> doc Parallel device driver within RISC OS 2.50 ------------------------------------------ This module provides the parallel device support within RISC OS 2.50. The module is a client of DeviceFS and can be access via that system. It will setup PrinterType$1 to point at its DeviceFS object, ie: PrinterType$1 => devices:$.Parallel The module also supports a single SWI: Parallel_HardwareAddress ------------------------ in: - out: r0 -> base address of parallel 82C710 in IOEB space / =0 if no 710 present. This call is provided to allow external authors to drive the 82C710 for themself, the SWI is provided to simply return the base address and does not give any other support for the device. If you intend to drive the hardware directly then you should really perform the following: lock =OPENOUT("parallel:") .... play around with hardware.... CLOSE#lock This stops the device driver playing around with the values that you have setup and therefore stopping any confusion.