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Apple II
Technical Notes
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Developer Technical Support
AppleTalk
#9: The PAP Status Buffer
Written by: Jim Luther November 1990
This Technical Note shows the format of the status data returned into the
application-supplied status buffer by the PAPStatus and PAPOpen Printer Access
Protocol (PAP) AppleTalk commands. The status buffer format is shown for both
LaserWriter and ImageWriter (with the ImageWriter II/LQ LocalTalk Option card
installed) printers.
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The PAPStatus and PAPOpen AppleTalk commands must supply a pointer to a 260-byte
status buffer. When the PAPStatus or PAPOpen commands complete, the status
buffer contains the ATP data portion of a Status (TResp) packet. The first four
bytes of that data are unused, so the actual status data starts at offset $04 in
the status buffer.
The LaserWriter printer returns its status data in the form of a Pascal string.
That string is usually something suitable to display on the screen (e.g.,
"status: idle" or "job: Fred; document: My LaserWriter is on fire; status: busy;
source: AppleTalk"). In fact, the status text displayed in the Print Manager
LaserWriter dialog boxes is usually the statusString returned by PAPStatus or
PAPOpen. Figure 1 shows the contents of the status buffer returned by a
LaserWriter.
+-------------------+
$00 |_ _| Longword Unused
|_ unused _|
|_ _|
| |
+-------------------+
$04 |_ (string length) _|
|_ _|
|_ _|
. .
. status string . String The PAP status string
. . (Pascal string, ASCII,
|_ _| high-bit clear)
|_ _|
| |
$103 +-------------------+
Figure 1-PAP Status Buffer from a LaserWriter
The ImageWriter II/LQ LocalTalk Option card does not return a status string for
display. Instead, it returns a statusBits word where each bit within that word
has a specific meaning. Your application can interpret the statusBits word and
generate an appropriate message to display. Figure 2 shows the contents of the
status buffer returned by the ImageWriter II/LQ LocalTalk Option card and the
individual bit definitions of the statusBits word.
+------------------+
$00 |_ _| Longword Unused
|_ unused _|
|_ _|
| |
+------------------+
$04 |string data length| Byte Always = 2
+------------------+
$05 |_ statusBits _| Word Status bits returned by
| | LocalTalk ImageWriter
+------------------+ Option card (see following
$07 |_ _| definition)
|_ _|
|_ _|
. . 253 Bytes Unused
. .
. .
|_ _|
|_ _|
| |
$103 +------------------+
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|15|14|13|12|11|10| 9| 8| 7| 6| 5| 4| 3| 2| 1| 0|
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| |<-- Reserved --->| | | | | | | | |
1 = Printer is busy ----------+ |_________________| | | | | | | | |
| | | | | | | |
1 = Color ribbon installed ---------------------------+ | | | | | | |
1 = Sheet feeder installed ------------------------------+ | | | | | |
1 = Paper out error ----------------------------------------+ | | | | |
1 = Cover open error ------------------------------------------+ | | | |
1 = Printer off line ---------------------------------------------+ | | |
1 = Paper jam error -------------------------------------------------+ | |
1 = Printer fault ------------------------------------------------------+ |
1 = Printer active (head is moving) ---------------------------------------+
Figure 2-PAP Status Buffer from an ImageWriter II/LQ LocalTalk Option Card
There are two additional things to note when interpreting the statusBits word
returned by a ImageWriter II/LQ LocalTalk Option card:
o If a sheet feeder is installed (bit 6 = 1), running out of paper results
in a "Paper jam error" (bit 2 = 1) instead of a "Paper out error" (bit 5).
o The ImageWriter II/LQ LocalTalk Option card has been known to randomly
return all ones in the low byte (bits 0-7) of the statusBits word. When
this happens, the statusBits word is invalid and an application should
repeat the PAPStatus call to get valid information.
Further Reference
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o Inside AppleTalk, Second Edition
o AppleShare Programmer's Guide for the Apple II Family