HP PCL/PJL reference - Printer Job Language Technical Reference Manual

EN Product-Specific Feature Support A-49

Backward-Compatibility Mode

If the printer detects PCL data immediately after a job boundary, it

enters a backward-compatibility mode that responds like an HP

LaserJet III printer. This lasts until the next job boundary is detected.

For backward- compatibility mode to occur, the PERSONALITY

variable must be set to AUTO or PCL, and the job must contain only

PCL data—if any PJL commands are received during the job, the

printer does not enter backward-compatibility mode.

There are two differences between backward-compatibility mode and

normal operating mode. In backward-compatibility mode, when a PCL

printer language reset (<ESC>E) is executed, instead of causing the

PJL Current Environment variables to be loaded into the Modified

Print Environment, the User Default Environment settings (control

panel values) are loaded. This is the same way the LaserJet III printer

works.

Note Because HP LaserJet 4L, 5L, 6L, and 1100 series printers do not

support job boundaries (JOB/EOJ), they always load the PJL Current

Environment variables into the Modified Print Environment after

receiving an <ESC>E reset.

Also, when a backward-compatible job ends with a partial page (one

not terminated with a form feed or PCL printer language reset) and

the job times out, the job does not immediately end, printing the

partial page. Instead, the printer waits to see if the next job sent

consists of more PCL data (from the same I/O port), which it then

appends to the partial page already in the printer. (This works the

same way as the HP LaserJet III printer, which does not have a job

timeout.) If PJL data is received instead, the partial page is printed

before the new PJL job is executed.

Printers that support the backward-compatibility mode:

HP LaserJet 4, 4M, 4 Plus, 4M Plus, 4V, 4MV, 4Si, 4SiMx, 4L, 4ML,

4P, 4MP, 4PJ, 4LJ Pro, 4LC, 4000 series, 5, 5M, 5L, 5P, 5MP, 6L, 6P,

6MP, 5Si, 5SiMx, 5Si Mopier, HP Color LaserJet, HP Color LaserJet

5, 5M, 1100 series, 2100 series, 4500 series, 5000 series, 8000

series, 8100 series, 8500 series