There’s pandemonium on the streets. You look down from your 4 story apartment and see hundreds of people marching and chanting. You pick up your phone and call your buddy, expecting it to link up to the nearest cell tower which will route your call to where it needs to go. Instead, without your knowledge, you link to a tricked-out police surveillance truck a few blocks away. They intercept your call and listen to the conversation in hopes of tracking the protest.
The Macintosh Classic – a small all-in-one computer with a 9″ monochrome screen – was one of the more interesting machines ever released by Apple. It was the company’s first venture into a cost-reduced computer, and the first Macintosh to sell for less than $1000. Released in 1990, its list of features were nearly identical to the Macintosh Plus, released four years earlier. The Classic also had an interesting feature not found in any other Mac. It could boot a full OS, in this case System 6.0.3, by holding down a series of keys during boot. This made it an exceptional diskless workstation. It was cheap, and all you really needed was a word processor or spreadsheet program on a 1.44 MB floppy to do real work.
[Steve] over at Big Mess O’ Wires had the same idea as the Apple engineers back in the late 80s. Take a Macintosh Plus, give it a bit more ROM, and put an OS in there. [Steve] is going a bit farther than those Apple engineers could have dreamed. He’s built a rewritable ROM disk for the Mac Plus, turning this ancient computer into a completely configurable diskless workstation.
The build replaces the two stock ROM chips with an adapter board filled with 29F040B Flash chips. They’re exactly what you would expect – huge, old PDIPs loaded up with Flash instead of the slightly more difficult to reprogram EEPROM. Because of the additional space, two additional wires needed to connected to the CPU. The result is a full Megabyte of Flash available to the Macintosh at boot, in a computer where the normal removable disk drive capacity was only 800kB.
The hardware adapter for stuffing these flash chips inside a Mac Plus was made by [Rob Braun], while the software part of this build came from [Rob] and [Doug Brown]. They studied how the Macintosh Classic’s ROM disk driver worked, and [Rob Braun] developed a stand-alone ROM disk driver with a new pirate-themed startup icon. [Steve] then dug in and created an old-school Mac app in Metrowerks Codewarrior to write new values to the ROM. Anything from Shufflepuck to Glider, to a copy of System 7.1 can be placed on this ROM disk.
This isn’t the first time we’ve seen ROM boot disks for old Macs. There was a lot of spare address space floating around in the old Mac II-series computers, and [Doug Brown] found a good use for it. Some of these old computers had optional ROM SIMM. You can put up to 8 Megabytes in the address space reserved for the ROM, and using a similar ROM disk driver, [Doug] can put an entire system in ROM, or make the startup chime exceptionally long.
Some people really like eating specific M&M colors… You could spend hours sorting your packs of M&M’s into color specific piles, or you could build a machine to do it for you.
That’s exactly what [ReviewMyLife] decided to do, and it’s quite impressive! He’s using a rotating hopper to release M&M’s into a chute one-by-one, and then an iPhone to perform color recognition as the M&M falls past it. That information is then communicated over Bluetooth to the Arduino which actuates a high-speed electromagnetic gate to force the M&M down the right chute for sorting.
The machine works surprisingly well for a prototype that was hot glued together out of foam board, but fear not, he plans to upgrade it now that the proof of concept has been confirmed. He’s hoping to get rid of the iPhone and replace it with a Raspberry Pi for starters, 3D print some of the parts, and consolidate its power supply. Currently he’s using three separate supplies to power the Arduino, electromagnets, and the hopper motor — not very efficient!
Continue reading “Hate Blue M&M’s? Sort Them Using The Power Of An IPhone!”
This is a wonderful example of the phenomenon of “feature creep”. [Gert] was working on getting a VGA output running on an mbed platform without using (hardly) any discrete components. Using only a few resistors, the mbed was connected to a VGA display running at 640×480. But what could he do with something with VGA out? He decided to emulate an entire Sinclair ZX81 computer, of course.
With more than 1.5 million units sold, the Sinclair ZX81 was a fairly popular computer in the early ’80s. It was [Gert]’s first computer, so it was a natural choice for him to try to emulate. Another reason for the choice was that his mbed-VGA device could only output monochrome color, which was another characteristic of the ZX81.
[Gert] started by modifying a very lean Z80 emulator to make the compiled code run as efficiently as possible on the mbed. Then he went about getting a picture to display on the screen, then he interfaced an SD card and a keyboard to his new machine. To be true to the original, he built everything into an original ZX81 case.
This isn’t the first time we’ve seen a ZX81, but it is one of the better implementations of an emulated version of this system we’ve seen.
Thanks to [Jeroen] for the tip!
Have you ever taken a First Aid & CPR training course? Don’t you just love the realism of the dummy mannequins you get to practice on? [Park, Qurashi, & Chen], who are students of Cornell University, thought the dummies could use an intelligent upgrade.
It’s the final project for their electrical and computer engineering course ECE 4760. And what they’ve done is successfully created a budget friendly CPR not-so-dumb dummy using the venerable ATmega1284 microcontroller.
The dummy can sense when chest compressions are given, if the nose is plugged properly when breaths are given, if the head is tilted back properly to open the airway, and it even makes use of a microphone to detect if breaths are given properly! While it does this, it uses LED eyes and an LCD screen to provide training feedback to the student. Once the students are sufficiently practiced, it also has a “real” mode that doesn’t give you any feedback to make sure the students truly learned the technique. Continue reading “Smart CPR Dummy Makes Sure You Do It Right”
Developing film at home is most certainly a nearly forgotten art nowadays, but there are still a few very dedicated people who care enough to put in the time and study to this craft. [Jan] is one of the exceptional ones. He’s developing 35mm film with Lego (Dutch, Google translate).
For the build, [Jan] is using the Lego RCX 1.0, the first gen of the Lego Mindstorms, released in the late 90s. According to eBay, this is a significantly cheaper option for programmable Lego. The mechanics of the Lego film developer consisted of multiple tanks of chemicals. The film was loaded on a reel, suspended from a Lego gantry, and dunked into each tank for a specific amount of time.
A second revision of the hardware (translate) was designed, with the film loaded into a rotating cylinder. A series of chemicals would then be pumped into this unit with the hope of reducing the amount of chemicals required. This system was eventually built using the wiper fluid pump from a car. Apparently, the system worked well, judging from the pictures developed with this system. Whether it was easy or efficient is another matter entirely.
You can check out a video of the first revision of the Lego film developing system below.
Thanks [Andrew] for sending this in.
Tesla coils are always a hit around here at the office. Giant ones that play music with modern-day chain mail wearing DJ’s, ones thrown together in garages by self-proclaimed mad scientists… But have you ever seen one that can fit in the palm of your hand?
[Ludic Science] just released this tutorial video on how to make it. It’s a miniature 
solid state Tesla coil that’s based on the ever popular Slayer Exciter circuit that was first developed by [GBluer]. The beauty is it’s a very simple circuit to build. It consists of one power transistor, a few diodes, some resistors, and the coil. That’s it!
He even repurposes the magnet wire from a small relay, it’s literally a project you can build from scrap parts around the shop. Awesome.
Continue reading “Micro Tesla Coil Makes A Perfect Stocking Stuffer”
