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OS 9 Tutorial

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Boisy Gene Pitre edited this page May 13, 2026 · 4 revisions

OS-9 Tutorial

Author: Bob Montowski

This tutorial is aimed at beginners who have just started using OS-9 and want help getting comfortable with the basics.

First Things First

OS-9 is not a programming language. It is an operating system, and it works very differently from BASIC.

If your goal is to program in BASIC under OS-9, you will eventually want BASIC09. But before that, it helps to get comfortable with how OS-9 itself behaves.

Booting OS-9

The original process depends on which version of Disk BASIC you have.

Disk BASIC 1.0

  1. Load the OS-9 boot disk.
  2. Type:
RUN"*"
  1. When prompted, insert the OS-9 Master Disk in drive 0.
  2. Press a key to continue.

Disk BASIC 1.1

  1. Put the OS-9 Master Disk in drive 0.
  2. Type:
DOS

Setting the Date and Time

After OS-9 starts, it asks for the current date and time.

This matters because OS-9 records timestamps on files, and those timestamps are useful for managing and identifying your work later.

Do not just press Enter. Supply a real date and time.

OS-9 uses a 24-hour clock.

Examples:

1 pm  = 1300 hours
2 pm  = 1400 hours
10 pm = 2200 hours
11 pm = 2300 hours
12 am = 0000 hours

To enter December 25, 1985 at 3:30 PM:

YY/MM/DD HH:MM:SS
85/12/25 15:30:00

To display the current date and time later, use:

DATE T

Using DATE by itself only shows the date.

How Commands Are Found

OS-9 keeps only a small number of commands resident in memory. Most commands live on disk, typically in /D0/CMDS.

When you type a command at the OS9: prompt:

  1. OS-9 checks whether the command is already in memory.
  2. If not, it searches the command directory on disk.

That means correct spelling matters. If the command name is wrong, the shell will not find it.

Speeding Things Up with load

Disk access can make command startup feel slow. One way to improve responsiveness is to preload the commands you use most often.

Example:

OS9:load dir list del attr copy

This loads the following commands into memory:

  • dir
  • list
  • del
  • attr
  • copy

After that, they are available more quickly.

The tradeoff is memory use. Loaded commands stay resident and consume RAM you may want for other work later.

The Main Beginner Mindset

The biggest adjustment when learning OS-9 is that it is a command-driven operating system with its own structure, conventions, and filesystem.

The more comfortable you get with:

  • booting
  • setting date and time
  • understanding where commands live
  • preloading the commands you use often

the faster the rest of OS-9 starts to make sense.

NitrOS-9: Empowering 6809 CPUs with a modern, efficient operating system

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