[Alessandro Carminati] spends the day hacking Linux kernels, and to such an end needed a decent compilation machine to chew through the builds. One day, this machine refused to boot leaving some head-scratching to do, and remembering the motherboard diagnostics procedures of old, realized that wasn’t going to work for this modern board. You see, older ISA-based systems were much simpler, with diagnostic POST codes accessible by sniffing the bus with an appropriate card inserted, but the modern motherboard doesn’t even export the same bus anymore.
Do modern machines even run a POST test at all, or are there other standards? After firing up a Linux machine and dumping the first meg of memory address space, it clearly contained some of the BIOS code. [Alessandro] looked at a disassembly of the BIOS update image and saw a similar structure, with POST code data sent to port 0x80 just like machines of old.
But instead of an ISA CPU bus, we have the Low Pin Count (LPC) bus which is used to hook up the ‘super IO’ functions, controlling things such as fans, temp sensors, and other system management functions. It also serves as the connection for the TPM feature, which usually appears as one of the motherboard connectors intended to be user-accessible. It turns out that POST codes can be accessed from this point with an appropriate POST card that can talk LPC.
We’re not sure if there’s any single characteristic that qualifies someone as a hacker. After all, we’re a pretty eclectic bunch, with skills that range all over the map, and what one person feels is trivial, others would look upon as black magic. But there’s one thing we’re sure of: if you find yourself reading the original POST code for the PC-XT motherboard just to get a keyboard working, you’re pretty much our kind of people.
That was the position [Anders Nielsen] found himself in as work progresses on his “PC-XT from Scratch” project, which seeks to build a working mid-80s vintage IBM Model 5160 using as many period-correct parts as possible. The first installment of the series featured the delicate process of bringing the motherboard up, lest the magic smoke was released. After seeing some life out of the old board, [Anders] needed a little IO, specifically video and keyboard. The video side of the equation was relatively trivial, with an early-90s VGA card from eBay — not exactly period correct, but good enough to get something to display. Continue reading “Connecting A Keyboard To A Vintage PC-XT, The Hard Way”→
Life is full of tough decisions, such as deciding whether you want to go to the end of the drive to check if the mail has arrived. These questions are made even more arduous in the winter months, but [Catpin] has a solution. The Mail Box Alert uses an Electric Imp, a solar panel and a proximity sensor to let you know if you’ve got mail.
It’s a neat build, with the brains provided by that Electric Imp which handles most of the heavy lifting. This wakes up every five minutes and checks whether the status of a small proximity sensor has changed. If it has, it pings a website. The unit sits at the bottom of the postbox, so if your friendly neighborhood post person has put in any letters, it will have changed. The Imp is powered by a small battery, which is in turn charged by a solar panel. That means that it doesn’t require any power cables or other wiring, as long as it is in the range of WiFi. With the addition of a 15-hours overnight deep sleep, [Catpin] found that the whole thing could be run from a couple of 18650 LiPo batteries.
Perhaps the most interesting part of the writeup was discussing the problems that he found with the build, such as the fact that a LiPo battery won’t perform that well in a Wisconsin winter. So, this was replaced with a Lithium Iron Phosphate battery that should be a bit more tolerant of the chill. There is also a writeup on how to create the same project using an ESP8266 if required.
Back in the 70s when I started getting interested in electronics, tons of magazines catered to the hobbyist market. Popular Electronics was my favorite, and I think I remember the advertisements more than anything, probably because they outnumbered articles by a large margin. Looking back, it seemed like a lot of ad space was sold to companies hawking the tools and materials needed for wire wrapping, which was very popular for prototyping in the days before solderless breadboards were readily available. I remember beauty shots of neat rows of small, gold posts, with stripped wires wrapped evenly around them.
To the budding hobbyist, wire wrapping looked like the skill to have. With a huge selection of posts, terminals, and sockets for ICs and discrete components, as well as a wide range of manual and powered wrapping tools, it seemed like you could build anything with wire wrapping. But fast forward just a decade or so, and wire wrapping seemed to drop out of favor. And today — well, does anyone even wire wrap anymore?