Making a soft-circuit input device for your computer

I’m intrigued by various uses for embedded processors, and so are my readers. I hadn’t seen this particular microcontroller board before, the “Teensy”, which is very similar to the Arduino, except that it is uses an ATMEL AVR chip with a direct support for USB. The link also points at a nifty interface to “soft circuit” elements, which probably has some nifty controller applications.

Make: Online : Making a soft-circuit input device for your computer.

Re-animating the PDP-11/70

A few years ago, Tom Duff and I each wrote an emulator for the PDP-1 so we could play the original version of Space Wars! I learned a lot about old computers in the week or so it took me to do, and I must admit that I’ve retained a fascination for old computers ever since. Tom mentioned that he has a front panel from an old PDP-11, and has talked about doing a project where he wires the front panel to a more modern machine running a PDP-11 emulator, which seemed like a cool idea. After all, modern computers just don’t have enough blinking lights. Here’s a link to a project which does precisely that using an inexpensive Zilog microcontroller over ethenet. It also includes some links to other similar and interesting projects. Check it out.

Re-animating the PDP-11/70

MacWorld Announcements

Well, Steve is still up there, but the big news (as yet unreflected on the Apple website) is the announcement of a new Intel based iMac. It will apparently come in the same sizes and prices as previous G5 iMacs, but will use Intel’s new CoreDuo processor that was plugged by Intel so heavily at CES last week.

There is also some nice improvements to their existing iLife suite, including the addition of the (somewhat predictably name) iWeb: a web authoring suite that includes the ability to create and publish rich media websites using premade Apple templates. Notable for podcasters, GarageBand will also include a Podcast Suite: a set of features designed to make the creation of podcasts simple and easy.

Addendum: Two new laptop models will be available in February: the MacBook Pro, also with the Core Duo Processor, $1999 and $2499.  It will include the iSight camera, Front Row, all that kind of stuff.  Neat!

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Linksys continues to court Linux Hackers

Linksys has sold a bazillion of the old WRT54GS routers. It’s probably due in some small part to the many alternative firmware upgrades you can put on the device to increase its capabilities in a number of innovative directions. The most recent versions of these devices are somewhat less hackable though. The series 5 devices have shifted from using Linux to using VxWorks, and have cut memory down to 2MB of Flash and 8MB of RAM, instead of 4MB of flash and 16MB of RAM for earlier Linux based devices. But to placate the hacker market, Linksys has released the WRT54G”L” which retains the larger memory spaces of earlier models. How long will it last? Hard to say, I’ll be watching this experiment to see how it goes.

Dave Slusher Hacks a $25 Digital Camera

Dave went out and bought himself a couple of those single use, $25 camcorders that CVS is selling these days, and hacked them to allow download of video. What is even better, he snapped video of the project and made it available for download.

Caveat: it appears to be encoded in some kind of Quicktime 7 specific codec. I haven’t bothered to get Quicktime 7 on my laptop, since it is beta still for Windows, but I did notice that it will play nice using VLC. Hooray for VLC!

AMD K8 has reprogrammable microcode

Real World Technologies lists an interesting article about the AMD K8 processor and its previously unnoticed ability to patch its own microcode. Apparently AMD has used this to repair a couple of bugs in the processor in the past, but nobody really noticed it before.

A couple of quotes from the article:

The ability to fundamentally alter instruction decoding and execution on AMD K8 processors is sure to interest hardware hackers everywhere.

For instance, by patching the appropriate microcode lines, it may be possible to catch an opcode that would normally be illegal, and instead handle it by tricking the TLB into thinking we’re in kernel mode when in fact the attacker has only compromised a userspace process. From there, the attacker could control the entire machine, all without altering a single bit of “software”.

That sounds scary. But wait: there is more!

There may also be a hidden danger to altering K8 microcode without complete information. It is possible (though very unlikely) that the microcode could electrically reconfigure signal routing in a fashion similar to FPGAs, for instance to cut off defective logic and reroute signals to redundant arrays. This approach has been used in the past and the AMD patents even suggest it.

If this were the case, there is a very remote chance the CPU itself could be permanently damaged, for instance, by tri-stating pass transistors into a high current draw state or adjusting the K8’s voltage and frequency scaling controls out of spec. This is not meant to discourage potential hackers; I have just seen programmable logic literally destroyed by buggy “software” bitstreams.

Gee, that doesn’t sound very good.