AST RESEARCH TECHNICAL BULLETIN TB-0180                   5-12-86


        AST-5251/MODEL 12 VERSION 3.3 WITH IBM SYSTEM/34


The  information contained in this Technical Bulletin pertains to 
the  AST-5251/Model 12,  installed in an IBM  Personal  Computer, 
that  has  established  connection  with  an  IBM  System/34  via 
synchronous modems through a dial-up line.

Under the following conditions, a situation can arise whereby the 
PC could exhibit these symptoms:

    Symptoms:

    1.  The display screen will go blank.

    2.  The "System Available" indicator will stay highlighted. 
   
    3.  Any  input from the keyboard will generate an error  code         
        #0099  and  the "Input Inhibit" indicator will be  turned 
        on.  Hitting  the  error reset key will clear  the  error 
        message.  However, any input from the keyboard will still 
        generate the error code.

    Conditions:
       
    1.  The  PC  is  in emulation  mode  when  a  termination 
        request is executed.

    2.  There   are  print  jobs  still  outstanding  in  the 
        System/34's  spoolfile when the  termination  request 
        was executed.

These  symptoms  occur  due to the fact  that  the  System/34  is 
expecting  the  spoolfile  to  be  cleared  or  reset  before  it 
terminates the connection.   In order to bring the PC out of this 
"loop",  a  shift-shift-ESC  key sequence is needed.   This  will 
bring the PC back to DOS.   At this point in time, all previously 
established  connections  with the System/34 will  be  lost,  and 
normal  dial-up procedures are required to bring the PC back  on-
line.   It  is also important to note that an  IBM-5251/Model  12 
will respond in a similar manner given the identical scenario.

The  suggested  solutions  to  this  particular  problem  are  as 
follows:

    1.  Before  attempting to execute a termination  request, 
        check  the System/34's spoolfile for any  outstanding 
        print jobs.  If there are print jobs in the spoolfile 
        be sure to clear it, and then execute the termination 
        request.

    2.  If  step #1 is not convenient,  then the shift-shift-
        ESC  key sequence previously mentioned  is  required.  
        This  will  bring  the PC back  to  DOS.   When  this 
        procedure  is taken,  the System/34 will generate  an 
        SDLC  error indicating that it has lost communication 
        with  the terminal.   This System/34 error has to  be 
        answered before proceeding any further.  Now with the 
        previous   connection  terminated,   normal   dial-up 
        procedures are required to bring the PC back on-line.