RISC OS Hardware Modifications

RiscPC video quality mod

Later versions of the RiscPC motherboards feature extra filtering on the video output signal to meet EMC requirements. Unfortunately this was implemented in a very cost sensitive way (i.e. mediocre quality), so much of the useful content of the video signal is lost in the process of being filtered. The video quality is affected by the vastly reduced bandwidth of the output, which results in the display looking fuzzy and blurred in screen modes demanding a medium to high pixel clock rate.

Hence there is a way to restore the original sharp picture quality by James Miller. Please note that only those those with sufficient skill should untertake this modification!

RiscPC MCLK timing adjustment

Around halfway down the page in IFEL's February-March 1999 newsletter in a section titled "VRAM and SIMM problems" are details of both the StrongARM card resistor modification and the infamous C32 capacitor removal. These are intended only as a last resort to fix problems that have been identified as being due to hardware timing issues.

Elsewhere the newsletter has useful information regarding the suitability of various SIMMs and VRAM parts for upgrading RiscPCs.