tween all Expansion Slots. The terms
86
Pin Slot, Coprocessor Slot,
and
Local Slot
are considered synonyms, and pertain to the
86
pin
Coprocessor Slot in the A2000 and
B2000. The terms
86
Pin Edge
and
Expansion Edge
are considered synonyms, and pertain to the
86
pin Expansion Edge in the A1
000
and A500. The
Local Bus
is
the
processor bus directly connected to the
68000
processor and the
Coprocessor Slot or Expansion Edge; both the Coprocessor Slot and
Expansion Edge are considered Local Bus Ports. Each different im-
plementation of a hardware design
is
termed an
Instance
of that de-
sign; thus, the
A2000's Expansion Bus, the B2000's Expansion Bus.
and all third party ZORRO backplanes for the
AI
000
or
A500
are in-
stances of the Expansion Bus.
Along with an understanding of Amiga bus terms, a familiarity with
Motorola's
68000
processor and
its
characteristic names and related
terms will also be very useful in understanding this section.
POWER CONNECTIONS
The Expansion Bus provides several different voltages designed to
supply expansion devices. The A2000 power supply
is
a "switching"
power supply, currently rated at 200 watts, which supplies the main
board and all other expansion ports, as well as the Expansion Bus.
Digital Ground (Ground)
Digital supply ground used by all expansion cards as the return path
for all expansion supplies. This
is
found on all instances of the Expan-
sion Bus. See the Table at the end of
this
section for pin assignments.
Main Supply
(
+
W)
Main power supply for all expansion cards, and is capable of sourcing
large currents; each Expansion Slot can draw up to 2.0 Amps of
+
5,
and a single Slot can draw as much as
4
Amps if necessary, for de-
vices such as
8
megabyte RAM cards. The maximum supply current
for the entire A2000 system
is
20 Amps on the
+
5
supply. All ports
open to the outside of the box have their own, separate
+
5V
supply
that's short protected, thus no loads external to the A2000 box need
be considered. This supply
is
found on all instances of the Expansion
Bus, though the available currents may vary. Pins:
5,6.
Negative Supply
(
-
W)
Negative version of the main supply, for small current loads only;
there's a total of 0.3 Amp for the entire A2000 system. Found on all
instances of the Expansion Bus, though the available currents may
vary. Pin:
8.
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