see below, plz.
Dick
----- Original Message -----
From: "Tony Duell" <ard_at_p850ug1.demon.co.uk>
To: <classiccmp_at_classiccmp.org>
Sent: Saturday, November 03, 2001 11:34 AM
Subject: Re: CPU design at the gate level
> >
> > Well, if you have to repair a terminal with those adders, carry generators,
etc,
>
> Sure, or a minicomputer CPU, a control system, a machine tool, or
> whatever else uses them. Believe me, I don't like having to hunt around
> for a $1 part to fix a mutli-thousand-dollar (or pound) machine. I'd like
> to just go out and buy it.
>
> But, alas, the main market for ICs is not repairers. Nor is it
> homebrewers (for whom a board of TTL chips is often a lot easier to debug
> than an FPGA, and cheaper as well (a soldering iron is a lot cheaper than
> the PC [1] to run the FPGA design tools, even if the latter are free). I
> still believe it's educational to make at least one machine from MSI
> chips. And also to make one using FPGAs.
>
> [1] I am not sure of the current list price of a modern PC + monitor +
> Windows, but in the UK, you can get pre-packaged semi-proprietry machines
> for about \pounds 1000. And a bit more if you want soemthing that's
> reasonably standard and which you have some hope of being able to upgrade.
>
I just got an unsolicited email from a vendor in Texas that's asking $279 US for
what's really an eMachines "eTower-633" (with the trademark badge missing form
the front of the box) with a 15GB HDD, a DVD drive, 128MB RAM a 56KB modem, and
the usual stuff along with a mouse and keyboard. No monitor and no OS.
Shipping to anywhere in the continental U.S. is $35. A friend of mine bought
one for his own use, and I helped him fiddle with it, and convinced myself that
it's a good and solid enough machine. His hard disk failed and he had a
replacement within a week, so the usual warranty mechanisms are in place as
well.
>
> > in it, there's little you can do without them, aside, perhaps from building
a
> > daughterboard with a bunch of programmable parts, or at least one
significant
>
> Yes, I've had to do that...
>
> > one. The latter always produces the risk of not providing the races that
were
> > designed into the original circuit and therefore failing due to proper
design
> > practice.
>
> Alas all too true. A lot of the TTL-based stuff from the 1970s has some
> poor design practicies in it, but if it works, there's no reason to
> attempt to redesign it.
>
> -tony
>
>
Received on Sat Nov 03 2001 - 13:01:49 GMT