Apple II Technical Notes _____________________________________________________________________________ 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. _____________________________________________________________________________ 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 _____________________________________________________________________________ o Inside AppleTalk, Second Edition o AppleShare Programmer's Guide for the Apple II Family