PC1512 motherboard links
The PC1512 has no DIP switches to configure it, but there are eight option links on the motherboard. Some of them have jumper pins already present; others would need jumpers to be soldered on.
|LK1||LK2||LK3||Language for ROS messages|
|On||On||On||Diagnostic mode (English messages; most of the self-test is skipped)|
Documented in the Technical Manual, section 3.1.
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 plugged in!)
Documented in the Technical Manual, Appendix 7.
LK5: 32k ROM
This link is near the ROS ROMs; its use is not documented in the PC1512 technical manual. The schematic in the service manual suggests that when it is connected, the ROM is treated as 32k (2x16k) rather than the usual 16k (2x8k). It connects the A14 line on the ROM chips to the address bus.
LK6,7: Builtin graphics adaptor fonts
The links affect the font used by the built-in CGA.
|Off||Off||Normal: Codepage 437|
|On||On||Greek (on late models); otherwise Normal|
Documented in the Technical Manual, section 220.127.116.11.
LK8: Ready line
This link is near the floppy controller; it is not documented in the PC1512 technical manual. The schematic in the service manual shows that, if connected, it links the RDY pin of the floppy controller to the READY signal from the floppy drives. If it is not connected, the RDY pin is pulled high.
John Elliott 22 August 2003