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PC2086 DIP switches

The PC2086 has 8 DIP switches accessible from the back of the case, which control various aspects of the builtin Paradise VGA display hardware.

SW1,2: Initial video mode

These switches only take effect when the built-in Paradise chipset is disabled and an add-on graphics card is plugged into an ISA socket (see SW4 below).

SW1 SW2 Add-on card type
Off Off EGA or VGA
Off On CGA, 40 columns
On Off CGA, 80 columns
On On MDA, 80 columns

SW3: Disable built-in serial port

Turn this switch on to disable the built-in serial port, in case you have a modem fitted that also wants to be COM1:

SW4: Disable onboard VGA

If this switch is turned on, the built-in VGA will be disabled and another video card must be used. Switches 1 and 2 set the type of the other card.

SW5: Multisync monitor

If this switch is turned on, the video timings will be altered to provide a better picture on a multisync monitor.

SW6: Auto colour/mono switching

If the switch is on, the video card will automatically switch between colour and monochrome modes depending on what the current program requires. If it is off, then monochrome/colour switching must be done manually with the DISPLAY command.

This switch must be turned off if you fit an MDA or Hercules card for a dual-head system.

SW7,8: Reserved

It is likely that these two switches are not used. Nearly every Paradise VGA chipset I've seen has four option switches but only uses the first two, so it's likely that these switches are the other two.

If you can't get the PC to display using its built-in VGA, a safe setting to use is to have all the switches off (up) except for switch 6 on (down).

John Elliott 3 July 2004