RTEMS on MCP750 and MTX-60x, for Eric Valette

Eric Norum eric.norum at usask.ca
Thu Nov 7 18:18:37 UTC 2002

On Thursday, November 7, 2002, at 12:02  PM, Chris Caudle wrote:

> On Thursday 07 November 2002 12:52 pm, gregory.menke at gsfc.nasa.gov 
> wrote:
>> - In registers.h, you lay out the HID0 bits as leftwards bit shifts,
>>   but the Motorola docs lay out the bits with LSB leftmost,
> If the Motorola docs are like the IBM docs, the leftmost is actually 
> MSB,
> but it it called bit 0.  LSB is then bit 31 (e.g. in a 32 bit 
> register).

Yes, the Motorola PPC documentation uses strictly correct notation for 
a Big-Endian machine -- significance decreases with increasing item 
numbers (bits in a byte, bytes in a word, etc).

For a great description of the issues involved see,

D. Cohen, "On Holy Wars and a Plea for Peace", IEEE Computer Magazine, 
Volume 14, Number 10, October 1981, pages 48-54.

Eric Norum <eric.norum at usask.ca>
Department of Electrical Engineering
University of Saskatchewan
Saskatoon, Canada.
Phone: (306) 966-5394   FAX:   (306) 966-5407

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