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FUNCTIONAL DESCRIPTION
The MPU-A board is the processor board for the IMSAI 8080
Microcomputer System.
processor chip.
been chosen to be 100% compatible with the MITS Altair M8800 .
Microcomputer system so that all boards are 100% interchange
able between the Altair system and the IMSAI 8080 system.
Every effort has been made to keep the design simple and
straight-forward to maximize reliability and ease of main
tenance.
MSI and LSI are used where appropriate, and dis
crete components are held to a minimum for greater circuit
reliability and ease of assembly.
The 8224 clock driver chip and an 18 Megahertz crystal are
used to generate the 2-phase, 2 Mehagertz non-overlapping
clock for the 8080A.
status signals and two 8216 tri-state bi-directional bus
drivers are used to interface the 8080A with the IMSAI 8080
input and output data buses.
and control lines axe driven by tri-state bus drivers.
Unregulated +16, -16, +8 volts, and ground must be supplied
to the bus.
On-board regulation is used to arrive at the
power supply levels needed to run the chips.
circuit power regulators with overload protection are used.
The board is supplied with ample bypass filtering using both
disc ceramic and tantalum capacitors.
The board connector is a 100 pin edge connector on .125
inch centers 50 pins on each side.
by 10 inches, using 2 sided glass reinforced epoxy laminate,
with plated feed-through holes to eliminate the need for any
circuit jumpers.
nickel for reliable contact and long life.
cuitry is tin-lead plated for better appearance and more
reliable solder connections.
Power-on reset is included on this board along with pull
up resistors for all inputs required so that with the front
panel removed from the INSAI 8080 machine, the power-on reset
will start the program at position 0 out of a ROM.
necessary conditions are met so that the system will run
without the front panel attached, for use in dedicated con
troller applications where no operator-processor interaction
is desires.
MPU-A
It is designed using the 8080 micro
The bus arrangement and board connector has
A n 8212 is used as a latch for the
All other address, status,
The contact fingers are gold-plated over
MPÜ-A
Functional Description
Revision 1
Integrated
Dimensions are 5 inches
All other cir
All other
5 - 1
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