Alto
Hardware Manual Section
9:
Nuts and Bolts
for
the Microcoder
66
It
is
believed that the standard Alto peripheral most sensitive to
task
latency
is
the Diablo disk controller
when
connected
to
a Model
44
disk drive. This
is
due
to the fact that the data rate
is
relatively high and
the controller
has
only
16
bits
of
buffering.
It
has been determined empirically that
task
latency greater than
20
microinstruction times causes Diablo
Model
44
disks
to encounter data-late errors. Therefore, when writing microprograms, it
is
essential that
you
issue a
TASK
at least once
every
20
microinstructions (preferably once
every
15). When counting
microinstruction times,
do
not forget
to
include
the
cycles
during which the processor
is
suspended due
to
memory references.
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