AMOS Professional

AMOS Professional (often shortened to AMOS Pro) is the most advanced version of AMOS BASIC, the games-and-multimedia BASIC that François Lionet wrote for the Commodore Amiga. Europress Software launched it in autumn 1992 as a complete overhaul of the original AMOS (1990). It combined feedback from users with ideas from the beginner-oriented Easy AMOS. The result was a BASIC that the manual says provides “over seven hundred command words,” wrapped in a reconfigurable editor with on-line help, a step-through program monitor, a built-in language for dialogue boxes, ARexx support and direct access to AmigaOS libraries.

AMOS Pro was never an operating-system-friendly development tool the way C or Amiga E were. It was built to take over the machine and move sprites, play music and draw screens quickly, and that made it one of the main ways Amiga hobbyists wrote games in the 1990s.

History & Origins

From STOS to AMOS

AMOS grew out of STOS BASIC, Lionet’s games BASIC for the Atari ST, which Mandarin published in the UK as The Games Creator. The “potted history” in the AMOS Professional User Guide tells the story in dates:

AMOS Professional is therefore a 1992 product. The 1990 date often attached to “AMOS” belongs to the original AMOS, which AMOS Pro replaced. The manual records that AMOS programming was interrupted on 19 March 1990, when Lionet was conscripted into the French army, and was “completed in uniform, in secret and under stress.”

Building the professional version

In the manual’s welcome, Europress’s Chris Payne writes that “François made so many improvements to the original environment that we had to give AMOS a complete overhaul, and the result is AMOS Professional.” Project manager Richard Vanner explains that instead of dictating the new version, the team “contacted over two hundred AMOS enthusiasts” and built a wish list of features from their answers.

A mini-review posted to comp.sys.amiga.reviews on 29 October 1992 credits François Lionet as main programmer, Mel Croucher as manual author, Stephen Hill as technical author, Ronnie Simpson as demo programmer and Richard Vanner as project manager. It gives the list price as £69 (US$111), with a £30 upgrade for registered AMOS users. The package came on six disks with a spine-bound manual. The reviewer, who described himself as more comfortable with C than BASIC, concluded that “for current Amos users it is a great step forward.”

Version 2 and the compiler

Like AMOS before it, AMOS Pro ran as an interpreter. The AMOS Pro Compiler, © Europress Software 1993, compiled programs into 68000 machine code. It came with an updater that took AMOS Pro to version 2.x, which the compiler manual calls “a major enhancement over the original AMOS Professional package” because it “integrates the AMOS Pro Compiler with the Editor, adds many additional features and fixes a number of problems.” Owners had to upgrade because the compiler would not work “with any of the previous versions of AMOS Pro (including 1.12).” The same compiler also accepted programs written for the original AMOS and for Easy AMOS.

Version 2.00 was the end of the line. Lionet later wrote that the source he published reflects AMOS Professional “as it was on my machine at the end of 1993 when I decided to switch to PC and create Klik and Play with my partner Yves Lamoureux,” the product that led to Clickteam.

Design Philosophy

• Games first. The manual opens by claiming that “there is not a single style of best-selling computer game that cannot be produced with AMOS Professional.” Sprites, “Bobs” (blitter objects), screens, scrolling, samples and music modules are all built into the language.
• Everything explained on screen. AMOS Pro’s answer to a steep learning curve was context-sensitive help. The reviewer described it this way: put the cursor on a command, press the Amiga’s Help key, and a help screen appears. The disks also held hundreds of ready-made examples.
• A configurable environment. Lionet’s own note in the manual says the editor “can be reconfigured to exactly how you like it, and I mean exactly. You can even reprogram my menu options.” The 1992 review called configurability “the single greatest improvement.”
• Mini-languages for special jobs. AMOS Pro kept AMAL, the AMOS Animation Language, for animating objects independently of the main program, and added a separate Interface language for dialogue boxes and control panels.

Key Features

Structured BASIC

AMOS Pro is a line-oriented BASIC without mandatory line numbers. It has labels, named procedures with parameters, local variables by default, and structured loops (Do/Loop, While/Wend, Repeat/Until, For/Next) with Exit to leave them early. Variable types are marked with sigils: plain names are integers, # marks floating point and $ marks strings. New in AMOS Pro is Else If for multi-way tests:

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If A=1
  Print "A=1"
Else If A=2
  Print "A=2"
Else If A=3
  Print "A=3"
Else
  Print "Something Else"
End If

Procedures, parameters and globals

Procedures take parameters in square brackets. A procedure returns a value by putting an expression after End Proc, and the caller reads it with Param, Param# or Param$. Shared and Global make variables visible inside procedures. This example comes from the manual:

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JOIN_STRINGS["one","two","three"]
Print Param$

Procedure JOIN_STRINGS[A$,B$,C$]
  Print A$,B$,C$
End Proc[A$+B$+C$]

Procedures can also be called on a timer (Every 50 Proc TEST), when the program is interrupted (On Break Proc), or when an error occurs:

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On Error Proc HELP
Do
  Input "Type in two numbers";A,B
  Print A;" divided by ";B;" is ";A/B
Loop

The Interface language

AMOS Pro’s Interface is what the manual calls “a complete language in its own right, dedicated to the single task of generating attractive dialogue boxes, buttons and control panels.” Interface programs are written inside strings as pairs of capital-letter instructions and run with Dialog Box or Dialog Open. The manual adds that Interface even “provides fully-operative procedures and user-defined functions.” One button definition looks like this:

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BUtton 1,120,16,40,10,0,0,1;[In 1,0,0; GB 0,0,33,10; PR 1,2,'Quit',4;][NoWait,BQ;]

AMOS Pro’s own Help system was written this way, and the manual calls it “a typical example of the Interface in action.”

Reaching the Amiga’s hardware and OS

Where the original AMOS kept mostly to its own world, AMOS Pro added:

• ARexx support, so AMOS Pro programs could exchange messages with other ARexx-capable applications
• System library calls through Lib Open/Lib Call, plus direct shortcuts such as Doscall, with an equates file so functions could be named instead of given as raw offsets
• Serial and parallel port commands
• Music module playback for Tracker (Noisetracker) and MED modules, in addition to AMOS’s own music format
• Extensions: the configuration system has slots for 26 extensions, which third parties used for everything from MUI interfaces to faster rendering

Development tools

The October 1992 review lists a redesigned editor with pull-down menus, split windows and a “much improved file selector”; a monitor for stepping through programs at different speeds; a revised Object Editor with an animation previewer; and accessories including a menu builder, AMAL editor and monitor, resource manager and sample bank maker. Accessories are ordinary AMOS Pro programs that can be called up “over” the program being edited. The editor also had a Check 1.3 option that tested whether a program would still run under the older AMOS v1.3.

Evolution

AMOS Pro’s biggest gap was the Amiga’s AGA chipset (A1200/A4000). The Scorched Tanks 1.85 documentation from 1995 calls its 64-colour mode “as AGA as it gets until an AGA extension for AMOS Pro.” A later plan, reportedly by an Italian developer, to build an AGA-capable, more OS-friendly “AMOSPro V3” from the sources was dropped and never made public. Only after the source was freely available did Frédéric Cordier’s AMOS Professional AGA (first alpha September 2020) and AMOS Professional Unity (first public alpha March 2021, alpha 3/version 0.4 in August 2023) add AGA graphics. Unity also restored compatibility with AMOS Pro 2.0 memory banks, which the earlier AGA version had lost.

Current Relevance

AMOS Professional is a historical product. It was never updated by its original author after 1993 and runs on 68000-family AmigaOS machines or emulators. Like the original AMOS, it largely drives the hardware directly rather than going through AmigaOS interfaces, which caused non-standard user interfaces and compatibility problems on later Amiga hardware.

Even so, it has an unusually active afterlife for a 1992 BASIC:

• The complete 68000 assembly source is freely available, under the MIT licence in Lionet’s official GitHub repository.
• The manual is preserved online, including an HTML and PDF edition on Aminet (2008).
• New AMOS Pro add-ons still reach Aminet, such as a dark editor theme (March 2024), a Christmas-lights demo (December 2025) and, in September 2026, the AMOS Pro source of the 1996 dungeon crawler Oracle.
• Cordier’s Unity source repository was still receiving commits in August 2025.
• Lionet’s own AOZ Studio carries the AMOS dialect forward as a BASIC-to-JavaScript transpiler for the browser.

No Docker image exists, since AMOS Professional needs AmigaOS on real hardware or an emulator.

Why It Matters

AMOS Professional was the most polished version of a line of BASICs that let a generation of home-computer users write games without learning 68000 assembly or the Amiga’s ROM Kernel Manuals. Its October 1992 reviewer summed it up this way: it offers “a much smoother introduction to a machine which is complicated. The return on effort is more immediate.”

It also belongs to one of the longest careers in consumer game-creation tools. The same author went from STOS and AMOS to Klik & Play, the Clickteam products and, three decades later, AOZ Studio, and the idea running through all of them is that making games should be possible for people who are not professional programmers.