The 9-pin (Male) to 15-pin (Female) VGA adapter is designed to allow the connection of more modern monitors that are capable of using a 15-pin VGA connection. The earlier RISC OS Archimedes range of computers all have a 9-pin VGA video out connector and as such, this adapter is used in the cases where these computers need to connect to a modern monitor. The particular adapter that I use was available from
Using a standard VIDC chip, the A400 series and A3000 series are capable of resolutions up to 640x480 using 256 colours and with the use of a VIDC Enhancer circuit board can deliver standard modes up to 800x600 using 16 colours. If a VIDC Enhancer is used to overclock the VIDC chip, the machines are even capable of achieving a resolution of 1024x768 with 256 colours although to do this, the overclocking required would be regarded as extreme.
The adapter can be seen connecting to the 9-pin socket on the Acorn BBC A3000 and presenting a 15-pin socket to enable a standard 15-pin VGA cable to be connected as can be seen in the photo below.
Once connected, the Acorn BBC A3000 can be re-configured to use the higher resolutions available to (S)VGA monitors. The photo below shows my Acorn Archimedes A410/1 using an original AKF12 monitor next to my Acorn BBC A3000 using an IIyama 17" ProLite E430S LCD screen displaying a the RISC OS desktop at a resolution of 640x480 with 256 colours without a VIDC Enhancer fitted. Since I originally wrote this page, it appears that I was lucky to a certain extent in getting this working without a VIDC Enhancer as the A400/1 and A3000 series deliver VGA refresh rates that are 4.7% slower than the standard VGA refresh rates which the majority of monitors do not accept. In order to guarantee that all the screen modes an A400/1 or A3000 is capable of producing will display correctly on a (S)VGA monitor, a dual or Ultra VIDC Enhancer is required.
In addition to the 9-pin to 15-pin VGA adapter, the A410/1 requires a change to the motherboard in order to allow it to correctly output to a VGA monitor due to a bug that causes the green signal to be ignored when connected to a (S)VGA monitor.
provided courtesy of The IconBar