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OSBYTE &06 (6) - Set printer ignore character

On entry, A=&06, X=new printer ignore character

On exit, X=previous printer ignore character


On the A, B, B+ and Electron, OSWRCH filters the ignore character out of the printer stream. This is usually used to stop a printer feeding two lines when the BBC Micro prints a single newline sequence. Such a printer may respond to both line feeds and carriage returns by advancing the paper, and the default setting, X=&0A (10), means that line feeds are not sent to the printer.

Alternatively by setting a serial printer with OSBYTE &05 and using the printer stream instead of the serial port for output (with OSBYTE &03), the filter can change the newline sequence sent to a terminal on the serial port or eliminate any undesired character.

When X=0, NUL characters are filtered from the output; while this does not matter for text, it disrupts printer escape sequences and graphics printing unless VDU 1 is used.

Characters printed with VDU 1 are never ignored and always reach the printer.

On the Master, ignore character filtering is optional; the command *CONFIGURE IGNORE or *CONFIGURE NOIGNORE turns filtering on or off on the next hard reset. See also OSBYTE &B6.

-- beardo 20:47, 19 September 2007 (BST)