AST 5251/11                                         AST Part Number 202027-001
AST 5251/11 PLUS                                    AST Part Number 202027-002

This board is for local communication with IBM system 34/36/38 and AS-400.
There are five settings on this board that need to be configured or checked by
the user before installation.  These are

    - Station address and type selection switch block.
    - Terminator selection jumper block.
    - DMA channel selection jumper block.
    - IRQ selection jumper block.
    - I/O address selection jumper block.

There are two switch blocks with eight toggle switches on each block.  Even
though this switch allows to set the work station addresses, the software
overrides these switch settings.  It is recommended to use switch nos.7 and 8
in "ON" position on the switch bank SW1, and switch no.7 in "ON" position on
the switch bank SW2 when the emulation program is run with software version
3.1 or above.

There are two DMA jumper blocks which allow to set the board to use one DMA
channel out of the available three channels.  Factory default settings are DMA
1 and it works with PCs, XTs, ATs and their clones.

There is one IRQ jumper block with four IRQ lines 2,3,4 and 5.  Factory
default setting is IRQ 2.  If any other board or device is using IRQ 2 then
the emulation board gives an error message during execution of the Kernel
program.  In such case IRQ 3 or 5 is recommended.

There is one I/O address jumper block with four I/O address ranges 250h, 350h,
450h and 550h.  Factory default setting is for I/O 250h and may need to be
changed when the board is installed on some clones.

The terminator selection jumper block located at the top right corner of the
board allows to run the emulation either from end of the line when in
"terminated" mode or from the middle of the line when in "through" mode.  When
the two jumpers are removed from this block the board is set in "through"
mode.


SWITCH AND JUMPER LOCATIONS

    ͻ
    +-----+                                       TERMINATION | |   
    |S1-S8|+-----+                               JUMPER BLOCK      Ķ
    +-----+|S1-S8|                                                  
      SW1  +-----+                                 --250            
             SW2                                      :  I/O ADDR   
                                                     550  JUMPER    
                                                           BLK      
                              JUMPER     IRQ   DMA  DMA             
                              BLOCKS     |:::  |::  |::             
                                         2345  123  123            Ķ
    ͻ            ͼ 
                                                  ͼ      
                                                                      
