IBM 5170 Technical Reference page 423

Mb. 1 048 576 bytes.
mega (M). Prefix 1 000 000.
megahertz (MHz). 1 000 000 hertz.
memory. Term for main storage.
meter (m). A unit of length (equivalent to 39.37 inches).
MFM. Modified frequency modulation.
MHz. Megahertz; 1000 000 hertz.
micro
(J-L).
Prefix 0.000 001.
microcode.
(1)
One or more microinstructions. (2) A code,
representing the instructions of an instruction set, implemented in
a part of storage that is not program-addressable.
microinstruction.
(1)
An instruction of microcode. (2) A basic or
elementary machine instruction.
microprocessor. An integrated circuit that accepts coded
instructions for execution; the instructions may be entered,
integrated, or stored internally.
microsecond (J-Ls). 0.000 001 second.
milli (m). Prefix 0.001.
milliampere
(mA).
0.001 ampere.
millisecond (ms). 0.001 second.
mnemonic. A symbol chosen to assist the human memory; for
~
example, an abbreviation such as "mpy" for "multiply".
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