Heathkit H9 Manual page 24

P ase2 2
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oDD/EVEN PARITY (E)
This input (E) to the UART selects the type of parity
that is checked by the receiver and generated by the
transmitter if parity was selected as explained above.
A logic o on the E input (pin 36) will insert odd parity
immediately after the data bits. A logic 1 on this input
inserts even parity immediately after the data bits.
Since the Terminal does not use the parity bit, the E
input is not connected. If your special application
requires a parity bit, Pictorial 2-77 shows how to
select odd or even parity,
KEYBOARD PROGRAMMING
A jumper wire connection on the bottom of the
keyboard circuit board lets you select one of four
repe at r at es ; 3. 7-, 7.5 -, \5- , or 3 0- ch ar ac te r s pe r sec-
ond. This is the rate at which characters are written on
the screen when the REPT (repeat) key and a character
key are held down at the same time. Refer to the
"Repeat Rate" instructions in the "Readjustment"
section of this Manual if you want to change the
repeat rate.
TYPICAL TERMINAL/COMPUTER SYSTEMS
Parallel Input/Output Connections
The following parallel I/O connector chart describes
the signal on each pin ofthe parallel I/O connector on
the rear panel.
Odd/Even Parity
E V E N PA R I TY
O D D P A R Y
t/ 0 ct Rcut l
BO A RD
(ffiJ
oN lo o
o N 2o
o
oP o o
+ +
a o
o N l o o
o N 2o
o
oP o o
+ +
PICTORIAL 2.I7
PIN #
DATA DESCRIPTION
7
2
3
4
5
6
7
8
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
BiI T
Bit 8
Parallel
Output
o Positive true logic.
o High Level Output Voltage (Vo") : 2.7 min. @ -400
pA (High Level Output Current).
o LowLevel OutputVoltage (Y ot\ : 0.4 Vmax. @ amA
(Low Level Output Current).
o Standard 74L5175 latches.
I DAVo Take Data
o Output Data Available - Normally high. The Video
Terminal will hold this line low to indicate that there
is data available at the parallel output for the external
device.
r HighLevel OutputVoltage[Vr") : 2.7Y min. @ -400
p.A (High Level Output CurrentJ.
. Low Level Output Voltage [Vor) : 0.4 V max. @ a mA
(Low Level Output Current).
. Refer to the "Handshake Timing" section.
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