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PC200 motherboard links

The Sinclair PC200 motherboard has 7 option links. Some of them have jumper pins already present; others would need the jumpers soldered on to be used.

LK1-LK3: Language

LK1 LK2 LK3 Language for BIOS messages
Off Off Off English
Off Off On German
Off On Off French
Off On On Spanish
On Off Off Danish
On Off On Swedish
On On Off Italian
On On On Diagnostic mode (English messages; most of the power on self test is skipped)

LK4: Memory size

This link has a jumper on three pins. If it is on the left-hand pair of pins, then the memory size is 512k. If it is on the right-hand pair, the memory size is 640k (the extra memory chips must actually be present on the motherboard!)

LK5: Unknown

According to the service manual, this link has three pins: Ground, +5 Volts, and the NDMACS line (which runs between the bus gate array and the DMA controller). There are three possible uses for this:

LK6,7: Builtin graphics adaptor fonts

Unlike the other links, these can be seen simply by opening the expansion bay cover; there is a hole in the motherboard shielding which exposes these links and a ROM chip which contains the fonts.

The links affect the built-in MDA and CGA fonts.

LK6 LK7 Font
Off Off Normal: Codepage 437
Off On Norwegian: Codepage 865
On Off Portugese: Codepage 860
On On Greek

John Elliott 14 June 2003