LSI M-Three Operator's Manual page 21

2.10.2 Hold the Diskette as shown in Fig. 2/4.
2.10.3
Slide the Diskette into the slot and push it in by its rear
edge until a small 'click' is heard and the Diskette is held.
2.10.4
Pull the loading slot cover across until it latches shut.
The M-TH R E E is now under the control of the software on the
'System Diskette'. This software is known as the 'Control Program'
or 'Operating System'. The standard Operating System for all
M-THREEs is CP/M (see section 5), however, if another Operating
System is to be used then the appropriate handbook should now be
consulted.
2-5