Date   : Sun, 12 Jun 2005 15:51:39 +0100
From   : Andrew Benham <adsb@...>
Subject: Re: Issue 4 BBC B's

Mike Tomlinson wrote:

> The Video ULA was also changed
> from a Ferranti chip requiring a heatsink to a VLSI unit, which didn't
> need a heatsink, at about the same time.

I'm really glad that semi-custom IC technology has moved on, because
"ULA" is a lousy piece of terminology.
It stands for "Uncommitted Logic Array", which is an accurate name until
the last few steps in the manufacturing process.  These steps take the
uncommitted "sea of gates" and, by adding an interconnect layer of metal
according to the specification of the customer, turn it into a custom IC.

Whilst uncommitted (which is the only time that it's actually a ULA) it
is of no use (it's rather like an unprogrammed ROM) - other than it has
the potential to become useful.

So, to the pedant, the terms "Video ULA" and "Serial ULA" are wrong - 
because the Logic Array can't be Uncommitted at this point - it's been
committed to a customer's specification.

-- 
Andrew Benham         adsb@...       
Southgate, London N14, United Kingdom

The gates in my computer are AND OR and NOT, not "Bill"