edtasm.doc

Edt/Asm is a basic editor with integrated in-memory assembler.  Edt/Asm was
designed so that it could be run from ROM.  The default assembly is at 8000h,
with the text editor buffer at 1000h.  In this configuration programs can be
assembled from 0000h-0FFFh.  There are two ORG addresses in the Edt/Asm source
the first specifies where Edt/Asm will be assembled, the second one (near the
end of the source file) specifies where Edt/Asm's data begins.  Any memory
below the second ORG value is available for assembled programs.
A restart address is provided 3 bytes above the normal entry point.  The 
restart address resets the baud rate and nothing else.  This entry can be used
either in non-volitile memory systems to recover the current edit buffer, or
can be used by assembly language programs to return control to Edt/Asm without
losing the editor contents.

Editor Commands:
----------------
          A       - Assemble the program
          B       - Move to bottom of buffer
          D       - Move down one line
        ,nD       - Move down n lines
          Itext   - Insert text at current location
         nItext   - Move to line n, then insert text
          I       - Enter multi-line insert mode, end with <CTRL><C>
         nI       - Enter multi-line insert mode starting at line n,
                    end with <CTRL><C>
         nG       - Make line n the current line
          K       - Kill (delete) the current line
         nK       - Move to line n, and then delete line
        ,nK       - Kill n lines starting from current line
       n,mK       - Kill m lines starting from line n, n becomes current
          N       - New file - clears buffer
          P       - Print the current line
         nP       - Print line n
        ,nP       - Print n lines starting from current line
       n,mP       - Print m lines starting from line n
          R       - Run program
          T       - Move to top line of buffer
          U       - Move up one line
        ,nU       - Move up n lines
          Q       - Quit to monitor (0F900h, or 08003h on Elf2K)
          V       - Switch to Visual/02 (Pico/Elf only)

Assembler Line Format:
----------------------
label:   OPCODE   ARGUMENTS      ; Comments

Labels and comments are optional, and not all opcodes have arguments.  In 
addition to the 1802 instruction set, Edt/Asm provides 4 pseudo-opcodes:

ORG    addr            Specify address for assembly
DB     b1,b2,...bn     Define a list of bytes in memory
DW     w1,w2,...wn     Define a list of words in memory
END    start           End of assembly, also specifies atart address

Edt/Asm currently only supports simple arguments, arithmetic expressions
cannot be used.  When specifying registers, the register number may (but need
not) begin with R, for example:    LDN    R8

The high byte of a value can be obtained by addeing .1 to the end of a label,
for example:    LDI    STACK.1     will load the high byte of the address of
STACK.  .0 will obtain the low byte of a value, for example:   LDI   STACK.0