HP 9800 SERIES - Read Loopback Record

A-14 HP 9895A Disc Memory Command Set
Read Loopback Record
Type:
Purpose:
Description:
HP-IB Sequence:
ATN
rlO~DDRSI
Primary
Talk
Status:
Parallel
Poll:
ATN
I Pllllll0 I
Secondary
Sense.
The 9895A sends up to
256 bytes (see Write Loopback
Record) from its internal data buffer over the
HP-IB. This is
used by diagnostics to test the
HP-IB data path.
Upon accepting the loopback secondary, the 9895A
sends
the bytes stored in its internal buffer. The most significant
byte of the first word is transferred first. The 256th byte
will
be tagged with an EOI and the transfer terminated. If fewer
than
256 bytes are requested, the device will realize that
the transfer is complete when:
1. The 9895A has been untalked,
2. It accepts another byte from the
HP-IB.
P
P
D
No errors.
Sl -0
- 1 to 256 Bytes -+
Stat 2 - Unchanged
DSJ - Unchanged
EOI
ATN
P
~ I PIOlllllI
Untalk
If less than the specified number of bytes is accepted by the
HP-IB controller, the parallel poll response will be re-
enabled by the Untalk command.