The first disk drive for the Altair 8800 was an 8-inch drive. Technology moved fast and chaotically in those days, and it wasn’t long after that the Mini-Disk drive was released, using 5.25″ diskettes. The Mini-Disk system was less expensive, but had less storage capability (approximately 72k.)

Step-by-Step:

1. Stop whatever the Altair is doing – raise “Stop”, then raise “Reset”.
2. Mount emulated disk 14 in drive 0 – switch 12 up, switch 3 up, switch 2 up, switch 1 up (all other switches down).
3. AUX2 down to load disk.
   Terminal will say “[mounted disk ‘DISK0C.DSK: ALTAIR Mini-Disk DOS’ in drive 0]”
4. Mount emulated disk 13 in drive 1 – switch 12 up, switch 8 up, switch 3 up, switch 2 up, switch 1 up, switch 0 up (all other switches down.)
5. AUX2 down to load disk.
   Terminal will say “[mounted disk ‘DISK0D.DSK: ALTAIR Mini-Disk DOS programs’ in drive 1]”
6. To run bootable disk – switch 3 up (all others down).
7. AUX1 down. This will install the Disk Boot ROM and boot disk 0.
   Terminal will load Altair Mini-Disk BASIC and ask “MEMORY SIZE?”
8. Press Enter.
9. For “INTERRUPTS?” respond “Y”.
10. Answer 1 for “HIGHEST DISK NUMBER?” (That means two disks.)
11. For “DISK FILES?” and “RANDOM FILES?” you can answer 4.
12. The terminal will show
    055817E 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 1” – mount drive 1.
“DIR 1” – get a directory of drive 1.