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assist09

README.md

This is the source for the Motorola ASSIST09 machine language monitor provided for their development boards. There are several versions here:

assist09-orig.asm - The original version that used a 6820 PIA for serial i/o and breakpoints and ran on a Motorola development board.

assist09-6522.asm - A version that was ported by A VD Horst to run on a system using a 6522 VIA.

assist09-6850.asm - A port that runs on my single board computer that uses a 6850 ACIA. The trace command is not supported.

The files will assemble with the as9 assembler found at http://home.hccnet.nl/a.w.m.van.der.horst/m6809.html

ASSIST09 Command List:

B (reak)	 <cr>	- list break points
		 NNNN	- insert break point
		-NNNN	- delete break point
		-	- delete all break points

C (all)		 <cr>	- call routine at PC as subroutine
		 NNNN	- call routine at NNNN as subroutine

D (isplay)  NNNN NNNN	- display range mod16
		 NNNN	- display 16 bytes [NNNN]mod16
		 M	- display 16 bytes [M]mod16
		 P	- display 16 bytes [PC]mod16
		 W	- display 16 bytes [W]mod16
		 @	- following NNNN, M, P, or W displays
			  16 bytes indirectly

E (ncode)	Encodes a 6809 postbyte based on the
		addressing mode syntax as follows:

			R = X, Y, U, or S

			Direct Addressing Modes
			------ ---------- -----

			     ,R		A,R
			    H,R		B,R
			   HH,R		D,R
			 HHHH,R		,-R
			   HH,PCR	,--R
			 HHHH,PCR	,R+
					,R++

			Indirect Addressing Modes
			-------- ---------- -----

			    [,R]	[A,R]
			    		[B,R]
			  [HH,R]	[D,R]
			[HHHH,R]
			  [HH,PCR]	[,--R]
			[HHHH,PCR]
			[HHHH]		[,R++]

G (o)		<cr>	- Go to PC
		NNNN	- Go to NNNN

L (oad)		Load a S1-S9 format data

M (emory)	NNNN	- Display memory data at address NNNN
		<cr>	- Terminate memory function
		/	- Display current byte with address
		<lf>	- Display next byte with address
		^	- Display previous byte with address
		,	- Skip byte
		SPACE	- Display next byte

		The / may be used as an immediate command.

		After any of the display commands the memory contents
		may be altered by inputting a valid hex number or
		ascii 'string' enclosed by single quotes (').

O (ffset)  NNNN NNNN	- Calculate the two and/or three byte offset

P (unch)   NNNN NNNN	- Punch a S1-S9 format data

R (egister)	Display 6809 registers and allow changes

		<cr>	- terminate command
		SPACE	- terminate value input or
			  skip to next register
		,	- terminate value input or
			  skip to next register

V (erify)	Verify memory against S1-S9 format data

W (indow)	NNNN	- Define a display window for the
			  D and M commands.

Ctrl-X will abort any command.