 | Level: Intermediate Clive "Max" Maxfield (max@diycalculator.com), Author, Freelance
03 Oct 2006 Imagine a computer formed from a mixture of technologies ranging from relays to fluidic logic. Now imagine being able to create a single piece of such a computer (perhaps as small as a single word of memory) in the technology of your choice, and then using the Internet to run your masterpiece in conjunction with other portions of the system created by contributors located around the world! Author Clive (Max) Maxfield explains the creation of just such a computing engine and how you can be involved.
Welcome to the first in a series of articles describing the creation of
a computing engine called The Heath Robinson Rube Goldberg (HRRG)
Multifarious Technology Computer. This machine will be built
using a variety of implementation technologies, including (but not
limited to) relays, vacuum tubes, transistors, and simple integrated
circuits -- also mechanical, magnetic, pneumatic, and fluidic logic
-- and possibly some even more esoteric technologies.
In case you were wondering, this contraption (affectionately known as
"The Beast")
is named after British cartoonist and illustrator William Heath Robinson
(1872-1944) and his American counterpart Reuben Lucius Goldberg
(1883-1970). Robinson and Goldberg were both famous for creating
illustrations of machines that were intended to perform relatively
simple tasks, but whose implementations were incredibly complex such
that they performed their tasks in exceedingly convoluted and indirect ways.
As you will come to see, it's probably safe to say that Heath and Rube
would have been proud of us! In fact, this is such a multilayered
project with so many diverse aspects, that it's easy to become lost in a
maze of possibilities, so please bear with me while I explain how this
all came to be and -- more importantly -- how anybody
(including you) will be able to play a part in the creation of The Beast.
As a starting point, glance at Figure 1 below. This is a relay computer,
created fairly recently by Professor Harry Porter III (standing next to
the machine in the photograph). Professor Porter is a lecturer at Portland
State University in the USA. You can discover more about Harry's
computer by visiting his Web site, which provides photos and videos along
with audio of the relays clattering away (see Resources for
more details).
Figure 1. Professor Harry Porter's relay computer (courtesy Harry
Porter)
Doesn't this look amazing? Wouldn't you like to have one? Well, this is
what sparked the HRRG project. I had long planned on creating a
relay-based computer of my very own, but once I saw Harry's magnificent
creation, there didn't seem to be much point because he'd already done
such a fine job.
And then I started thinking -- imagine a series of cabinets like Harry's
mounted around the walls of a large room. In the case of The Beast,
however, the contents of each cabinet will be implemented using a
different technology. Take the system clock, for example; this could be
formed from a cabinet containing an antique clock. The swinging of the
pendulum could be detected and used to provide the main system clock signal.
Alternatively, consider the famous old black-and-white horror film with
the mad scientist crying: "It's alive, it's alive!" In the
background, you may recall, there was a "Jacob's Ladder" formed from two
vertical metal electrodes with a series of electric arcs buzzing their way
from bottom to top.
Figure 2. An example home-made Jacob's Ladder
One of these could form the system clock cabinet; a
photo-detector could detect the arcs, where alternate arcs would represent
"tick" and "tock" signals -- following a power-on-reset (or a hard or soft
reset), the first arc will be taken to be a tick of the clock. (Find home-built
Jacob's Ladders -- along with many other interesting items -- on Mike Harrison's "Electric Stuff" Web site; see Resources).
The more one thinks about this, the more fun it becomes. Over the last
few months, numerous people have offered ideas such as using relay-based
memories from old jukeboxes or mechanical memories from old church
organs (these suggestions are gathered in an ever-evolving paper on the
HRRG project -- see Resources).
In fact, the memory and input/output (I/O) cabinets provide a simple
starting point from whence you can really let your imaginations soar.
Consider a cabinet containing a number of eight-bit output ports, for
example. Each of the bits could be represented by a servo-controlled
puppet: logic 0 and 1 values could cause the puppets to wave small yellow
and blue flags, respectively.
Alternatively, consider a memory cabinet employing some form of
pneumatic system that uses a ping-pong ball and two adjacent plastic
cone-shaped receptacles to represent each bit. A ball in its associated
left-hand receptacle could represent a logic 0, while the right-hand
receptacle could represent a logic 1 (or vice versa) as illustrated in Figure 3.
Figure 3. An eight-bit word implemented in a pneumatic memory
cabinet
In this case, when the system writes an eight-bit byte of data to one of
these memory locations, the pneumatics could "puff" the ping-pong balls
associated with that byte into their appropriate receptacles. The value in a memory location could be read
back again in a number of ways. For example, the ping-pong balls could be sprayed with
conductive metallic paint, and each non-conducting plastic cone could
have two bare conducting wires inside it. These wires (which, for
simplicity's sake, are not shown in Figure 3) would be close to each
other, but not touching. When a ball is inside a cone, it will short the
wires and complete that circuit. Thus, when the system reads a byte from
one of these memory locations, it would actually be determining the
location of the conductive balls.
How exciting! The only problem is that actually creating an entire
computer system as a mixture of different implementation technologies
from the ground up would be an incredibly time-consuming and
resource-intensive project to be undertaken by a single person,
organization, or academic institution. What is required is a cunning
solution... which brings us to the point of this article series.
When virtual and physical worlds collide
Before leaping into the fray, you should know that a number of
folks are involved in various aspects of this project; you can find out more
by visiting the "Who is to Blame" Web page described in Resources.
One key consideration is that anyone should be able to get into the game
and share in the fun, especially interested individuals and young people
at high school and college. As I previously noted, however, building
the entire machine would be a tremendous undertaking. On the other hand,
constructing a single cabinet containing (for example) only a few memory
locations would be a much simpler task.
Thus, the idea is to split the HRRG computer into a number of
well-defined functions. For reasons that should be obvious after seeing
Harry's computer at the beginning of this article, these functional
units are often referred to as "cabinets." In the case of memory (ROM
and RAM) and input/output (I/O) ports, the system can have as many
cabinets as one might wish, where each of these cabinets will have a
range of memory addresses associated with it. Of course, a key element
in this project is defining the interface and the protocol that the
various physical cabinets will use to communicate with each other and
with the outside world.
The next task will be to create a program called "The HRRG Emulator"
that will run on an IBM-compatible PC.
Amongst many other things, this emulator will include virtual
representations of the default cabinets (you will be able to add your
own virtual cabinets -- including nice graphical interfaces --
as you wish). As soon as it's finished, this emulator (and an associated
assembler) will be made freely available. This means that you will be
able to immediately create a program in the HRRG's simple assembly
language, assemble it, and run it on the emulator.
If you subsequently decide to create a physical version of any of the
cabinets, you can do so in the technology of your choice. By means of a
USB port, you can then connect this physical cabinet to your PC, and
the physical cabinet will run in conjunction with the virtual cabinets
running in the emulator. As you create more and more physical cabinets,
these will replace their virtual counterparts, until you eventually have
the entire HRRG implemented in the physical domain.
But wait, there's more, because the emulator will use the Internet to
support both virtual and physical units located around the world. This
means that if you create a relay-based ALU cabinet located in America,
for example, you will be able to run your cabinet with a physical memory
cabinet implemented in fluidic logic located in say, Australia, with
other physical cabinets located in other countries, and with any
"missing" cabinets running in the virtual world.
The mind boggles!
There are so many ramifications to this that it makes your head spin.
Take the Central Processing Unit (CPU) to be used as a basis for the
HRRG, for example. As it happens, a small calculator circuit board
featuring an FPGA-based version of this CPU is currently under
development (see the "Who is to Blame" Web page in Resources). Eventually, it might be possible for you to build, say, an
Arithmetic Logic Unit (ALU) cabinet out of relays, mount it on your
office wall, and connect it into this calculator circuit board, where it
would replace the ALU running in the FPGA.
You've probably got enough to be thinking about for now. Part 2 of this
series will consider the various functional units forming "The Beast,"
including discussions on the CPU to be used along with any decisions
with regard to splitting this CPU into functional units (cabinets). Part
3 will introduce the emulator software, and Part 4 -- well, you'll just
have to wait and see...
Resources Learn
- Get an RSS feed for this series or subscribe to the zone newsletter IBM microNews and be notified each time a new installment is published. (Find out more about RSS feeds of developerWorks content; find out more about IBM microNews.)
-
See all of the articles in this
series to date.
-
Harry Porter's Web site describes his relay-based
computer in detail.
-
Find home-built Jacob's Ladders -- along with many other interesting items -- on Mike Harrison's Electric Stuff Web site.
- Find numerous suggestions for "The Beast" on the HRRG
Project Web page.
-
The various folks involved in the HRRG project in one way or another are
introduced in this Who is to blame? Web page.
- Get the book, How Computers Do Math, which features the same CPU that
will be used to form the basis for the HRRG, from Amazon.com.
- Download a virtual version of the same CPU that will be used to form the basis for
the HRRG for free from the "Downloads" page on the DIY Calculator
Web site.
-
The "More Cool Stuff" page on the DIY Calculator Web site contains a
treasure trove of topics, including A
History of Calculators and Computers, A
Timeline of Calculators, Computers, and Other Stuff, The
Computing Universe, Rounding Algorithms 101, and a rather interesting paper
on Color Vision.
-
One of the last bastions of mechanical computing was the mercury
delay line memory (this link is to an operations manual for a
representative example of the technology).
-
Hydraulic computing is a highly visual way of simulating certain sorts of
problems. MONIAC is a hydraulic computer that simulates an economy. By adding ink to the system
at one point, you can observe how a droplet of money added to any point in
an economy will gradually spread to the entire system.
-
The
IBM Semiconductor Solutions Technical Library
hosts a wealth of information -- from
specifications and user manuals to product briefs and errata and much more.
-
Keep abreast of all the Power Architecture-related
news that's fit to print: subscribe to IBM microNews.
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About the author | 
| | Clive (Max) Maxfield is the author/co-author of a number of books,
including Bebop to the Boolean Boogie (An Unconventional Guide to
Electronics) and How Computers Do Math, featuring the pedagogical and
phantasmagorical virtual DIY Calculator.
In addition to being a hero, trendsetter, and leader of fashion, Max is
widely regarded as being an expert in all aspects of computing and
electronics (at least by his mother). Max was once referred to as "an
industry notable" and a "semiconductor design expert" by someone famous
who wasn't prompted, coerced, or remunerated in any way.
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