Model 466-1 Adapter
VMEbus Addressing 83
Appendix B: VMEbus Addressing
The VMEbus specification defines three types of address spaces: extended
(A32), standard (A24) and short (A16). Extended (A32) addressing uses 32
address bits. Standard (A24) addressing uses 24 address bits. Short (A16)
addressing uses 16 address bits. The VMEbus does not have an address 0
(A0) line. Byte addressing is controlled by the signals DS0 and DS1.
Each address space is independent of the other address spaces and can be
thought of as a logically separate address bus. A32 addressing uses address
lines A31-01. A24 uses A23-01, and A31-24 are unused. A16 uses A15-A01,
and A31-16 are unused. Address lines A03-A01 are used during Interrupt
Acknowledge cycles (IACK cycles). The following table summarizes the use
of the address bus.
ACTIVE PORTION OF ADDRESS BUS - ADDRESS ROUTING
A31 - A24
A23 - A16
A15 - A04
A03 - A01
Address Modifier
Codes (hex)
A31 ---------------------------------------------------A01
Extended (32-bit)
08 - 0F
A23------------------------------------A01
Standard (24-bit)
38 - 3F
A15-------------------A01
Short I/O (16-bit)
29, 2D
A03 - A01
Interrupt
Acknowledge
= Unused portion of address bus; should be ignored by slave device.
The value of the address modifier lines, AM[0..5], determines which address
space is used. The VMEbus master is responsible for supplying the proper
address modifier at the same time it drives the address lines. Slaves are
designed to respond to cycles with a particular address modifier; however,
some slaves are capable of responding to several address modifiers.
Содержание 466-1
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Страница 52: ...Model 466 1 Adapter 42 VMEbus Adapter Card Configuration...
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Страница 88: ...Model 466 1 Adapter 78 Common Problems And Solutions...
Страница 106: ...Model 466 1 Adapter 96 Jumper Configuration Worksheets...
Страница 107: ...Model 466 1 Adapter Jumper Configuration Worksheets 97 D 1 SBus Adapter Card Worksheet J1...
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