DEC 4000 AXP Service Manual page 226

processor machine check
Processor machine checks indicate that a processor internal error was detected
synchronously to the processors execution and was not successfully corrected by
hardware or PALcode. Examples of processor machine check conditions include
processor B-cache buffer parity errors, memory uncorrectable errors, or read
access to a nonexistent location.
processor module
Module that contains the CPU chip.
program counter
That portion of the CPU that contains the virtual address of the next instruction
to be executed. Most current CPUs implement the program counter (PC) as a
register. This register may be visible to the programmer through the instruction
set.
program mode
See operating system mode.
quadword
Eight contiguous bytes starting on an arbitrary byte boundary. The bits are
numbered from right to left, 0 through 63.
R400X mass storage expander
A Digital enclosure used for mass storage expansion.
RAID
Redundant array of inexpensive disks. A technique that organizes disk data to
improve performance and reliability. RAID has three attributes:
1. It is a set of physical disks viewed by the user as a single logical device.
2. The user's data is distributed across the physical set of drives in a defined
manner.
3. Redundant disk capacity is added so that the user's data can be recovered
even if a drive fails.
Contrast with striping.
read data wrapping
Memory feature that reduces apparent memory latency by allowing octawords
within a selected hexword block to be accessed in reverse order.
Glossary–16