*BSD News Article 19466


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From: jmonroy@netcom.com (Jesus Monroy Jr)
Subject: Re: More annoyance on the DMA problem
Message-ID: <jmonroyCBp5Ks.CM3@netcom.com>
Followup-To: comp.os.os2.programmer,comp.os.linux,comp.os.mach,comp.os.minix,comp.periphs,comp.unix.bsd,comp.unix.pc-clone.32bit,comp.os.386bsd.development
Organization: NETCOM On-line Communication Services (408 241-9760 guest)
X-Newsreader: TIN [version 1.1 PL8]
References: <jmonroyCBoq14.Kz0@netcom.com>
Date: Fri, 13 Aug 1993 12:05:15 GMT
Lines: 42

 
>> From: rooij@bashful.isp.cft.philips.nl (Guido van Rooij)
>> Subject: Re: More annoyance on the DMA problem
>> Organization: Philips Communications & Processing Services, Eindhoven
>> Date: Fri, 13 Aug 1993 09:39:00 GMT
>>
>> jmonroy@netcom.com (Jesus Monroy Jr) writes:
>>
>> >
>> >        The new FDC driver is reading a 1.44 meg diskette in
>> >        about 1 minute 30 seconds.  There are 2880 sectors on
>> >        a diskette of this size.  2880 divided by 90 seconds
>> >        is 302 sectors per second.    66,287  divided by 302
>> is it? 2880/90=32
>>
        Correct.  The ultimate in miscalculations on my part.
        I have errored.  I am human.
 
        At times I must communicate with non-humans,
        this may not include yourself. As I have no evidence of this.
 
        Again, I have errored.
 
        OK...32 sectors per second.
 
        66,287 / 32 = 2071 refreshes per sector transfer.
 
        1 / 32 =    0.03125  second per sector transfer
 
        Gee! Thanks for the correction.
 
        This makes the new index 5.  The numbers match exactly.
 
        MY POINT IS THE LOWER HARMONIC OF THE DMA REFRESH
        COLLIDES WITH THE FDC TRANSFER.
 
 
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Jesus Monroy Jr                                          jmonroy@netcom.com
/386BSD/device-drivers /fd /qic /clock /documentation
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