The Early Microcontroller :
80C39 is a CMOS Version of 8048 the
one that preceded 8031-8051. MCS48
is the set for that. Here are some
example projects for 80C39-8748-8749
microcontroller. MCS51 is the set
for 80C31 and 8051.
to Frequency Converter AD
Interface is the analog front
end of this instrument. Uses a LM331
VCO. The Signal conditioning too is
integrated in this circuit.
A complete two set point Process
Controller using 80C39. 8048 and its
mnemonic code set MCS-48, is
the first popular Microcontroller.
This had no Serial Port and limited
memory. This code was written by me,
and it works ok. Even though these
chips are obsolete, the interfacing
circuit and code can help learn some
and MCS48 based Process Controller
is the main circuit that has the LED
7 segment display for output and
push keys for input. The old form of
Human Machine Interface - HMI.
This was supposed to have Analog in
and Analog out. Some parts of the
circuit may be in the 80C51 page.
This has ramp-up and ramp-down
settings for the Increment and
Decrement buttons. This helps
setting setpoint quickly. There is
also debouncing for the pushbutton.
The MCS-48 microcontroller (µC)
series, Intel's first
microcontroller, was originally
released in 1976. Its first members
were 8048, 8035 and 8748. Initially
this family was produced using
NMOS-technology, in the early 1980s
it became available in
to Analog Converter with uC
Watchdog is the front end and
an external hardware watchdog
of an early kind. These are simple
but robust circuits and worked well
in noisy environments.
The Intel 8748 has on-chip clock
oscillator, 2× 8-bit timers, 27× I/O
ports, 64 bytes of RAM and 1 KB of
EPROM. A version with 2 KB EPROM and
128 bytes RAM was also available
under the 8749 number.
Learn more about current 8031 tools
here - Rigel
- Ebedded Controllers and Software
MCS-48 at Wikipedia
"Though the MCS-48 series was
eventually replaced by the very
popular MCS-51 series, even at
around year 2000 it remained quite
popular, due to its low cost, wide
availability, memory efficient
one-byte instruction set, and
mature development tools."
code here 80C39
Code for MCS48 (editable
spreadsheet online) or use pc80C39.zip.
The circuit for these are on this page
along with other circuits.
Single Components MCS-48 System
8-bit timer/event counter, Two
interrupts, Single 5-volt
supply, Three 8-bit
bi-directional I/O ports, Up to
256 bytes of data memory, Up to 4K of
This may be difficult to put together
now. But the code and hardware is near
compatible to 8051 uC. Now there are
may types of ADC and uC. Then there
Projects and AVR