Soul of a New Machine by Tracy Kidder - Page 1
Forum section: electronics / general

author: woodchips
author_rank: Frequent Contributor
timestamp: April 25, 2016, 09:09:30 am
content: This has been prompted by posting in the thread about old electronics shops in the UK.This is a story about the development of the 32 bit Eclipse computer by Data General, dates from the early 1980's.I read it then, and thought it was a real good book, but just re-read it and now not so sure. They seemed to design the computer by scattering chips on a PCB and then trying to get them to work? When I started electronics in 1971 I bought a dual channel Solartron CD1212 scope, equivalent to the 545. This cost me 8 weeks wages. But I quickly discovered that you had to design the circuit to stand any chance of it ever working. A 6800 based computer using a Baudot coded teleprinter as output. This required a hardware converter from 8 bit ASCII to 5 bit Baudot. Trying to find all the design details for it to recreate it at the moment.From then on the first thing was a pencil and some squared paper, lots and lots of timing diagrams. But it seemed to be successful, nothing I designed needed redesign to work. There were learning curves such as skew timing through CMOS parts, that the 373 really did need data hold time. But nothing like what was described in the Kidder book.I remember being given a couple of supposed designs for data buffers. The design consisted of some SRAM with a load of PALs around them. I never did understand why PALs were better than a few 161 counters. The 161s were fully described in data books, the PALs required me to design, test and document them.I reckon I learnt more from that scope about digital design than I was ever taught at university, basically nothing.There are frequent beginner requests about what to do, what to buy, to learn electronics. A handful of CMOS or TTL parts and a scope and make something, and also understand why it works. It may be old hat now but it is real, simulating a gate array doesn't seem to have the same reality about it. But, I still prefer a flickery analogue scope to a digital one, but my work is more fixing old computers and similar rather than 1GHz networks so possibly of no interest at all.What is other engineers' experience? How did/do you design?

author: Tomorokoshi
author_rank: Super Contributor
timestamp: April 25, 2016, 04:07:16 pm
content: While I read the book once a long time ago, interesting for me is the connection that my dad used a Data General Eclipse to do work back at that time:https://en.wikipedia.org/wiki/Data_General_EclipseThere was also a DG Nova in the lab:https://en.wikipedia.org/wiki/Data_General_NovaData and control were run through a couple HP terminals. All very impressive at the time, and very impressing for how a computer should look.

author: TimFox
author_rank: Super Contributor
timestamp: April 25, 2016, 05:41:13 pm
content: I still remember the bit where they named a specific logic line "not yet" on the schematic.

author: klunkerbus
author_rank: Unknown
timestamp: April 25, 2016, 06:22:19 pm
content: Great book. I used to encourage new engineers to read it. In part so that they could get a feeling for what it can be like to be on a product team, and in part to show them how every project they'll work on will build memories that will be with them for their career.I never had the luxury of computer analysis tools, so design involved hand drawn bubble diagrams for state machines and min/max timing diagrams for logic designs. Projects often also used peer review (to leverage the lessons learned from everyone else at the review) and prototyping (since paper analysis can only reveal so much).Projects that struggled in the long run were typically the ones where the designer cut corners on process because he felt he knew enough to do so, or were driven by program managers that "couldn't afford" the peer review or prototyping costs.

author: SeanB
author_rank: Super Contributor
timestamp: April 25, 2016, 06:35:48 pm
content: Major reason to go to PAL arrays was that you saved both board space, as you could jam around 15 TTL MSI chips into the PAL, getting a lot of real estate back, but you also got a lot lower propagation delay as there were no output stages and traces to drive, giving you around 30ns of improvement, which allowed a few things. You could use a higher speed clock, where a 1MHz increase was a major speed step, or you could use slower RAM and ROM, which was a major cost cut.As well the logic being in a single block meant you could fix any bugs simply by changing the map in the chip, rather than cutting traces and adding bodge wires on the production run of boards. Also allowed upgrading to say larger memories, simply by putting them in place of the smaller ones ( for older DRAM under 64K) or to increase ROM space if your design ran out of ROM, or to split the RAM/ROM on non chip based splits.As a bonus the black blob with a part number and only that, with the fuse bits blown so you could not read it, meant reverse engineering a design was more difficult.

author: klunkerbus
author_rank: Unknown
timestamp: April 25, 2016, 07:09:37 pm
content: Yeah, PALs were a great way to compartmentalize a design so that circuit board layout/fab could continue while the details of the logic were still soft. Use of combinatorial logic was something scrutinized in our peer reviews. Designers were often "encouraged" to replace discrete gates with PALs sprinkled throughout the board. I remember some large boards with little if any discrete gate chips involved.Of course, our designs were for pretty particular test or command & control equipment with only slight concern for material or manufacturing costs.

author: German_EE
author_rank: Super Contributor
timestamp: April 25, 2016, 07:53:42 pm
content: This book is the reason why I changed career into Electrical Engineering / Electronics.

author: rdl
author_rank: Super Contributor
timestamp: April 25, 2016, 08:11:31 pm
content: Excellent and memorable book. I bought it when it first came out in paperback. It's been at least 20 years since I last read it, but I still recall many parts clearly. I probably ought to figure out which box it's stored in and read it again.Quote

author: JoeN
author_rank: Frequent Contributor
timestamp: April 25, 2016, 09:19:20 pm
content: Interesting. Just reading Troubleshooting Analog Electronics by Pease now and that book gets a mention for a troubleshooting technique done by a manager in the book (essentially fonzieing a board to show an intermittent connection caused by a bad socket)

author: woodchips
author_rank: Frequent Contributor
timestamp: April 26, 2016, 08:15:17 am
content: Thanks for the posts.Yes, I remember the 'not yet' signal. But my point is that if they had spent the days actually designing the thing in the first place then they wouldn't have to spend them hunting for the problem. The difference is, that by designing it, you know exactly how it works and there are no errors left, by poking and hoping you have no idea if one or a million errors are left. The great thing about a synchronous machine is that at every clock tick the signals are stationary, there are no race conditions.PALs are wonderful, but still don't see the point in replacing two 161 counters with a 22V10. For random logic a PAL is wonderful, for tick tock jelly bean replacement they are a waste of time. Not really any saving in board space, certainly no saving in build cost (both part cost and programming time) and makes the sucker who might have to repair it job thousands of times easier.

author: tggzzz
author_rank: Super Contributor
timestamp: April 26, 2016, 08:52:44 am
content: Quote from: rdl on April 25, 2016, 08:11:31 pmCuriously that's the only quote from the book I remember. I didn't like the book because it never got inside the psyche of the people involved and felt entirely, um, soulless.I much preferred Robert X Cringely's "Accidental Empires".And yes, i was doing electronics and software in periods covered by the books.

author: rrinker
author_rank: Super Contributor
timestamp: April 26, 2016, 12:29:11 pm
content: I was wondering if someone else was going to bring it up. I'm pretty sure I've read "Soul of a New Machine" but the fact that I have to think about it at all means it wasn't the least bit memorable. "Accidental Empires" on the other hand... It could be because I used to love reading the Cringley column when InfoWorld was a print rag.

author: tggzzz
author_rank: Super Contributor
timestamp: April 26, 2016, 03:54:26 pm
content: Quote from: rrinker on April 26, 2016, 12:29:11 pmIt is still worth reading.

author: woodchips
author_rank: Frequent Contributor
timestamp: April 26, 2016, 06:55:51 pm
content: Don't think I have heard of Accidental Empires, what is it about?Another era book is The Cuckoos' Egg by Cliff Stoll, wonderful read.

author: tggzzz
author_rank: Super Contributor
timestamp: April 26, 2016, 10:49:54 pm
content: Quote from: woodchips on April 26, 2016, 06:55:51 pmAmazon is your friend.

author: rfeecs
author_rank: Frequent Contributor
timestamp: April 27, 2016, 01:03:22 am
content: Apparently the documentary Triumph of the Nerds is based on the book Accidental Empires:https://en.wikipedia.org/wiki/Triumph_of_the_NerdsIf you search for Triumph of the Nerds, there are full videos on YouTube and elsewhere.