Permanent Block Mode; Handshake Priority - HP 262SA Reference Manual

Block Data Transfer
Status
NONE = GH
and Ec d: DCI = --G
Transmit NONE = H( G + BD)
function DCI
= --G( --B
+
--D ) = --(G+BD)
key: DC2 = --H( G + BD)
Modify NONE = --G + H
modes: DCI =0
DC2
= (--H)(G)
Notes: 1. Permanent Block mode (multipoint datacomm) is equivalent to
G=H=I.
2. Handshaking for modify modes (Line Modify and Modify All), for this
terminal, is different from previous 262X terminals.
Permanent Block Mode
When the terminal is configured for HP multipoint datacomm operation, it is in a mode
referred to as cCpermanent Block mode" and the effective settings of the
InhHndShk(G)
and
I nh DC2 (H)
straps are both cCYe
5",
regardless of their settings in the configuration menu. In
permanent Block mode, there is no handshaking for any data transfers.
Handshake Priority
When handshaking other than cCnone" is in effect, and during receive mode ofa half-duplex (e.g.
HP multipoint) datacomm configuration, more than one status request or other form of block
transfer may be pending while waiting on the completion of a handshake. In this situation,
there is a prioritization of the responses rather than a first-in, first-out arrangement. The
priority list is as follows:
DC2 for DCI/DC2/DCl handshake
Primary status
Secondary status
Device status
Cursor sense (absolute or relative)
User-defined function key of cCT" or cCN" type
-,1:1,
or send display (Ec d) Command completion status code (S, F, or U) Terminal ID,
terminal features, or graphics status
The priority list is implemented by an internal queue. Only one request response is sent for
each handshake completed. For device status, cursor sense, function key, and command
completion code status transfers, there may be more than one request before the handshaking
is done to allow the resulting transfer to take place.
9-5