Heathkit H9 Manual page 23

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Word Length
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PICTORIAL 2.I5
BAUD RATE
Pictorial 2-14 shows the jumper wire configuration
for each ofthe five preset baud rates (600 to 9600). The
baud rate that you select appears on the Baud Rate
switch, SWz, on the back panel on the Terminal. This
lets you select one of two baud rates, 300 baud or the
rate that you programmed on the I/O circuit board.
NOTE: For baud rates greater than 600, refer to Detail
2-14A and move the green harness wire on switch
SW2 lug 3 to lug 2. Be sure to solder this connection.
woRD LENGTH (N1, N2)
The number of bits per word is determined by the N1
and Nz inputs (pins 37 and sa) to the UART. The
word length may be programmed for 5-, 6-, 7-, or
8-bits as shown below.
WORD LENGTH
N2 (pin 38) N1 (pin 37)
0
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PICTORIAL 2.16
The Terminal was initially wired for an 8-bit word.
You can, however, change the word length to suit
your particular application. To do this, remove the
wires from the holes labeled N1 and N2 on the I/O
circuit board. Then install wires to correspond to the
word length you desire. Pictorial 2-15 shows how to
connect jumper wires to select a 5-, 6-, 7-, or 8-bit
word. The four holes directly above the ground sym-
bol ($ connect to ground (logic 0). The four holes
directly above the plus symbol (*) connect to the
+s-volt supply (logic 1).
PARTTY (P)
The UART (IC612) can be programmed to either gen-
erate a parity bit for the serial output or to eliminate
the parity bit. A logic 1 on the P input (pin 35) to the
UART eliminates the parity bit from the transmitted
or received word. The stop bit (s) will immediately
follow the last data bit. A logic 0 on the P input causes
the UART to generate a parity bit.
The Terminal was initially wired for no parity. See
Pictorial 2-16 (Illustration Booklet, Page 5). This oc-
curs when a wire is connected between holes P and +
on the I/O circuit board. The parity bit is not used with
the H9 system. However, if your own special applica-
tion requires the parity bit, connect a wire between
hol es P a n d * .
8-B IT
WOR D
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