AST-3G Plus                                         AST Part Number 202104-001

The AST-3G Plus is a video graphics adapter for use with the IBM PC/XT, IBM
PC/AT and 100% compatible machines.  The 3G Plus is an EGA (Enhanced Graphics
Adapter) board.  Through hardware reconfiguration, the 3G Plus can also act as
a standard color graphics adapter or as a monochrome display adapter.  The 3G
Plus can also emulate Hercules monochrome graphics.  Standard video memory
installed on the 3G Plus is 64K, upgradable to 256K.  There is an optional
parallel port available for this board.

The 3G Plus Adapter is compatible with the IBM EGA feature connector.  The
feature adapter allows for video input/output through the RCA video jacks at
the rear of the 3G Plus.  These video jacks are not enabled unless the feature
adapter is attached.


SWITCH SETTINGS

    If AST-3G Plus is the primary video adapter

          SW1 Switch
        Block Settings      3G Mode       2'nd Adapter     Monitor
         1   2   3   4     at Powerup         Mode          Type
        --- --- --- ---   ------------   --------------  ------------
        OFF  ON  ON OFF     EGA 80x25       MDA 80x25     EGA
         ON  ON  ON OFF     CGA 80x25       MDA 80x25     EGA or CGA
         ON OFF OFF  ON     CGA 40x25       MDA 80x25     EGA or CGA
        OFF OFF  ON OFF     MDA 80x25       CGA 80x25     MONOCHROME
         ON OFF  ON OFF     MDA 80x25       CGA 40x25     MONOCHROME


    If AST-3G Plus is the secondary video adapter

          SW1 Switch
        Block Settings                       Primary       Monitor
         1   2   3   4       3G Mode      Adapter Mode   Type (on 3G)
        --- --- --- ---   ------------   --------------  ------------
        OFF OFF  ON  ON     EGA 80x25       MDA 80x25     EGA
         ON OFF  ON  ON     CGA 80x25       MDA 80x25     EGA or CGA
         ON  ON  ON  ON     CGA 40x25       MDA 80x25     EGA or CGA
        OFF  ON OFF  ON     MDA 80x25       CGA 80x25     MONOCHROME
         ON  ON OFF  ON     MDA 80x25       CGA 40x25     MONOCHROME

    SW2 - Emulation Switch

        By turning on the emulation option (SW2), the 3G Plus will emulate CGA
        graphics (when SW1 is set to EGA).  This is useful for cases when your
        software does not support Enhanced Graphics.  If SW1 is set to
        monochrome mode, turning SW2 on will allow the 3G Plus to emulate
        Hercules graphics.  The emulation mode can be used with the 3G Plus in
        the primary or secondary position.


JUMPER SETTINGS

    E1 - Video Memory
        Connect for 256K; Open for 64K

    E2 - Factory Test Point
        Connect at all times

    E3/E4 - Base I/O Address
        Connect E3 side for 3xx

    E5/E6 - Parallel port address
        Connect E5 for LPT1:(378h); Connect E6 for LPT2:(278h)

    E7/E8 - Interrupt Request
        Connect E7 for IRQ5 (LPT2:); Connect E8 for IRQ7 (LPT1:)

    E9/E10 - Monitor Type
        Connect E9 for EGA monitor; Connect E10 for CGA or Mono TTL monitors


SWITCH AND JUMPER LOCATIONS

    +---------------------------------------------------------------+
    |                                                        E9/E10 | +---
    |                                                           **  +-+===
    |                                      E1 *        E2 *         | | SW2
    |                                                             +-| |
    |                                                         SW1 | | |
    |                                      E3/E4                  +-| |
    |                                         ** **                 | |
    |                                            E5/E6              | |
    |                                                               | |
    |                                                  ** E7/E8     +-+
    +---------------------------------------------+            +----+ |
                                                  +------------+      |
                                                                      |