Commodore Amiga A500 Technical Reference Manual page 83

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 t o 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 t o allow clocked logic t o be used in designs instead
of delay lines. See p. 39 for bus loading specs.
This is a 3.58 MHz clock synched t o 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 t o 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 ( 9 0 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 5 0 .