"Real" speed of AT bus (MB/sec)?

Eric Gisin eric at MKS.COM
Wed Sep 13 09:18:10 AEST 1989

In article <22080 at cup.portal.com>, cliffhanger at cup.portal.com (Cliff C Heyer) writes:
< I'm having difficulty getting
< the specifications of the AT bus
< strait.
< What is the speed of the AT bus
< in MBytes/sec? (Thats 
< millions of 8-bit bytes per second).
< I know it's rated at 8MHz, but does
< ...

The original AT had a 6MHz processor.
Each bus cycle takes 3 to 10 processor clock cycles.
The cycle time for 16-bit operations is 0.5 usec, with 4MB/sec bandwidth.
The cycle time for 8-bit operations is 1 usec, with 1MB/sec.
The cycle time for DMA is 1.66 usec, with 1.2MB/sec (16 bit) or 0.6MB/sec (8 bit)

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