DISASM.DOC

DISASM.COM  is a program to run on the PC which will disassemble
TMS7000 microprocessor instructions.  It was custom made for
dealing with the code in U30 in the VC2.  It loads a 16384 byte
binary file from the disk and assumes the first address is hex C000.

It was not intended to disasmble a complete 16k U30!  Its primary
use is to look at short sections of U30 code to understand whats
going on.  The user can modify the code by HEX entry only.  There
is NOT an assembler in it.  It will also compute the checksum
of U30 in macom/GI format an put it at C000,C001 if desired.

Usage notes.

   It only request an input file once.  You have to exit and
   re-enter to change work files.  The "W" command over-writes
   the original work file.

   All commands MUST be in UPPER CASE !  

   [s] START <enter hex address or command here>

   The [s] or [h] before the "START" prompt indicates which
   mode (source code disassembler [s] or hex dump [h] ) To
   switch modes type "X".


   [s] END  < address or "enter" here>
   
          Note: if you don't put an end address the program will
                give you exactly one screen full of data. 

   The "H" command puts you in the hex data entry mode.  You
   can modify the code this way.  If changing anything except
   DATA areas you will need to get a copy of the TMS7000
   instruction set and manually convert instructions to
   HEX values for entry.  (What do you expect for free?)

   When in HEX entry mode you need to enter an address between
   C000 and FFFF.  It will print the address and the data at
   that location.  To change that byte hit a "space" then the
   hex byte (2 digits).  The next address and data will then
   be displayed.  To go to next address without changing data
   hit the "enter" or "return" key.  To go back to the last
   address hit the "-" key.  To enter a new address hit the
   "X" key.  To exit back to the main menu hit "Q".  When done
   you can save the modified code to disk with the "W" command.

Other commands

   CK    Compute checksum of U30
   DISK  Save all program output to disk.
   P     Toggles printer on and off
   MOVE  move a block of data
   CALC  compute relative addresses 

end.

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