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PC1640 DIP switches

The PC1640 has 10 DIP switches, which control its internal graphics adaptor.

(See also the technical manual, section 1.22.)

SW1-5: IGA hardware emulation and initial graphics mode

Valid combinations are:

SW1 SW2 SW3 SW4 SW5 Hardware mode
Off Off On Off Off EGA with mono monitor (DISPLAY MDMONO)
On On On Off Off EGA with EGA monitor, 200 lines (DISPLAY ECD200)
Off On On Off Off EGA with EGA monitor, 350 lines (DISPLAY ECD350)
Off Off Off On On EGA with CGA monitor, 80 column (DISPLAY CDCOLOR)
On Off Off On Off EGA with CGA monitor, 40 column
Off On Off On Off Secondary EGA, mono monitor
Off Off On On Off Secondary EGA, EGA monitor, 350 lines
On Off On On Off Secondary EGA, EGA monitor, 200 lines
Off On On On Off Secondary EGA, CGA monitor
Off Off On Off On MDA (DISPLAY MDTEXT)
Off Off Off On On CGA 80 column (DISPLAY CDMONO)
On Off Off On On CGA 40 column
Any On Off On On Secondary MDA
Any On On On On Secondary CGA

Notes:

SW6, SW7: Select IGA font

If SW9 is turned on, then SW6-7 select the font used by the IGA. If it is turned off, then the English font is used.

SW6 SW7 Font variation
Off Off Danish
On Off Portugese
On Off Greek
On On English

SW8: Monitor type

This switch should be turned on for an EGA monitor, off for an MDA or CGA monitor.

SW9: Enable 32k of EGA ROM

A genuine EGA has a 16k ROM. Turn this switch off to make the PC1640's internal graphics adaptor limit itself to a 16k ROM for strict EGA compatibility, or on to use the full 32k ROM. If SW9 is turned off, then the font selection switches SW6 and SW7 are ignored.

SW10: Disable internal graphics adaptor

If this switch is turned on, the internal graphics adaptor is disabled. With the IGA disabled, switches 1-5 and 8-9 are ignored, and switches 6-7 specify the type of the add-on video adaptor:

SW6 SW7 Video mode
Off Off Add-on EGA or VGA
On Off Add-on CGA, 40 columns
Off On Add-on CGA, 80 columns
On On Add-on MDA

John Elliott 12 April 2003