[rescue] A5000 questions...

Dave McGuire mcguire at neurotica.com
Wed Aug 6 23:19:40 CDT 2003


   Base sbus is 32 bits wide.  There are systems with 64 bit sbus.  I 
don't know which ones offhand, though.

        -Dave

On Wednesday, August 6, 2003, at 11:15 PM, H.H. wrote:
> errrrrrr....... isn't that 64 bits wide (8 bytes)?
>
>>
>>   Uhhhhhhhhh, NO.  Sbus is usually clocked at 25MHz and it's four 
>> bytes wide, making it about the equivalent in performance to baseline 
>> PCI.  The faster (33MHz) baseline PCI clock advantage is eaten up by 
>> the way sbus starts and stops transfers...with sbus, one transfer can 
>> start on the very next cycle after the last transfer ends, but with 
>> PCI there are intervening arbitration cycles.
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--
Dave McGuire                 "You don't have Vaseline in Canada?"
St. Petersburg, FL                     -Bill Bradford



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