Load Altair DOS 1.0

Chris DavisFun Things To Do

Altair DOS 1.0 was announced in late 1975 when the Altair floppy disk system was released. However, it was not actually released until August of 1977. By then, CP/M had become the defacto operating system for Altair disk systems.

Requirements:
MicroSD Card with Altair disk images (available here.)
Terminal software (Putty is highly recommended.)

Step-by-Step:

  1. Stop whatever the Altair is doing – raise “Stop”, then raise “Reset”.
  2. Mount emulated disk 2 in drive 0 – switch 12 up, switch 1 up (all other switches down).
  3. AUX2 down to load disk.
    Terminal will say “[mounted disk ‘DISK02.DSK: ALTAIR DOS 1.0’ in drive 0]”
  4. To run bootable disk – switch 3 up (all others down).
  5. AUX1 down. This will install the Disk Boot ROM and boot disk 0.
    Terminal will load Altair DOS 1.0 and ask “MEMORY SIZE?”
  6. Press Enter.
  7. For “INTERRUPTS?” repond “Y”.
  8. Answer 0 for “HIGHEST DISK NUMBER?” (That means one disk.)
  9. For “DISK FILES?” and “RANDOM FILES?” you can answer 4.
  10. The terminal will show
    055797 BYTES AVAILABLE
    DOS MONITOR VER 1.0
    COPYRIGHT 1977 BY MITS INC

In general, Altair DOS 1.0 was cryptic and non-intuitive.  Turn on your Caps Lock, because Altair DOS doesn’t like lower-case.

A few commands to get you going:
“MNT 0” – mount drive 0.
“DIR 0” – get a directory of drive 0.
“PRIME” – runs the program that calculates prime numbers. Press ctrl-c to quit (which works because we enabled interupts.)