Hierbei handelt es sich um einen sogenannten System-Monitor, mit dem der Ablauf eines Programmes überprüft und überwacht werden kann.
Developer : (Uncredited on the German release) J. Rued, according to the US V1.0 version. Date : 1983 — confirmed directly in the binary: *** ATAMON V1.3 - (c) 1983 by ATARI *** Distributed by : ATARI Elektronik Vertriebs GmbH – Bebelallee 10 – 2000 Hamburg 60 Dump : Download – Source Atarinside – Updated March 2026. Boot with the Option key (BASIC disabled), then load the binary file from DOS (see below).
The archive contains:
File
Description
Atamon - D7 - DXG 5724.PRO
Original disk image — .PRO format
Atamon - D7 - DXG 5724.atr
Original disk image — standard .ATR format
Atamon - D7 - DXG 5724-Patched Atarinside.atr
Patched .ATR — C command bug corrected
Atamon - D7 - DXG 5724_ATAMON.xex
Extracted ATAMON binary (Atari XEX format)
Atamon-sourced-commented.txt
Full annotated 6502 disassembly (2 659 lines)
ATAMON_DOCUMENTATION.md / .html
Complete reference documentation — French
ATAMON-DOCUMENTATION_EN.md / .html
Complete reference documentation — English
ATAMON-DOCUMENTATION_DE.md / .html
Complete reference documentation — German
Other translations : A US V1.0 version exists on ftp.pigwa.net as a .COM file only. Differences with the German V1.3 are unknown beyond the title screen.
Story : There is just one reference to this software in the Atari German software catalog of 1983. The original disk is formatted with DOS 2.0s. No original box or packaging has ever been found — an original cover design has been created for this page. It’s one of the rarest software produced by Atari Germany.
What is ATAMON?
ATAMON is a machine language monitor for the Atari 800XL — a tool that lets you see, modify, and execute 6502 instructions directly in memory, without any intermediate language.
With ATAMON you can:
Inspect memory — display any RAM area, byte by byte
Modify memory — patch values, fix bugs, tweak games
Disassemble programs — translate raw machine code into readable mnemonics (LDA, JMP, STA…)
Execute and debug — run a program and regain control at every BRK breakpoint, with full CPU register display
Read/write disk sectors — direct sector access via commands E and W
Calculate — hex/binary arithmetic directly from the command line
How to load your program into ATAMON
Load ATAMON first, then exit to DOS (command X) — ATAMON stays resident in memory at $4000. Load your program using the DOS L option with the /N suffix (no auto-run), then restart ATAMON with M 4000.
Your program’s start address is stored at $02E0 — read it with M 02E0, launch it with G.
ATAMON will intercept any BRK instruction or crash from that point on.
A bug found — and fixed
The C command (write bytes in binary notation) has been broken since the original 1983 release — it always returns ? (Error). The cause was identified in the disassembly: a missing separator check causes the comma between arguments to be written to memory instead of the first binary bit. A patch is included in the archive — a patched .ATR image with the fix already applied.
