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Printers on the Classic TI-99/4A

Printer on the TI-99/4A  

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  1. 1. Do you have a printer hooked up to your TI-99/4A?

    • Yes
    • No
  2. 2. If yes, does it get much use?

    • Yes
    • No
    • N/A
  3. 3. If NO to question 1, do you plan to purchase one in the future?

    • Yes
    • No
    • Not sure

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Indeed @wierd_w controlling a plotter with HPGL is no problem from BASIC. 


My brother immediately saw the usefulness of our high school’s HP plotter, borrowed it, and wrote many routines in TI BASIC to plot conic sections. 

Those became components for assembling a parabolic dish and other experiments. 

It’s just text after all. 

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The point, was that the exact same routines (with a small PCL header to put the printer into HPGL2 mode, that an old pen plotter would simply ignore anyway) can control modern laser printers, since the HPGL language is almost 100% embedded in modern PCL.




(note, HP disabled the PG; command in HPGL2 mode on laser printers. This command tells an old pen plotter to kick out the page and load a new one. HP wants you to exit HPGL2 mode, then issue the appropriate PCL command.)




This is an eject plot command. It has been disabled in the LaserJets to allow mixing of HP-GL/2 and PCL commands on the same page.

The only way to eject a page is from PCL mode. The following commands will cause a conditional (if buffer holds data) page eject:


Printer Reset Command EcE

Page Size Command Ec&l#A

Paper Source Command Ec&l#H

Page Length Command Ec&l#P

Orientation Command Ec&l#O


The printer will also unconditionally eject the page if a form feed control code character is sent (Decimal value 012 in ASCII).

A form feed can also be invoked on the front panel of the printer if there is data in the buffer.


An old pen plotter will ignore the escape sequence command codes, and a PCL printer will ignore the PG; command.  This means that a general purpose handler that does both can issue the PG; command, then immediately issue the escape sequence command codes.  Regardless of what is connected, it will eject the page.



Edited by wierd_w
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