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Status
STATUS TRANSFER PRIORITY
When handshaking is in effect and more than one status request is received, status data
transfers are constructed and sent in the order of the block transfer priorities shown below.
Only one status transfer occurs for each complete handshake, although more than one may be
pending.
PRIORITY OF BLOCK TRANSFERS
highest
lowest
Primary status
(Ec
A)
Secondary status
(Ec "')
Device status
(Ec
&p<n>A)
Cursor sense
(Ec '
or Ec a)
Transmit user keys (fl-fB) type
Display transfer ( . key or
Ec d)
Command completion status (S, F, or U returned)
Terminal ID and capabilities
(Ec
*5
A
)
If more than one status request of the same type is received, only the most recently received
is acknowledged and sent when the handshaking is completed.
TERMINAL IDENTIFICATION
You request the terminal ID status by issuing the following escape sequence:
Ec
*5
A
or
Ec
*S
1
A
The terminal responds by sending back the following five-character string:
26.20A
INTERPRETING STATUS
For status requests, the terminal returns an escape sequence followed by a string of bytes.
The status information is contained in the lower bits of each byte. The upper bits are set so
that the byte translates into an ASCII printing character (characters with ASCII decimal
values from 32 to 126). The format for primary, secondary, terminal capabilities, and device
status requests is shown in figure 8-1, 8-3, 8-5 and 8-10, respectively. Notice that the upper four
bits of each byte in figures 8-1 and 8-3 are set to
"0011",
which limits the ASCII decimal values
to a minimum value of 48 (for these requests), well within the range of ASCII printing charac-
ters. The format for terminal capabilities status bytes is similar.
8-3
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