IBM 5114 Maintenance Information Manual page 124

head/carriage assembly: Two read/write heads
mounted on common carriage.
hub: See drive hub.
Hz: Hertz.
lAD: Installation activity document.
Kg: Kilogram.
KHz: Kilohertz.
LED (light emitting diode): An electronic part used as
a source of light.
logical record: A collection of related items. Portions
of a logical record can be located in different physical
records.
MAP: Maintenance analysis procedures.
MFM (modified frequency modulation): See
modulation.
MIM: Maintenance information manual.
mm: Millimeter.
modulation: The process of varying the amplitude and
frequency of the read and write signals.
ms: Millisecond.
mV: Millivolt.
ns: Nanosecond.
physical record: One or more records written one
sector on a track.
PTX (phototransistor): An electronic part used to
sense the light of an LED.
8-2
R/W:
See read/write.
read/write (R/W): Refers to the function of reading
data from and writing data to a diskette.
record: A collection of related items of data, treated as
a unit.
rpm: Revolutions per minute.
solenoid: An electromechanical part that operates the
bail assembly to load and unload the read/write heads.
spanned record: A logical record stored in more than
one block.
stream files: Records of varying length that must be
read sequentially.
V: Volt.
Vac: Volts alternating current.
Vdc: Volts direct ·current.
VFO (variable frequency oscillator): An electronic
circuit used to synchronize the read and write circuits
with diskette rotation in FM and MFM recording.
wiper assembly: A small plastic cover with a foam
wiper that protects and cleans the drive band.