuit, and the pen color detect input
signal
circuit.
• Power supply block
A simple power stabilization circuit is provided
to
take ca
re
of
recharge to the built-in NiCd
batteries
from the
AC
Adaptor.
3.
CIRCUIT
DESCRIPTION
3·
1.
CMT
Interface circuit diagram
e
The
signal
CMT
OUT is sent from the
PC
-1
500
to
write data on the cassette tape and the capacit
or
coupled interface circuit
is
provided to
sh
ift the
vo
ltage level before supplying the
MIC
jack.
The
read signal is the input from the £ARPHONE jack and passed through the capacit
or
and two stages
of
gates
to
perform
vo
ltage
leve
l
sh
if
t and waveform shaping and delivered to the
PC
-I 500 as the
CM!T
IN signal.
Wi
th
respect to the
CMT
IN signal, the gate input
to
the first stage
of
the gate
is
forced to a
low
l
ev
el
by
means
of
the
PAO
signal as there is a possibility
of
supplying no
ise
to
the EARPHONE jack
as
input
data
to
the
PC
· I 500, except during the data read mode.
Do not sale this PDF
!!
!
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