Model 466-1 Adapter
12 Adapter Functions
1.8 IACK Read Operation
A SBus processor can instruct the VMEbus adapter card to perform an
Interrupt Acknowledge (IACK) cycle on the VMEbus by reading from the
VMEbus adapter IACK Read Register. The adapter converts a read of this
register into an interrupt acknowledge cycle on the VMEbus. The interrupt
level to be acknowledged is determined by the IACK code bits in the Remote
Command Register 1. The VMEbus interrupt vector is returned to the SBus
processor as data from the read.
1.9 Page Mode Operation
A SBus application may need to access a larger VMEbus address range than
the size of the Direct Mode window in SBus slot space. Access to any address
on a VMEbus system through a smaller window in SBus slot space is
supported via Page Mode.
In Direct Mode, VMEbus RAM is addressed through the 16M byte RAM
window in SBus I/O slot address space. This allows up to 16M bytes of
VMEbus memory to be accessed, without changing any adapter registers. The
window's address range is fixed by the
Bias
jumpers on the VMEbus adapter
card and cannot be changed by software.
Page Mode, however, permits addressing of all VMEbus RAM locations
through a smaller window in SBus I/O slot address space. The upper 12 - 16
address bits are provided by the Page Register located on the VMEbus adapter
card. The remaining lower address bits are provided by the address offset in
the SBus address window. It is possible to switch between direct and paged
modes under program control.
The
size
of the page also may vary under program control. Page size is
selected by code bits in the Remote Command Register 2. The smallest page
size is 64K bytes and the largest is 1M byte.
Page Mode also controls SBus access to Dual Port RAM. When Page Mode is
selected, address bits A16 through A22 to Dual Port RAM are provided by the
value in the VMEbus adapter card Page Register. Address bits A23 through
A31 are ignored.
Содержание 466-1
Страница 1: ...Model 466 1 Adapter Hardware Manual Connects a SBus Computer to a VMEbus System...
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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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