25 Apr
2002
25 Apr
'02
8:20 a.m.
On Thu, 25 Apr 2002, Andy Holt wrote:
Digikey is not bad for small orders
-----Original Message-----
From: owner-classiccmp(a)classiccmp.org
[mailto:owner-classiccmp@classiccmp.org]On Behalf Of Allison
Sent: 25 April 2002 15:57
To: classiccmp(a)classiccmp.org
Subject: Re: .I.P. for D.I.Y.
From: Andy Holt <andyh(a)andyh-rayleigh.freeserve.co.uk>
When I was home-brewing computers about 20 years ago the modern components
of the time were
reasonably easy to obtain
reasonably stable for wire-wrap
easy to solder - or use in sockets
adequately documented (usually :-)
if programmable could be DIY programmed rather than needing an expensive
box
and almost everything worked from a simple 5v supply
Nowadays
You typically have to deal with distributors - little problem for the
experienced, but an obstacle to newcomers I'll agree - but perhaps the main reason is
that modern components are
almost impossible for the home builder ... and only the odd few
(Tony? :-)
Impossible? How? The edge speed of modern logic is so high that WW is
unlikely to work
You can lower the I/O slew rates on programmable parts
In fact even PCBs now need designing using UHF
techniques for the same
reason
Not all pcbs...
SMT devices - and almost everything nowadays is only
available as such -
are best handled with an expensive soldering station (and BGA devices need
even more expensive equiment).
A simple soldering iron and a hot air gun are adequate for much surface mount
assy...
Documentation - though nowadays typically easier to
obtain - is often
oversimplified.
Programming devices often needs (one or both of) expensive hardware or
extremely expensive software.
Software for at least Xilinx stuff is free...
You can download the configuration to a FPGA with nothing more than a parallel
port, or a few I/0 bits...
I stand by the "almost impossible" statement above.
Nonsense! Just people who don't want to bother trying...
The one main exception to this black picture is the single-chip flash
micro - such as the PIC family or the 8051 derivatives. But working with
these is more like computer programming than hardware design.
Peter Wallace
Generalizing on DIY/homebrewing is not good as
exceptions do abound.
Which is why I use terms like "almost impossible"
and "few" rather than
absolute statements.
Andy