From: Flemming Steffensen

NORMAL JUMPERS:

J2    Function: Speaker (signal with 33R serial resistor)
      Position: Main board

J4    Function: Enable/disable onboard FDC
      Position: Main board

J5    Function: Enable/disable 384K above memory
      Position: Baby board

J6    Function: Floppy disk select  (PS/2:1.44MB or AT:1.2/1.44MB)
      Position: Daughterboard

J7    Function: Test connector

         note: Actualy it's a keyboard input:  1: NC
                                               2: NC
                                               3: KBDATA
                                               4: KBCLK
                                               5: PWRGOOD
                                               6: KEY
                                               7: +5V
                                               8: GND
      Position: Main board
      (please see this discussion about the above keyboard signals)


J13   Function: Battery connector for RCT
      Position: Main board

J14   Function: Select video startup mode
      Position: Daughterboard

SOLDER JUMPERS:

JS1A/JS1B   Function: DMA speed select
            Position: Main board

      JS1A closed, JS1B open : DMA works at sysclock/2 speed (Default)
      JS1A open, JS1B closed : DMA works at sysclock speed.

JS2A/JS2B   Function: RAS to CAS signal delay select
            Position: Daughterboard

      JS2A closed, JS2B open : Delay is 50ns (Default)
      JS2A open, JS2B closed : Delay is 70ns

JS4A/JS4B   Function: Onboard or External 16MHz oscillator select.
            Position: Daughterboard

      JS4A closed, JS4B open : Selects 16 MHz for FDC from main PCB (Default)
      JS4A open, JS4B closed : Selects 16MHz from U69 (Must be present!)

JS5A/JS5B   Function: BIOS EPROM type select
            Position: Daughterboard

      JS5A closed, JS5B open : 27128 EPROM (Default)
      JS5A open, JS5B closed : 27256 EPROM

JS7A/JS7B/JS7C/JS7D  Function: APU 80287 Speed select.
                     Position: Main board.

      JS7B/JS7D closed, JS7A/JS7C open : APU runs at sysclock speed (Default)
      JS7B/JS7D open, JS7A/JS7C closed : APU runs at sysclock/2 speed

JS8A/JS8B   Function: Real time clock bus timing select
            Position: Daughterboard

      JS8A closed, JS8B open : 80286 INTEL timing (Default)
      JS8A open, JS8B closed : 27256 MOTOROLA timing

JS9   Function: Real time clock standby mode.
      Position: Daughterboard

      JS9 closed : Standby mode (Default)  JS9 _must_ be closed.

JS10A/JS10B Function: Real time clock bus timing select.
            Position: Daughterboard

      JS10A closed, JS10B open : Select FE3000A  (Default)
      JS10A open, JS10B closed : Select FE3000   (8 MHz version)

JS11  Function: FDC write precompensation select
      Position: Daughterboard

      JS11 open   : Select 125ns (Default)
      JS11 closed : Select 187ns

JS12  Function: FE3000 / FE3000A select switch
      Position: Main board

      JS12 open   : Select FE3000A (10 MHz version) (Default)
      JS12 closed : Select FE3000