AST RESEARCH TECHNICAL BULLETIN TB-0033A                   9-4-84


                  AST-5251 VER. 2.1 ADDRESSING


The AST-5251 package utilizes I/O address 300 to 30F.  If another 
peripheral board is using the same or part of this address  range 
it will be necessary to readdress the AST-5251.

To  readdress AST-5251,  the CC-432 board and AST5251.EXE must be 
reconfigured.

Locate  the switch bank (S1) on the CC-432 board.   Switches  one 
and two select the I/O address range for the CC-432.

   S1       Position        Hexidecimal          Application
    1           2          I/O Addresses

   ON          ON             300-30F          Prototype Card
   OFF         ON             320-32F          Fixed Disk
   ON          OFF            340-34F          Not Used
   OFF         OFF            360-36F          Not Used

To  patch AST5251.EXE it is first necessary to rename it in order 
for DEBUG.COM to edit it.   Type in the commands in boldface on a 
disk that has DOS, DEBUG.COM, and AST5251.EXE on it.

     A>REN AST5251.EXE AST5251.TST
     A>
     A>DEBUG AST5251.TST
     -e300          (sp = spacebar)
                   sp   sp     sp   sp     sp   sp     sp
     08FF:0300  0A.  04.  02.XX  03.  00.YY  03.  00.ZZ  03. 
                   sp
     08FF:0308  04.  DD
     -w
     Writing A000 bytes
     -q
     A>
     A>REN AST5251.TST AST5251.EXE
     A>

     (*) Where XX,  YY, ZZ, and DD equal the values in table 2-1, 
corresponding to the selected address (see below).

                             TABLE 2-1

     I/O ADDRESS          XX      YY      ZZ      DD

      300-30F             02      00      03      04

      320-32F             22      20      23      24

      340-34F             42      40      43      44

      360-36F             62      60      63      64