HESMON INSTRUCTIONS
   
   If You've Never Used a 'Machine Language Monitor' Before
   
   The following section is intended for people who are unfamiliar with
   the uses of a machine language (M.L.) monitor program. However, it is
   not a tutorial in the architecture of the C64 or the 6502. Nor is it
   intended to teach 6502 assembly language programming. In fact, some
   knowledge of assembler language will be most helpful. It is intended
   to help the beginner get started in using HESMON. Even those who know
   nothing about the 6502 or the C64 will find some of HESMON's commands
   useful (see, for example, the Interpret Memory command).
   
   If you are familiar with the C64's screen editor, you should have no
   trouble entering and editing HESMON commands. HESMON commands are
   entered and edited just as are BASIC direct mode commands. They
   consist of a single character usually followed by one or more
   'parameters' and a RETURN. The parameters consist of hexadecimal
   numbers or character strings and are separated from one another by
   spaces. With one exception (the 'U' command) numeric parameters must
   be hexadecimal and do not need to be prefixed with '$'. String
   parameters are identified by enclosing them in double quotes ("). If
   HESMON doesn't understand a command it will print '?', usually just to
   the right of the bad command. If the command is understood, but the
   result is impossible or illegal, e.g., trying to save HESMON itself on
   tape, HESMON prints a '?' on the following line.
   
   To use HESMON, turn your C64 off, insert the HESMON cartrtdge into the
   expansion slot In the C64 and then turn the power on. You will see the
   HESMON version number, the programmars name, the H.E.S. copyright
   message, and the 'cold start' register display:
   
       C.
      
        PC   IRQ SR AC XR YR SP
       0000 EA31 27 0n 00 00 FA
   
   The meaning of this rather cryptic display is as follows: The first
   line 'C' identifies a cold start of HESMON, that is, starting up from
   power-on. The next line identities the pseudo 6502 registers
   maintained by HESMON:
   
       PC = program counter
      IRQ = interrupt request vector
       SR = status register
       AC = accumulator
       XR = X register
       YR = Y register
       SP = stack pointer
   
   NOTE: "6502" is used synonomously for "6510" in this document.
   
   The register contents are shown on the third line. The quantities
   shown in the register display (except the IRQ) are not the actual
   register contents, they are the numbers HESMON will use to set the
   6502 registers when instructed to begin execution of a M.L. program.
   IRQ is not a 6502 register, but a RAM 'vector' that points to an IRQ
   interrupt service routine. Beginners may ignore this location - but
   better not change it! The ';' at the beginning of the last line is
   really a HESMON command. It tells HESMON (if the RETURN key is pressed
   with the cursor on this line) to put the seven numbers that follow
   into the corresponding pseudo registers. Just before beginning
   execution of a M.L. program HESMON copies the pseudo register contents
   to the 6502 registers. so, for example, If we want the C64 to print
   'HI.', we could first move the cursor up to the ';' line and alter it
   to read:
   
      1200 EA31 27 48 49 2E FA
   
   When we press RETURN, the 6502 pseudo program counter is set to $1200,
   while the accumulator, and X and Y pseudo registers are set to $48
   (ASCII H), $49 (ASCII I), and $2E (ASCII). Now, if we write a program
   at $1200 to print the AC, XA, and YR it will print 'HI.' when we
   execute the HESMON Go command. Let's write such a program using the
   HESMON simple Assembler command, 'A'. Type in the following lines:
   
      A 1200 JSR FF02
      TXA
      JSR FF02
      TYA
      JSR FF02
      BRK
   
   The 'A' beginning the first line tells HESMON we wish to assemble,
   that is, translate assembly mnemonics into machine code. As you press
   RETURN after typing each of the above lines, you will see HESMON
   reprint the line, showing the machine code generated from the assembly
   language instruction. HESMON will then prompt for the next line of
   program by printing the 'A' command and the next available address
   followed by
   
            K.J. REVEALED TRILOGY    PAGE [161]    (C)1990 K.J.P.B.