High
Voltage Supply
Higher voltage supply, useful for communications cards and other
(+
Izv)
devices requiring greater than digital voltage levels. This
is
intended
for small loading only; there's a total of
8
Amps for the entire A2000
system, much of which
is
normally devoted to floppy and hard disk
drive motors. Found on all instances of the Expansion Bus, though
the available currents may vary. Pin: 10.
Negative High
Supply
Negative version of the high voltage supply, also commonly used in
(-
Izv)
communications applications, and similarly intended for small loads
only; there is a total of
0.3
Amp for the entire A2000 system. This
pin is an extension of the original Zorro specification, and
is
found in
all A2000 machines. Pin: 20.
CLOCK
SIGNALS
/C1 Clock
/C3
Clock
CDAC Clock
E
Clock
The Expansion Bus provides clock signals for expansion boards. They
are generally used to allow clocked logic to be used in designs instead
of delay lines. See p.
39
for bus loading specs.
This
is
a
3.58
MHz clock synched to the falling edge of the 7.1
6
MHz
system clock. Also known as
ICCK
in some places. Pin 16.
This
is
a
3.58
MHz clock synched to the rising edge of the 7.1
6
MHz
system clock. Also known as
ICCKQ
in some places. Pin 14.
This
is
a 7.1
6
MHz clock that leads the 7.1
6
MHz system clock by
70ns (90 degrees). Pin 15.
This
is
the
68000
generated
"E"
clock, used for
6800
family peri-
pherals driven by "E" and
6502
peripherals driven by PH12. This
clock
is
six 7.1
6
MHz clocks high, four clocks low, as per the
68000
spec. Pin 50.
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