HP 5501A Operating And Service Manual page 172

Table 4-75. 70762A Cornparator/70764B Fast Pulse Converter lnput/Output Format
A. DATA FORMAT OF 1074614 BINARY INTERFACE
1. The data output of the 10746A Binary Interface includes 28 bits of data plus 4 bits of status/deci-
ma1 point which come from both the 10762A Comparator and the 107646 Fast Pulse Converter.
Format can be either two 16-bit words or four 8-bit bytes. (jumper-selectable on the 10746A
Binary Interface).
a. Two 16-bit Word Format
This format outputs the position data in two 16-bit words in the following format
with the most-significant bits first.
Word 1
MSB
D3 D 2 D 1 C27 C26 C25 C24 C23 C22 C21 C20 C19 C18 C17 C16
Word 2
LSB
C 1 5
C14
C13
C12 C l l C 1 O
C 9
C~
C7 C 6
C 5
C4
C3 C2
C1
C~
Where D
--
Decimal Point/Status
C
--
Counter Data
If D 3 D, Dl Do = 1111, this indicates either a measurement error or the fact that the counter
and comparator are within the +4-bit tolerance. Bits C , , C , , C , , C2, will determine which
condition exists. When bits C , , C , , C , , C , , = 1 1 1 1 then the Counter and Comparator are
within the +4-bit tolerance. If C , , C , , C , , C , ,
+
1111, then these bits will be a code indicat-
ing the following measurement errors:
If C , ,
=
0,
a VOL error exists.
If C2,
=
0,
an overflow error exists.
If C , ,
=
0, a reference error exists.
If CZ4 = 0, a measurement error exists.
If D3 D, Dl Do
1 1 1 1 then these bits will indicate a decimal point location (Resolution
Extension) and bits C , , C , , C , , C , , will then be data.
b. Four &bit Byte Format
In this case the data will be inputted in a format of four 8-bit bytes with the first word
being the decimal point/status and the 4 most-significant data bits.
Word 1
MSB
D3 D2 C27 C26
C 2 5
C24
Word 2
C23 C22 C Z I C20 Cis Cia C17 Ci6
Word 3
C15
C14
C13 C12 C1'l
C l ~
C9
C8
Word 4
LSBC, C6 C, C , C3 C, C, Co
The same rules for the decimal point status bits apply here a s for the two 16-bit word format.
2. Data Input to Comparator Card
When it is desired to input the Destination and Tolerance data to the 10762A Comparator
Card, the data can be inputted in either the two 16-bit word or four 8-bit byte format.