

                                 SHOW87
                                 ------
    Copyright (c) 1988, 1993 Borland International  All Rights Reserved

TABLE OF CONTENTS
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1. What is SHOW87?
2. Starting SHOW87
3. What SHOW87 Displays


1. WHAT IS SHOW87?
------------------

  SHOW87 is a memory-resident program that displays the entire state of an 
  installed 8087 coprocessor chip when an 8087 is present. This is useful 
  when you're debugging code that contains 8087 instructions.


2. STARTING SHOW87
------------------

  SHOW87 has two modes of installation. The default is the shell mode in 
  which SHOW87 executes a DOS shell, rather than making itself truly resident.
  This allows you to de-install SHOW87 by typing EXIT at any DOS prompt. The
  disadvantage of the shell mode is that a second command processor must be 
  invoked, which uses an extra 3,000 to 4,000 bytes of memory. The other 
  installation mode is the resident mode, which is specified by the /r 
  parameter. SHOW87 uses less memory in this mode, but cannot be removed. 
  SHOW87 alone uses about 5,900 bytes of memory.

  Once installed, SHOW87 can be invoked at any time by pressing Alt-7. 
  Invoking SHOW87 causes most of the upper half of the screen to display the 
  flags, registers, and other information regarding the 8087. Pressing any key
  exits you from the display and restores the screen. Normally, you would 
  install SHOW87 before debugging 8087 code and then remove SHOW87 when it's 
  no longer needed.

  If SHOW87 cannot properly install itself, it will display an error message 
  and terminate. The most common reasons for such an error are insufficient 
  memory, COMMAND.COM not found, or no 80x87 is detected. COMMAND.COM is only 
  needed when SHOW87 is run in shell mode. SHOW87 finds the COMMAND.COM file 
  by looking for the COMSPEC parameter in the environment (see your DOS manual).


3. WHAT SHOW87 DISPLAYS
-----------------------

  SHOW87 displays all 8087 information, including the instruction pointer, the
  operand pointer, the operation code; the control, status, and tag words; the
  precision, rounding, and infinity control settings; the stack top; the 
  condition codes and their various interpretations; the exception settings 
  and interrupt mask settings; and the register values.

  The condition code settings represent C3, C2, C1, and C0 respectively. 
  The Comp, Test, and Exam fields display the meaning of the condition codes 
  as returned by the FCOM, FTST, and FXAM instructions.

  Register values are displayed in one of two ways. If the number has a tag 
  setting of VALID, the number is displayed in decimal format. If the number
  has a tag setting of SPECIAL or EMPTY, a hexadecimal dump of the number is
  displayed. After the mantissa and exponent, the type of value (as 
  interpreted by the FXAM instruction) is displayed.
 
