Memory
The processor extension card
on
the
processor board contains
the
system RAM
with
parity, and
the
64
Kbytes
of
system ROM. The
256
Kbytes RAM processor extension card
(HP
assembly
number
45935-60002)
can be expanded
to
a maximum
of
640
Kbytes
RAM by
128
Kbytes increments
without
additional I/O cards. The
640
Kbyte processor extension card
(HP
assembly
number
45945-
60002)
is
considered fully loaded.
ROf\ll
The processor extension card
has
four
ROM sockets;
two
at
hex
address
FOOOO
(even and odd), and
two
at hex address
EOOOO.
The
following
chart shows
where
the
ROfv1
sockets are addressed.
These sockets can accept either 16 Kbyte (16K x 8)
or
32 Kbyte
(32K x
8)
parts. The 16 Kbyte parts start
at
hex address E8000;
the
32 Kbyte parts start
at
hex address
EOOOO.
The
HP
Vectra
PC
is
equipped
with
two
32 Kbyte parts. Their
access
time
is
170ns.
Even
Odd
System
FOOOO
U183 U191
Open
EOOOa
U152 U192
RAM
The RAM chips used in
the
HP
Vectra
PC
have an
access
time
of
150ns and a cycle
time
of
275ns. The parts used
for
the
system
RAM are
256
Kbit parts (64K x 4). The parts used
for
parity are
64
Kbit parts (64K x 1). The
following
figure illustrates
the
RAM
organization.
10
Processor Board
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