Keithley DAS-4300 Series, Руководство пользователя, Страница: 20 / 94

Memory 2-5
Host Computer Memory
DAS-4301/8K boards require part of both the host computer I/O address
space and the host computer memory address space.
I/O Address Space
The DAS-4301/8K board uses a block of 16 bytes (ports) in the I/O
address space of the host computer to set up the board’s parameters.
These ports can be located anywhere below 400h, provided that they are
not used by your host computer. The default I/O address space for these
ports is 250h to 25Fh.
You select the base address for the I/O address space by setting jumpers
on the board; refer to page 3-12 for information.
Memory Address Space
The memory address space of the host computer is used for reading the
acquired data from the DAS-4301/8K onboard memory buffer. The host
computer accesses the onboard memory using the decoding logic on the
DAS-4301/8K.
The onboard 8,192 byte buffer memory is mapped into a 16K byte
window within the 1M byte address space in the host computer’s upper
memory (above the 640K byte user memory area). You select the base
address for the memory address space by setting jumpers on the board;
refer to page 3-14 for information. Figure 2-2 illustrates the memory
address space of a host computer.
Note: The memory map must fall on a 16K byte boundary; this memory
area must not be in use by other boards or devices.