
IBM32NPCXX1EPABBE66
IBM Processor for Network Resources
Preliminary
Ordering Information
Page 2 of 706
pnr261_1intro.fm.06
August 14, 2000
1.3 Ordering Information
1.4 Conventions and Notation
In most of this document, bit notation is non-IBM, meaning that bits and bytes are numbered in descending
order from left to right. Thus, for a four-byte word, bit 31 is the most significant bit and bit 0 is the least signifi-
cant bit.
Exception:
In section
3.19 Embedded PowerPC Processor (COBRA)
on page 469, IBM bit notation is used,
meaning that for a four-byte word, bit 0 is the most significant bit and bit 31 is the least significant bit.
The internal addressing view of the PNR registers and memory is big endian. In most cases, a system will
wire its PCI bus interface to make the register view transparent, that is, the most significant bit in this specifi-
cation will be the most significant bit in the register. If registers are read and written 32 bits at a time (which is
the only way to access many of the registers), the endian-ness should not be a programming issue with
respect to the registers.
The PNR DMA controller can transfer data in either big endian or little endian mode. See
3.2 General Pur-
pose DMA (GPDMA)
on page 73 for details.
Register access conventions:
Read/Write - bits of the register can be read or written.
Read Only - bits of the register can only be read. Writes have no effect.
Clear/Set - if writing to the base address of the register, writing a
‘
1
’
to a register bit causes the bit to be
cleared. If writing to the base address of the register+4, writing a
‘
1
’
to a register bit causes the bit to be
set. Either address can be used to read the register.
Numeric notation is as follows:
Hexadecimal values are preceded by x and enclosed in single quotation marks. For example: x
’
0B00
’
.
For individual registers, Address values are hexadecimal without any special markings and may use an X
as a placeholder. For example, XXXX 1C3C.
Binary values in text are either spelled out (zero and one) or appear in single quotation marks.
For example:
‘
1010
’
.
Binary values in the Default and Description columns of the register sections are often isolated from text
as in this example:
0
No action on read access
1
Auto-reset interrupt request register upon read access
Part Number
Description
IBM32NPCXX1EPABBE66
IBM Processor for Network Resources version 2.61
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