Canon A-1 Repair Manual page 46

(6) Memory
Since the A-l employs a method of digital memory as
in the AE-l, the data once memorized never leaks due
to changes in temperatures and swltchless, stable and
highly accurate storage is assured.
This is a very convenient way in the point that the
brightness of the subject is stored after being
converted to the digital form. An eight-bit register
is built into the memory circuit and memorizes the
digital value.
(7) Count Down Chain
The A-l has incorporated a frequency divider composed
of a 20-step flip-flop circuit which is capable of
counting down the basic frequency of 32 kHz to a
maximum of 32 sec. Various kinds of time control are
possible by combining different frequencies in between
those two extreme values.
Some practical examples are: 1/1000 - 30 sec (32 sec)
Self-timer: 2 and 10 seconds.
The LED flashes on and off in 2 Hz for the first 8
seconds and in 8 Hz for the last 2 seconds prior to
the shutter release.
Viewfinder Displays
Flashing LED for warnings (2 Hz)
Entry of new information (at every 0.5 second)
Controlled time during which the electric current is
applied to various magQets.
Anticipated time within which the mirror completely
returns to its original position when shooting conti-
nuously by means of the mo"or drive. Namely, the
time required fro the start of the second shutter
curtain's travel till the mirror's complete return
to the former position. (Approximately 112 milli-
seconds)
(8) Program Unit and Sequensor (PLA)
The A-I has incorporated a proqram unit consisting of
an versitile logical element called a (Programmable
Logic Array) or PLA for short. This program unit
contains programmed sequences of execution which
respectively corresponds to each selective AE mode
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