Heathkit H9 - Typical System; Typical Computer Systems; Typical I;O Connections

-
Pagezs
@
PIN
#
DATA DESCRIPTION
17
72
13
74
15
16
77
18
B
B
B
B
B
B
B
B
t1
t2
t3
t4
t5
t6
t7
t8
Parallel
Input
o
Positive true logic.
o
High Level Input Voltage
(Vr")
:
2
V min.
o
Low Level Input Voltage
(Vrr)
:
0.8
V
max.
.
Low
Level Input
Current
(Irr)
:
-2OO
p"A
max.
@
o.4
vL.
o
Standard 74L5244 input
buffer.
19 mAv; Data Taken
.
Reset
Output Data Available
-
Normally high.
o
The external device will
pull
this line low
to indicate
to the
Terminal
that it has
received
the data.
The
Terminal will not
send new
data until n-Dffz, has returned high.
o
High Level Input Voltage
(Vnt)
:
2
V
min.
o
Low Level Input Voltage
(Vrr)
:
0.8
V max.
.
Low Level Input
Current
(Irr)
:
2.8 mA
max.
.
Refer to
the
"Handshake
Timing"
section.
20 DAV;
Data
Sent
.
Input Data Available - Normall5r
high. The
external device will
pull
this line
low to
indicate
that there
is
data ready to be
inputted to the
parallel
input.
o
High Level Input
Voltage
(Vrrr)
:
2 V min.
o
Low Level Input Voltage
[Vrr,)
:
0.8 V max.
o
Low
Level
Input
Current
(Irr)
:
1.8
mA max.
o
Refer
to the "Handshake
Timing"
section.
27
m-AV,
Data Received
.
Reset
Input
Data
Available - Normally high. The
Terminal sends a negative-going
pluse
(:
25 p,S
wide)
on
this line to indicate to the external device
that the Terminal has received and is finished with
the data.
o
High Level
Output
Voltage
(Vo")
:
2.7 V min.
@
-+oo pA
(Ior).
.
Low Level
Output
Voltage
(Vor)
:
0.4 V max.
@
4 mA
(Ior).
.
Refer
to the "Handshake Timing"
section.
22
23
24
Ground