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From: dyer@atari.UUcp (Landon Dyer)
Newsgroups: net.arch,net.micro.mac,net.micro.68k
Subject: Re: Bad Devices (was Re: timing loops)
Message-ID: <122@atari.UUcp>
Date: Wed, 26-Feb-86 19:37:32 EST
Article-I.D.: atari.122
Posted: Wed Feb 26 19:37:32 1986
Date-Received: Sat, 1-Mar-86 03:34:55 EST
References: <156@motatl.UUCP> <530@hoptoad.uucp> <6780@boring.UUCP> <144@sfsup.UUCP>
Organization: Atari Corp., Sunnyvale CA
Lines: 34
Xref: watmath net.arch:2648 net.micro.mac:4893 net.micro.68k:1525
Summary: Extra hardware *costs money*

In article <144@sfsup.UUCP>, mjs@sfsup.UUCP (M.J.Shannon) writes:
> As a kernel hacker, I would maintain that a device that requires a
> certain latency and neither rejects further commands nor signals an
> iterrupt until it's ready is a botch.  Why patch software when the
> hardware CAN do it right?  Software is not the answer to hardware
> designer ineptitude.  Even if it has to be done at the board level,
> the proper choice is to add the hardware to disable access to the
> device until its latency period is over.

That is, of course, unless the cost of hardware is a concern.  Software
is usually a one-time cost in a device driver for a personal computer,
whereas the hardware continues to cost money, machine after machine.
Given a part with bugs that is half the cost of a similar part,
without bugs, I would take the first part any day, for a "mass" market
computer.

Does anyone remember the Atari VCS (2600)?  It was a 6507 with 128 bytes
of RAM, a *sleazy* video chip, and a PIA.  Something like 18 million
of them were sold.  By all accounts it was one of the *worst* machines
to program ever devised by man.  Lines of video were generated by
counting cycles on the scanline and twiddling bits in the hardware
at just the /right/ clock on the screen.

Obviously a VCS is not a $10,000 Unix(tm) engine, but "pretty" hardware
may still cost money.  It is up to the marketplace to determine whether
or not it is worth it.  It wasn't worth it in the VCS, and it may not
be worth it in your Unix(tm) box.

And ... c'mon!  Surely you can write a piece of assembly language
that is g'teed to take 3us of processor time.  There are already
worse processor dependencies in the kernel and device drivers.


-Landon