The IEEE-488 Bus was one of many expansion slots at the rear of the Commodore PET computer. It was not much used, because exorbitant fees were charged to licence devices for it, compared to the PET's user and expansion ports.

it was originally developed and used on the LSI-11 computer, and, i am told by Gorgonzola, (Thanks!) that it is the Standardized form of the HP-IB bus.

IEEE-488 instrument interface bus pinout:

1
DIO1
Data Line 1
2
DIO2
Data Line 2
3
DIO3
Data Line 3
4
DIO4
Data line 4
5
EOI
End of message
6
DAV
Data valid
7
NRFD
Not Ready For Data
8
NDAC
Not Data ACcepted(?)
9
IFC
InterFace Clear
10
SRQ
(peripheral) Service ReQest
11
ATN
ATteNtion: data is command
12
SHIELD
no connection
13
DIO5
Data line 5
14
DIO6
Data line 6
15
DIO7
Data line 7
16
DIO8
Data line 8
17
REN
18-24
GND
GrouND

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