VXI?Corporation F80 Especificaciones descargar pdf (Pagina 43)

Pentek Model 6526 Operating Manual Page 43

Rev. A

3.4 VMEbus A16 Slave Memory (continued)

3.4.4 VMEbus Unique A24/A32 Base Address Register (continued)

3.4.4.2 VMEbus Unique A24 Base Address − Bits D7 to D1

These seven bits specify the lowest address in the region of VME−

bus A24 address space that this Model 6526’s unique A24−addres−

sable resources will occupy. The board may occupy one of 128

regions, each representing 128 kBytes of VMEbus A24 address

space. The value set in bits UA24_6 to UA24_0 in this register

should be unique for each Model 6526 in the system, so that when

commands are issued in this address space, only the desired board

will respond.

VME address bits A23 – A17 (the third and fourth hex address

digits) are compared with the contents of this register field to

determine if this is the board being addressed. Note that this value

corresponds to the “VME_base” designation used in the A24/A32

address map descriptions in Section 3.5.

NOTES:

(1) Because the Model 6526 occupies 128 kBytes of VMEbus

memory in A24 address space, it can only be mapped on EVEN

A24 VME_base addresses. Therefore, the least significant bit of

this register must always be written with a logic '0'.

(2) The contents of the eight least significant bits in this register

have no effect upon the Unique A32 base address. In other

words, if you write 0xDCBA to this register, the Unique A32

base address is 0xDC00 0000, and the Unique A24 base address

is 0xBA 0000.

1 2 ... 38 39 40 41 42 43 44 45 46 47 48 ... 195 196

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VXI?Corporation F80 Especificaciones Pagina 43