Printers - Overview

Printers are any ALIASed devices starting with either an 'L' or a 'P'. The configuration of a printer in the configuration file can be fairly complex. However, a reasonably simple printer may be configured easily.

Using the following type of printer alias may result in an !ERROR=12 under some versions of MS-DOS and Windows NT:

alias LP /dev/lpt1 "my printer" CR...

To correct this error, change the alias line to reference just the lpt port, instead of dev/lpt. For example:

alias LP lpt1 "my printer" CR...

Previous to Visual PRO/5 1.03, the OS determined the default maximum number of columns to be printed. In subsequent versions, the default maximum number of columns is set to 80.

Parallel Mode

The default state of the printer device on PRO/5 is a line buffered printer (this is called PARALLEL MODE). All text sent to the printer is buffered until a form control command is sent. This causes the printer driver to 'flush' the buffer to the printer and perform the form control operation. This buffering allows the user to perform random positioning on the printer line even when the printer itself may not allow this control.

The position within the print line is controlled with the @ mnemonic. The @ mnemonic accepts one argument: @(10) would place the print position to the eleventh column in the print buffer. The first position is considered zero. Movement in the buffer using the @ mnemonic does not modify intervening characters in any way. An attempt to position past the end of the buffer will normally result in an !ERROR=1 (end of record). For options that control behavior at the end of the line, see PRO/5 Printers in the Installation and Configuration Guide. The length of the buffer is determined by the SPCOLS, CPCOLS values in the configuration entry modes and the current 'SP' or 'CP' mode. If not defined in the configuration entry modes, it defaults to 80 bytes.

While the printer is in parallel mode the driver will accept all of the slew and form control mnemonics.

Serial Mode

The line buffering may be disabled and re-enabled through the printer mode control mnemonics. These mnemonics are 'MP' (parallel mode) and 'MS' (serial mode). While the printer is in serial mode, the line buffer and the slew commands are disabled (see Print Slewing).