Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!iuvax!watmath!mks!eric
From: eric@MKS.COM (Eric Gisin)
Newsgroups: comp.unix.i386
Subject: Re: "Real" speed of AT bus (MB/sec)?
Summary: from AT tech ref
Message-ID: <1609@mks.UUCP>
Date: 12 Sep 89 23:18:10 GMT
References: <22080@cup.portal.com>
Reply-To: eric@MKS.COM (Eric Gisin)
Lines: 17

In article <22080@cup.portal.com>, cliffhanger@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)