Memory; Rom; Ram - HP Vectra Reference Manual

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