Parallel port

Ned Konz ned at
Sun Apr 7 19:00:31 UTC 2002

On Sunday 07 April 2002 11:30 am, ducasse wrote:
> Apparently they were under Windows and want to switch to linux.

Under Linux, the best way (probably) is to use /dev/parport* (the ppdev 

The easiest way is to enable access to the IO ports and do byte read/write. 
You enable access using ioperm or iopl, which can only be used by root. If 
this doesn't bother you, you can make a set uid launcher that does an ioperm 
call to enable access to the parallel port hardware and then exec's Squeak. 
If you do this, you have to make sure that neither the lp nor ppdev drivers 
are loaded (you could dynamically unload them if they were modules). ioperm 
is inherited on exec.

> What the guy told me is that they have on bit per motors so they can have
> up to 16 motors.

Since when are there 16 output bits per parallel port? Are they using latches 
or something? At best, you've got 8 data bits and a few output control bits 
(strobe, autoLF, init, select) from the parallel port hardware.

Ned Konz
currently: Stanwood, WA
email:     ned at

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