RE: 264/TED/Plus4 Story

Yeah I don't actually know exactly  when it worked and then just tweaked
but back then it was common, and a chip team was measured, by how many
revs it took to get the chip functional enough to plug into a working
system.

It wasn't unusual to make some changes for producability and even things
like power consumption.  They would lay a small LCD temperature sensing
thing on the die and then review the hotspots, they found things like a
transistor acting as a 200ohm resister between power rails, etc.
Sometimes he Genrad guys would ask for a little more by way of
testability.

-----Original Message-----
From: owner-cbm-hackers@musoftware.de
[mailto:owner-cbm-hackers@musoftware.de] On Behalf Of Gerrit Heitsch
Sent: Thursday, October 27, 2011 2:59 PM
To: cbm-hackers@musoftware.de
Subject: Re: 264/TED/Plus4 Story

On 10/27/2011 08:44 PM, Bil Herd wrote:
> No it took that many revisions to get that chip WORKING. :)

Hm.. OK... The prototype board mentioned here has a 7360R4A on it, makes
me wonder how well that rev was working (and if it still does work).


> The kind of thing they fixed going from 6 to 7 dealt with things like
the
> white noise generator.  It was a 256 byte ring counter or similar and
the
> chip guys left the cells to power up in random states and would the
shift
> them round and round, the problem was that due to process and geometry,
> they weren't quite random and so the white noise had a recirculating
> pattern to it, on a good day it sounded like a motorboat, a bad day was
a
> motorboat in a hurricane.   So someone wrote a (Basic)program and
> generated a random number string and they hardcoded those as the
starting
> bits for the white noise bucket-brigade generator.

It still sounds kind of odd with a pattern to it though. Not quite what
I was expecting when reading 'white noise generator'. But at least it's
consistent.

Even after switching from 7360 to 8360 MOS needed two more revisions to
get the HMOS-II TED working as intended.

  Gerrit


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