Raspberry Pi 400 vs ZX Spectrum
The release of the Raspberry Pi 400 personal computer reminded me of a wildly popular home computer that was launched in a similar computer-in-a-keyboard format almost 40 years ago: the Sinclair Research ZX Spectrum. I decided to compare the two, following the steps of an earlier comparison I performed between the 2015 Rapsberry Pi Zero and the 1957 Elliott 405.
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The titanic battle between big iron and microprocessors
I'm a child of a microprocessor age. I learned to program on computers powered by a variety of microprocessors starting with the 4-bit SC43177/SC43178 pair powering a Sharp PC-1211, continuing with the 8-bit Zilog Z80 on the TRS-80, the Zenith Z-89, and the Sinclair ZX81 computers, and graduating to 16-bit processors: the Texas Instruments TMS9900 powering its manufacturer's TI-99/4A home computer and finally Intel's 8088 on an IBM Portable (16kg) Personal Computer. At the university I encountered an IBM System/370 4331/2 mainframe, which I regarded with outer contempt. It seemed to me like a dinosaur: slow and unwieldy, lacking interactivity, color, and graphics. I couldn't fathom why businesses were using such monsters. I now understand that I was watching an amazing race between the sprightly but woefully simplistic microprocessors and the powerful but slow-moving mainframes.
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Contact tracing via smartphone apps has been widely touted as an important way to control and limit the spread of the COVID-19 epidemic. However, basing contact-tracing on phone apps has several limitations. Here are instructions for constructing a contact tracing device prototype with a Raspberry Pi Zero-W. The constructed device is compatible with the Apple/Google Bluetooth contact tracing specification. It runs the Epidose software, which is based on the DP3T "unlinkable" design.
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Computer vs Human 0-1
Earlier today the Athens State Orchestra played the Symphony No. 3 in C minor, Op. 78 by Camille Saint-Saens, which is also known as the Organ Symphony. The French organist and composer Thierry Escaich was supposed to play the organ. There was a slight delay at the beginning: a lady appeared on stage and explained that there were technical problems with the organ's "brain".
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The Computer Tube
I've been reading the book ENIAC in Action,
which details the fascinating ten-year history of the first general-purpose
programmable electronic computer.
In it I found a reference to 7AK7, the so-called computer tube,
which improved the reliability of tube computers.
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Raspberry Pi vs USB vs Mac Audio
The audio hardware of Raspberry Pi is
to produce relatively poor sound quality.
I bought a cheap USB sound card to try as an alternative.
Here is what I found.
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Raspberry Pi Zero vs Elliott 405
Raspberry Pi Zero
juxtaposed in front of the Norwich City Council Treasurer's Department building,
where the delivery of the Elliott 405 computer was photographed in 1957.
Here is how the two computers compare.
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How to make a MacBook Kensington Lock Adapter
Apple, in its infinite wisdom, has not included a Kensington lock
slot in the current model of the MacBook Pro computer.
Given the computer's price, desirability, and
the fact that three people I know have had theirs stolen,
I decided to build an improvised adapter that would allow me
attach a Kensington lock to the computer.
I realize, that the security offered by such a contraption is what
calls an "advisory lock",
for Kensington locks can be easily picked or pried away.
However, I think it might deter a casual thief who would
snatch the laptop you've left unattended for a couple
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The virtual machine (VM) is the most dazzling comeback in information technology. IBM implemented a VM platform architecture in the late 1960s in its CP/CMS operating system. The company’s goal was to provide the time-sharing capabilities that its batch-oriented System/360 lacked. Thus a simple control program (CP) created a VM environment where multiple instances of the single-user CMS operating system could run in parallel. Thirty years later, virtualization was rediscovered when companies like VMware found ways to virtualize the less accommodating Intel x86 processor architecture. The popularity of Intel’s platform and the huge amount of software running on it made virtualization an attractive proposition, spawning within a decade tens of proprietary and open source virtualization platforms.
Continue reading "Virtualize Me"
Research Proposal Becomes Reality
Eight years ago I submitted a research proposal for developing a
tablet-based game platform for toddlers.
Although the proposal was not accepted for funding,
it's nice to see the idea becoming a reality through the
unveiling of the Toys 'R' Us $150 Tabeo tablet for kids.
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Using the HP 4470c Scanner Under Windows 7
Hewlett Packard nor
Microsoft Windows 7
offer native support for my HP 4470c scanner.
Throwing a working scanner away to buy a new one only because some
software was missing seemed like a waste,
so I looked for an alternative solution.
This is how I made it work using SANE,
an open source framework for scanners.
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This column is about a tool we no longer have: the continuous rise of the CPU clock frequency. We were enjoying this trend for decades, but in the past few years, progress stalled. CPUs are no longer getting faster because their makers can’t handle the heat of faster-switching transistors. Furthermore, increasing the CPU’s sophistication to execute our instructions more cleverly has hit the law of diminishing returns. Consequently, CPU manufacturers now package the constantly increasing number of transistors they can fit onto a chip into multiple cores—processing elements—and then ask us developers to put the cores to good use.
Continue reading "Faking it"
Ten Lessons I Learned from Fixing my Laptop's Motherboard
A month ago I managed to break my laptop, by reversing the polarity of
a universal power supply.
The repair shop diagnosed the problem as a failed motherboard,
and asked for €659 to replace it.
I found the price preposterous and the notion of throwing away a motherboard
for a single failed component ecologically unsound.
Here is how I fixed the laptop on my own, and what I learned in the process.
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HP-200LX Remote Control Hacks
All my friends know that for the past 15 years I've been semi-attached
(recently updated to a 200LX)
for my personal information management and many other tasks.
The device is extremely versatile, sturdy, and flexible.
Amazingly, after so many years of hard daily use, I still find new
applications for it.
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Revisiting the Antikythera Mechanism Emulator
Over the past few weeks I updated the
Antikythera mechanism emulator
I built in 2007.
I was preparing for an invited talk on the subject, which I'll give at the
2009 USENIX Annual Technical Conference,
and for this I wanted to include in the emulator the new findings
recently published in Nature.
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The Information Train
The Information Train is a scientific
experiment that I presented at the
Wizards of Science 2009 contest over the past weekend.
The entry demonstrates how computers communicate with each other by
setting up a network in which a model train transfers a picture's pixels
from one computer to the other.
You can find
a video of the experiment
on YouTube, and, if you're interested, you can also download
the corresponding software and schematics from
this web page.
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No Blinkelichten, Please
A computer's flashing lights used to fascinate me.
They showed me it was alive and offered me a glimpse on
They also epitomized the hacker culture of the famous "Blinkenlichten" sign.
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LTO Tape Drive Compression Considered Harmful
I used to think that tape drive compression was a silly marketing trick
used by manufacturers to inflate the advertised capacity of their tape drives.
Apparently it is worse than that.
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Landscape vs Portrait Monitors
Laptop monitors keep getting wider and wider.
What I would really like would be for them to get higher.
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The Capacitor Plague Hits a Baby Monitor
Good baby monitors are hard to come by.
Many tend to be oversensitive, others switch from squelch mode to
transmission with a loud hiss that is more irritating than a baby's
We were very satisfied with a Tomy Walkabout Digital
1998 baby monitor, until the day it started emitting a squeaking
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(Not) Hacking the Digipass Go 3 OTP Dongle
My bank moved to two factor authentication solution, and thus required me to purchase
from them a Digipass Go 3 dongle in order to authenticate my transactions.
To register my dongle I keyed-in a five-digit code they gave me,
and also the key's serial number appearing on its back.
Given that Go 3 utilizes an
open authentication framework,
and a published algorithm
for generating the one time password (OTP), could I utilize the key and the
numbers I keyed in, for using the key in my own applications, of for cloning
the dongle in my mobile phone or palmtop?
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I first admired this ingenious method of locking a car in
Mr. Bean series.
A few days ago I saw it in real life.
Continue reading "Boot Lock"
Let's start the new year with a retrospective look at hardware advances.
I've ordered some older and current hard disks that were lying around
We're taking for granted the increases in disk size, but also
impressive is the reduction in size of the control electronics.
Continue reading "Disappearing Hardware"
MIT's $100 Laptop
The MIT Media Lab is working on a research initiative to develop
a $100 laptop.
This will be distributed through governments to schools to
help the education of the world's students.
These are my notes from a talk
Director of Computing at the MIT Media Lab
gave on the subject, at an event organized by the
Netmode Laboratory .
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Hard Disk Failure
I tell everybody that the question is not whether your hard drive
will fail, but when it will fail.
My laptop's drive started emmitting a loud grinding sound last Saturday.
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Lack of Progress in Palm Applications
An article in slashdot
recently discussed the limitations in the current breed of Palm
I am glad somebody has pointed out the lack of progress in the palmtop market. My 12-year old HP-100LX is literally falling appart, yet I can not find a worthwhile replacement.
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