Clock Cycles; Switches - HP Vectra Reference Manual

Clock Cycles
The memory expansion card operates from the 80286
microprocessor clock at a frequency of 8MHz. It takes three clock
cyles (one wait-state) for memory access.
Switches
The address selection switches can be set so the memory
expansion card can cover the entire 16 megabytes of system
memory space in 512 Kbyte or 1024 Kbyte blocks. However, the
processor board RAM is hardwired to the first megabyte of
memory space. Therefore, address selection switches, SW1 and
SW2, must be set to cover different blocks of the remaining 15
Mbyte memory address space. No two cards should be set to
respond to the same address space.
The memory expansion cards must be configured to reside in
sequential memory address within the system address space
100000 to FDFFFF hex. The first expansion memory address starts
at 100000 hex. Configuration is done by setting the switches,
SW1 and SW2. If more than one card is used, no gaps between
memory are allowed. Switch settings for the HP45974A 1 MB
Memory Expansion Card are given in figure 24, and switch
settings for the HP45973A 1/2 MB Memory Expansion Card are
given in figure 25.
This drawing shows the location of the switches on the memory
expansion cards, HP45973A or HP45974A.
116 Memory Expansion Cards