Philips pm2521 - 2.1.6. Resistance measurements

17
1.3.5. Control section (Refer
to Fig.
18.)
1.3.5.
1.
Microprocessor
8035
The integrated
circuit
microprocessor
8035,
one
of
the
MCS-48
family
of
single-chip
microcomputers
forms the
basis of the
control section
of the PIVI2521
automatic
multimeter.
The 8035 is
the equivalent
of the
8048
except
that it has
no internal
program memory.
However, it
uses two
externally-located
read-only
memories
(2kx8-bit EPROM's)
with
address/data
decoding
facilities
for program
instruction
storage.
In addition
to
the
true
bidirectional
8-line databus,
the 8035 has
two
quasi-bidirectional
8-bit
data ports for
extra address
lines and
communication
with the
external
circuits
in the
PM2521
.
Data
written to these
ports
remains unchanged
until rewritten.
Each line
is able
to serve
as input
or output, or
both, even though
outputs
are statically
latched.
The internal
data memory
is
a random-access
store of
64x8-bits,
indirectly
addressable
through
the RAM
pointer register.
Fig.
15. Basic functional
blocks of 8035pP.
ST3369
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