Intel MCS-80/85 Computer Hardware User Manual


 
MCS·S5™
SPECIAL PERIPHERAL
COMPONENTS
The MCS-85 was designed
to
minimize the
amount
of
components
required
for
most
systems. Intel designed several new peripheral
components
that
combine memory,
110
and
timer functions
to
fulfill
this requirement. These
new peripheral devices directly interface
to
the
multiplexed
MCS-85
bus structure and provide
new levels in system integration for today's
designer.
101;;;----1
*---
..
,
AlE----1
AD---
....
ViiR---
..
'
RESET---",
TIMER IN
256 X 8
STATIC
RAM
TIMER
TIMER
OUT-------'
~Vee(+5V)
Vss
(OV)
*:
8155 =
CE,
8156 =
CE
8155/8156
RAM,
1/0
and Timer
256 bytes
RAM
Two 8·bit ports
One 6·bit port (programmable)
One 14·bit programmable interval
timer
Single + 5 Volt supply operation
40
pin DIP
plastic
or cerdip package
8355
ROM
and 1/0
2K bytes
ROM
~VCCI+5VI
vss IOVI
Two 8·bit
ports
(direction programmable)
Single + 5 Volt supply operation
40
pin DIP
plastic
or cerdip package
1·9
ClK
READY
ADo-7
A
s
-
lO
CE
101M
ALE
AD
iOW
RESET
lOR
2K x 8
EPROM
PROG/CE~
Voo
8755A EPROM and I/O
Socket compatible
with
8355
2K bytes EPROM
0
G
Vee (+5V)
L..---Vss
(OV)
Two 8·bit ports (direction programmable)
Single + 5 Volt supply read operation
U.V.
Erasable
40
pin DIP package
One
of
the most important advances made
with
the
MCS-85
is the socket-compatibility
of
the
8355 and 8755A components. This allows the
systems designer
to
develop and debug in
erasable
PROM and
then,
when
satisfied,
switch over
to
mask-programmed
ROM
8355
with
no performance
degradation
or
board
relayout. It also allows
quick
prototype produc-
tion for market impact
without
going
to
a com-
promise solution.
TIMER IN
TIMER OUT
1/0
PORTS
SYSTEM EXPANSION
1/0
PORTS
I/O
PORTS
Each
of
these peripheral
components
has
features that allow a small
to
medium system
to
be constructed without the addition
of
buf-
fers and decoders
to
maintain the lowest possi-
ble component count.