How do laserjets process Jobs?

[Redi2Learn]

Hello!

I know this may be an odd question...How do printers process jobs? Do they take one page at a time? Or do they take the entire job then print.

I was also wondering what the printers are are setup to do when they have multiple jobs coming from multiple places. For example getting multiple print jobs direct from a workstation, windows server, and Linux server.

Our printer is freezing up a bit and sometimes not accepting jobs, or taking a long time to process.

Thanks!!  :robothappy:

[dansdaduk · Accepted solution]

>> ... Do they take one page at a time? Or do they take the entire job then print ...

The printer will use some sort of flow-control mechanism to control how much data is received - once the 'input source' memory allocated to that function is full, the printer will signal that no more can be taken just yet.

The Page Description Language interpreter (typically PCL5, PCL XL, or PostScript) in the firmware starts interpreting the mix of data and control 'instructions' in the 'input source' memory, and (for each page that it recognises) constructs a raster image of that page in another reserved area of memory.

Once a 'page image' is ready, this is submitted to the print engine for printing, after which the page image memory is available to receive the image for the next page.

Note that for duplex prints the printer will usually construct two 'page images', and print the rear face first.

... and so on until the job is complete. 

in some cases, the print job (containing the mix of data and printer control instructions) may be only be few hundred bytes long, but may represent a number of pages (sometimes the whole print job).

With other jobs (typically those (like photographs) which contain lots of raster data), the print job data may be as large as the aggregate of the page images constructed by the interpeter.

>> ... I was also wondering what the printers are are setup to do when they have multiple jobs coming from multiple places. For example getting multiple print jobs direct from a workstation, windows server, and Linux server ...

Flow-control usually handles this quite seamlessly - most (although not all) printers can accept data simultaneously from multiple sources (e.g. USB and ethernet (port 9100 and/or or LPD, etc.)), provided that the memory reserved for input sources is large enough.

All of the above applies to how most (although perhaps not all0 LaserJet devices process print jobs.

Inkjet devices may use somewhat different mechanisms - I think that they tend to print 'blocks' (or 'bands'?) rather than 'pages'.

[Redi2Learn]

Wow...wonderful response. Thank you for taking the time to explain that to me.

Take Care!