Menu
The ultimate DIY computer project
06 May 11 08:38 GMT
By Mark Ward
Technology correspondent, BBC News
Some people like to build their own
computers. A smaller number like to
modify them to boost the speed of
the processor and make them more
powerful.
Then there is an elite for whom building
a modern PC is mere tinkering. Instead,
they opt for the much more difficult task
of building their own microprocessor
from individual components.
They make it easier for themselves by
emulating the relatively low-powered
processors found in the first personal
computers.
That's a sensible step given that the
microprocessors inside a contemporary
PC have millions, if not billions, of
transistors on board. Wiring or
soldering those would take several
lifetimes.
Parts list
But that takes nothing away from the
complexity of building a processor from
parts. Even a simple one can take
months, often years, to put together.
One of the first to do a DIY processor
was Bill Buzbee who made one from
TTL logical chips, 74 of them in all.
Before microprocessors were invented,
early computers used scores,
sometimes hundreds of simple
integrated circuits wired together to
create a central processing unit. Such
systems are known as Transistor to
Transistor Logic (TTL)
"Back in the 70s when I first got
involved in computers and electronics,
TTL chips were what people used, so
that's what I turned to," said Mr
Buzbee.
Despite starting his working life as a
journalist, he became a programmer
and embarked on the task to firm up his
knowledge of how hardware worked.
"It started out to be a very small project
and it grew to something much more
elaborate," he said.
Help and advice came from the many
people who found his project blog, a
journal he used to organise his
thoughts about how to build the
processor and incorporate that into a
working computer.
"I have had a lot of help, most of it
unsolicited, from electrical engineers,"
he said.
Some of the parts for what would
become Magic-1 were bought
specifically for the job. But, true to the
DIY philosophy, many others were lying
around in Mr Buzbee's home.
Using store-bought and found
components, the design for the
machine evolved organically.
"It's not so much that I designed the
computer and got the parts for that," he
said. "I designed around what parts I
had."
As it turned out, building the processor
and its associated hardware was just
part of the challenge. The novel
machine needed feeding with software,
including a compiler and assembler, if it
was to do anything useful.
"The biggest part of the job by far was
all the software," he said. "The vast
majority of the time was doing that."
Was it time well spent?
"I learned a fantastic amount," he said,
"I came into it with a reasonably good
knowledge, but this opened up a lot of
areas that I did not have much
exposure to."
Mr Buzbee had the foresight to video
the first working test of Magic-1 and his
exclamation of "Outstanding!" as the
machine does what it is supposed to
sums up the project and its results.
Making machines
The trail blazed by Mr Buzbee has been
followed by many others.
Computer scientist Dr Harry Porter built
his 8-bit machine from relays -
electronic switches that are even
simpler than the transistors used in
Magic-1. Despite this, the machine has
all the bits you would expect to find in a
smaller processor.
Relays are also a good deal bigger than
transistors so the Relay Computer
occupies four large wooden cabinets
and makes a rhythmic clickety-clack
racket when its 8-bit might is being used
to crunch numbers.
One of the most recent homebrew
CPUs is the Big Mess o'Wires (BMOW)
made by Steve Chamberlin from a
whole lot of logic chips. Like many of
the other DIY processor folks, he
started small but. Over time, the design
and his ambitions for it grew.
"My goal was only to tinker around with
digital electronics projects of the sort I
remembered fondly from university
days," he said, adding that he expected
that once it was built he would program
and play with it via a terminal window
connection to a modern PC.
"After I got the basics working, though,
I kept revising my goals and adding
more and more external systems," he
said.
The finished BMOW has a keyboard,
VGA video, audio and is programmed
using Basic.
"BMOW grew into a stand-alone
computer system, independent of any
PC, and roughly similar in capabilities to
8-bit computers of the early 1980s," he
told the BBC.
The journey from bits to finished
computer taught him a huge amount
about how computers work and the
challenges that faced those early
computer makers.
"I feel I have a much better
appreciation for what it must have been
like when Steve Wozniak designed the
original Apple, or other homebrew
systems of the day," he said.
Related to this story:
The man who invented
the microprocessor (04
May 11 | Technology)
Recreating the era of 8-
bit computers (
Published with Blogger-droid v1.6.8
No comments:
Post a Comment