January 14, 1989


Microsoft's solution to 'fixing' the DTR drop problem with QB 4.5
when closing the communications port by outputing a 3 to the 
modem status register, is not a sound or reliable solution.

Many modems simply respond too quickly to the loss of DTR.

The correct solution is to of course not turn DTR off in the
first place.  However, after many years and many versions of
Quick Basic, it is apparent that Microsoft either does not listen
to its customers or they simply do not care.
 
Sound programming practices dictate that when you directly manipulate
a hardware port, you restore that port to the exact same conditions
it had prior to your touching it.  In the case of DTR, this means
that if DTR were ON when the QB program loaded, then DTR should
remain ON when the QB program ends.  If DTR was OFF when the program
loaded, then fine, turn it OFF when the program ends.

To the end that it is an ongoing struggle to get Microsoft to listen
to the needs of the programmer, the following patches are provided
to enable you to patch your copies of BRUN45.EXE and BCOM45.LIB.
 

Before beginning, make sure you have backup copies of BRUN45.EXE
and BCOM45.LIB.
 
BCOM45.LIB DTR Patch
--------------------
 
With Debug in a DOS path, type :

  debug bcom45.lib
 
Type :
 
  s cs:0 ffff b0 00 e3 01
 
Debug should show :
 
  xxxx:1529
 
  where xxxx can be any number depending upon where Debug loaded the
  program into memory.  In any case, the number is not important.
 
Type :
 
  u 1529
 
Debug should show :
 
  MOV   AL,00
  JCXZ  152E
  INC   AX
  ADD   DX,+04
  OUT   DX,AL
 
This is where QB graciously resets the comm port to parameters it thinks
the comm port should have.
 
To fix the problem, Type :
 
  a 1529
 
  mov   al,01
  [Enter]
 
  a 152d
 
  nop
  [Enter]
 
  where [Enter] is the Enter key (do not type the characters)!
 
 
To verify that you typed everything correctly, Type
 
  u 1529

Debug should show :

  MOV   AL,01
  JCXZ  152E
  NOP
  ADD   DX,+04
  OUT   DX,AL
 
 
To save the corrections Type :
 
  w
 
Debug should show :
 
  Writing 35EF7 bytes

 
Now type Q and you are finished patching BCOM45.LIB
 


BRUN45.EXE DTR Patch
--------------------

First, rename BRUN45.EXE to BRUN45.X
 
With Debug in a DOS path, type :

  debug BRUN45.X

Type :
 
  s cs:0 ffff b0 00 e3 01
 
Debug should show :
 
  xxxx:9E78
 
  where xxxx can be any number depending upon where Debug loaded the
  program into memory.  In any case, the number is not important.
 
Type :
 
  u 9e78
 
Debug should show :
 
  MOV   AL,00
  JCXZ  9E7D
  INC   AX
  ADD   DX,+04
  OUT   DX,AL
 
This is where QB graciously resets the comm port to parameters it thinks
the comm port should have.
 
To fix the problem, Type :
 
  a 9e78
 
  mov   al,01
  [Enter]
 
  a 9e7c
 
  nop
  [Enter]
 
  where [Enter] is the Enter key (do not type the characters)!
 
 
To verify that you typed everything correctly, Type
 
  u 9e78

Debug should show :

  MOV   AL,01
  JCXZ  9E7D
  NOP
  ADD   DX,+04
  OUT   DX,AL
 
 
To save the corrections Type :
 
  w
 
Debug should show :
 
  Writing 12E80 bytes

 
Now type Q and you are finished patching BRUN45.X
 
Rename BRUN45.X back to BRUN45.EXE



The ever powerful Code View debugger was used to to find these
addresses by tracing a QB program which had but two statments :
 
  OPEN com port
  CLOSE com port
 


Any questions may be addressed to :
 
   Kenny Gardner
   The Crow's Nest BBS
   (714)493-3819
 
     CIS : 76054,210
   Genie : K.L.Gardner


This text file is (C) Copyright 1989 by GAP Development Company
Permission is hereby granted to distribute this text, and use
the information contained herein provided that this notice and
the contents of this file not be altered.