PSN-L Email List Message
Subject: Re: Basic Programming Help desired?
From: Canie canie@...........
Date: Mon, 05 May 2008 15:12:38 -0700
Yes - size of the data record can have such an effect.. all these
little things that you'de wish the Microsoft engineers would know..
We always tried to do record sizes (of file definition sizes) of 64,
256, 512, 1024 bytes..for that reason - the disk writes would be faster..
And for some reason division is slower that multiplication.. so for
certain things, rather than divide, we'de figure out how to
multiply.. also these things can be compiler dependant I assume..
At 12:09 PM 5/5/2008, you wrote:
>Roger Wilco Canie;
>I have found when dealing with the disk
>it matters how many bytes you can deal with
>in a single instruction/operation and that those bytes
>match the sector sizes on the disk itself.
>I think that one sector can be entirely
>written in a single write operation
>but if you use odd sizes it slows things down.
>Possibly the way the compiler does things
>is also important like DMA or Interrupt
>type programming. DMA between ram and disk
>is most probably the best way to go for a
>stable machine. But this would require
>assembly programming of a custom nature
>and Id have to go back to school to
>be able to do this.
>The sector sizes vary according to
>where you are on the disk and what the
>format type happens to be.
>It seems to me that powers of two relating to
>512 bytes is possible the right thing to do.
>Someone has all the answers but finding
>a willing person to share such knowledge
>is very difficult for myself. Such expert people are
>typically too sensitive about sharing knowledge.
>They are capitalists with eyes that see only money
>and not true amateurs seeking and sharing knowledge.
>Thanks for your input.
>DMA = Direct memory access where you wind up the hard
>drive ( or whatever ) and it goes and gets its own data from ram
>by itself using the transfer times between machine (CPU) cycles.
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