AutoVIDC - VIDC software control

Improving monitor compatibility and delivering higher screen resolutions
for the Acorn Archimedes range of computers.

AutoVIDC is a small piece of software that runs on RISC OS primarily to control a VIDC Enhancer although, that isn't its only job!

What is a VIDC Enhancer?

A VIDC Enhancer is a small piece of hardware that allow older Archimedes computers to deliver higher resolutions and improve support for modern monitors by providing a set of alternative clock speeds to the VIDC chip allowing it to run faster. By running the VIDC chip faster, you can enhance the video display capabilities of the Archimedes to match those of later models such as the Acorn A5000.

About AutoVIDC

Originally written by Andreas Barth in 1995 and now developed and maintained by Paul Vernon, AutoVIDC is unique amongst VIDC Enhancer software solutions in that it supports all known methods of setting the VIDC clock speed using either the Aux IO pins (for Atomwide and Beebug style VIDC Enhancers), the I²C bus (for Watford Electronics VIDC Enhancers) or the native Acorn VIDC Enhancer as built in to the later Archimedes A540, A5000, A4000, and A30x0 machines.

AutoVIDC replaces the bespoke software that was supplied with each different VIDC Enhancer (and usually targetted RISC OS 2). Through AutoVIDC every standard RISC OS screen mode that is provided by RISC OS from version 2.00 to version 3.11 is fully supported. Custom screen modes aren't forgotten either and they are supported through the creation of "Native" style screen modes using CustomVDU v1.71.

Standardised VIDC clock selection API

AutoVIDC also provides a full RISC OS SWI to deliver a standardised way of setting the VIDC clock speed for programmers regardless of the type of VIDC Enhancer fitted. This SWI is currently being used by the module LCDGameModes written by Steve Harrison which fixes many games that do not run correctly when an Archimedes is connected to a VGA or SVGA monitor.

Compatibility

AutoVIDC is designed to run on any Acorn Archimedes computer that has a VIDC1a chip fitted to it. As part of the initialisation process of AutoVIDC, the VIDC1a chip is detected and AutoVIDC gracefully exists if it is not found.

AutoVIDC has been tested on the following computers using a variety of versions of RISC OS:

• Archimedes A305 (RISC OS 3.10)
• Archimedes A310 (RISC OS 2 and 3.11)
• Archimedes A410/1 (RISC OS 3.11)
• Acorn BBC A3000 (RISC OS 3.11)
• Archimedes A540 (RISC OS 3.10)
• Acorn A5000 (RISC OS 3.11)
• Acorn A4000 (RISC OS 3.11)
• Acorn A3010 (RISC OS 3.10)
• Acorn A3010 (RISC OS 3.11)
• Acorn RISC PC 600 (RISC OS 4.02)
• Raspberry Pi (RISC OS 5.19)

AutoVIDC has been tested with the following VIDC Enhancers:

• Several VIDC Enhancers based on Andreas Barth's design
• Retro-kit Ultra VIDC Enhancer
• Watford Electronics "Standard" VIDC Enhancer

AutoVIDC should work (but has not been tested with) the following VIDC Enhancers:

• Atomwide VIDC Enhancer
• Beebug VIDC MODE Expander (find out about this Enhancer at Chris's Acorns)
• Watford Electronics "Super" VIDC Enhancer

The Atomwide and Beebug VIDC Enhancers are both Aux IO based designs so should work in the same way as other AuxIO based designs. The W.E. "Super" VIDC Enhancer is based on the same PCB as the "Standard" VIDC Enhancer and again should work in the same way as the "Standard" board does.

Known Incompatibilities

Where no VIDC Enhancer is fitted, AutoVIDC "assumes" an Aux IO based VIDC Enhancer is present. If other hardware is using the Aux IO pins, AutoVIDC could interfere with the correct operation of that hardware.

To my knowledge, there is only one piece of hardware that used the Aux IO pins which isn't a VIDC Enhancer. It is called IICAlarm and was created by Andreas Barth.