Let's develop an open-source media archive standard

[Steve Thatcher]

no mention of age and unfortunately I am old enough to have worked on and designed predicatbale systems...

-----Original Message-----
From: "Dwight K. Elvey" <dwight.elvey at amd.com>
Sent: Aug 12, 2004 6:41 PM
To: cctalk at classiccmp.org
Subject: Re: Let's develop an open-source media archive standard

Hi
 I was more referring to a modern PC than specific
older hardware. The issue with doing direct I/O
is the it needs to be predictable and on time.
Most modern machines can no longer to that reliably
without using DMA. They have too may other things
that they are expected to do simultaneously. Also
because of multiple levels of caching, real-time
predictability is not practical.
 In the N*, they dedicate a predictable processor
to do just the disk I/O and nothing else.
Dwight


>From: "Steve Thatcher" <melamy at earthlink.net>
>
>I seem to recall that my slow old N* Horizon was doing dd at 4mhz with no dma - 
in fact it was polled I/O because their wait for I/O available kept locking up 
so I modified it.
>
>best regards, Steve Thatcher
>
>-----Original Message-----
>From: Fred Cisin <cisin at xenosoft.com>
>Sent: Aug 12, 2004 5:12 PM
>To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>Subject: Re: Let's develop an open-source media archive standard
>
>On Thu, 12 Aug 2004, Dwight K. Elvey wrote:
>> Hi Jules
>>  Here is what I've found. It is a disk drive emulator.
>> Unless a PC is DMA driven, bit banging a floppy is not practical.
>
>Disk I/O without DMA is not practical.  But it IS possible.
>Consider the PCJr and Tandy 1000, both of which do disk I/O
>without DMA on 4.77MHz? machines.
>
>
>