Hackaday Links: May 31, 2020

We begin with sad news indeed as we mark the passing of Marcel van Kervinck on Monday. The name might not ring a bell, but his project, the Gigatron TTL computer, certainly will. We did a deep dive on the microprocessor-less computer a while back, and Marcel was a regular at conferences and on the Gigatron forums, supporting users and extending what the computer can do. He was pretty candid about his health issues, and I’ll add that when I approached him a few weeks ago out of the blue about perhaps doing a Hack Chat about Gigatron, he was brutally honest about how little time he had left and that he wouldn’t make it that long. I was blown away by the grace and courage he displayed. His co-conspirator Walter Belger will carry on the Gigatron mission, including joining us for a Hack Chat on June 24. In the meantime, this might be a great time to pick up a Gigatron kit before they’re all sold out and get busy soldering all those delicious through-hole TTL chips.

May of 2020 is the month that never seems to end, and as the world’s focus seems to shift away from the immediate public health aspects of the ongoing COVID-19 pandemic to the long-term economic impact of the response to it, we happened across a very interesting article on just that topic. Mike Robbins from the Circuit Lab has modeled the economic impact of the pandemic using analog circuit simulations. He models people as charges and the flow of people between diseases states as currents; the model has capacitors to store the charge and allow him to measure voltages and filters that model the time delays needed for public policy changes to be adopted. It’s a fascinating mashup of engineering and policy. You can play with the model online, tweak parameters, and see what you come up with.

One of the things that the above model makes clear is that waiting to fully reopen the economy until a vaccine is ready is a long and dangerous game. But there has at least been some progress on that front, as Massachusetts biotech firm Moderna announced success in Phase 1 clinical trials of its novel mRNA vaccine against SARS-CoV-2. It’s important to temper expectations here; Phase 1 trials are only the beginning of human testing, aimed at determining the highest treatment dose that won’t cause serious side effects. Phase 2 and Phase 3 trials are much more involved, so there’s a long way to go before the vaccine, mRNA-1273, is ready for use. If you need to brush up on how these new vaccines work, check out our handy guide to mRNA vaccines.

In happier news, the “moar memory” version of the Raspberry Pi 4 is now on sale. Eben Upton announced that the 8GB version of the Pi 4 is now available for $75. The upgrade was apparently delayed by the lack of an 8GB LPDDR SDRAM chip in a package that would work in the Pi manufacturing process. They’ve also released a beta of a 64-bit version of the Raspberry Pi OS, if you’re interested in a bleeding-edge flex.

And finally, for those who missed the first wave of the computer revolution and never had a blinkenlight machine, you can at least partially scratch that itch with this Internet-connected Altair 8800. Jesse Downing has written a queueing system that allows users to connect to the machine via ssh and use Microsoft BASIC 5.0 on CP/M. Need to see those glorious front panels lights do their thing? Jesse has kindly set up a live stream for that, with an overlay of the current console output. It’s a great way to relive your misspent youth, or to get a taste of what computing was like when soldering skills were a barrier to entry.

Emulating An Altair 8800 On An Apple II

The Altair 8800 was, to its creators, a surprise hit. Despite looking nothing like what we would today consider to be a computer, it sold thousands of units almost immediately upon its launch, way back in 1975. A few years later, the Apple II burst onto the scene, and the home computer revolution began in earnest.

Emulating older machines on newer hardware has always been a thing, and [option8] has coded an Altair 8800 emulator for the Apple II. Of course, if you don’t have one lying around, you can run this emulator on an Apple II emulator right in your browser. Honestly, it’s emulators all the way down.

As far as emulators go, this is a particularly charming one, with the Altair’s front panel displayed in glorious color on the Apple’s 40 column screen. Replete with a full set of switches and blinking LEDs, it’s a tidy low-resolution replica of the real thing. Instructions to drive it are available, along with those for another similar emulator known as Apple80.

If that still hasn’t quenched your thirst, check out this Game Boy emulator that lives inside emacs.

VCF East: SDR On The Altair 8800

You’d be forgiven if you thought software defined radio (SDR) was a relatively recent discovery. After all, few outside of the hardcore amateur radio circles were even familiar with the concept until it was discovered that cheap USB TV tuners could be used as fairly decent receivers from a few hundred MHz all the way up into the GHz range. The advent of the RTL-SDR project in 2012 brought the cost of entry level SDR hardware from hundreds of dollars to tens of dollars effectively overnight. Today there’s more hackers cruising the airwaves via software trickery than there’s ever been before.

Continue reading “VCF East: SDR On The Altair 8800”

Doing It With Fewer Bytes Than Bill Gates

The MITS Altair 8800 occupies a unique place in computing history as the first commercially succesful microcomputer for personal rather than business use. It is famous as the platform upon which the first Microsoft product ran, their first BASIC interpreter.

[Josh Bensadon] has an Altair 8800, and became intrigued by its bootloader. The simplest method of programming the machine is through binary using a set of switches on the front panel, and he remarks that there should be a warning in the manual: “fingers will get sore after repeated use of the small switches on the ALTAIR”.

In the Altair manual there are two listings, one 21 byte, and another in 20 bytes. Bill Gates is on record as saying that their first effort was 46 bytes long, but with more work he managed to create one in 17 bytes. Now [Josh] has beaten that, he’s created an Altair 8800 bootloader in only 14 bytes.

His write-up goes into great detail about how those bytes are shaved off, and provides us with a fascinating insight into the 8800’s architecture. Even if your 8-bit assembler is a little rusty, it’s a fascinating read.

We’ve featured Altair-inspired projects many times here at Hackaday, but rarely the real thing. This Altair PC case with the ability to emulate the original was rather a nice idea, as was this Altair front panel project. If you want the joy without the heartache though, there is an online emulator.

Arduino Altair 8800 Simulator

Browse around eBay for an original Altair 8800 and you quickly find that the price range is in the thousands of dollars. If you are a collector and have some money in your pocket maybe that’s okay. But if you want the Altair 8800 experience on a budget, you can build yourself a clone with an Arduino. [David] kindly shared the build details on his Arduino Project Hub post. Using an Arduino Due (or a Mega for 25% of original speed), the clone can accurately reproduce the behavior of the Altair’s front panel elements. We covered a similar project in the past, using the Arduino Uno.

While not overly complicated to build one, you will need a backfair amount of patience so you can solder all the 36 LEDs, switches, transistors, and resistors but in the end, you’ll end up with a brand new computer to play with.  In 1975, an assembled Altair 8800 Computer was selling for $621 and $439 for an unassembled version. Sourced right, your clone would be under 50 bucks. Not bad.

The simulator comes with a bunch of software for you to try out and even games like Kill-the-Bit and Pong. BASIC and Assembler example programs are included in the emulator software and can easily be loaded.

In addition, the simulator includes some extra functions and built-in software for the Altair which are accessible via the AUX1/AUX2 switches on the front panel (those were included but not used on the original Altair). From starting different games to mount disks in an emulated disk drive, there are just too many functions to describe here. You can take a look at the simulator documentation for more information.

In case you don’t know already, here’s how to play Kill-the-Bit:

Continue reading “Arduino Altair 8800 Simulator”

Altair 8800 Front Panel For An 8080 Emulator

It appears a very important anniversary passed by recently without anyone realizing. The January 1975 issue of Popular Electronics featured the Altair 8800 on the cover, otherwise known as the blinky box that launched a revolution, the machine that made Microsoft a software powerhouse, and the progenitor of the S-100 bus. The 40-year anniversary of the Altair wasn’t forgotten by [dankar], who built a front panel emulator with the help of some much more modern components.

The build unofficially began with an Intel 8080 emulator written for an Arduino. The 8080 is the brains of the Altair, and while emulators are cool, they don’t have the nerd cred of a panel of switches and LEDs. The hardware began as a bunch of perfboard, but [dankar] wired himself into a corner and decided to make a real schematic and PCB in KiCAD.

Despite the banks of LEDs and switches, there really isn’t much to this front panel. Everything is controlled by shift registers, but there is a small amount of SRAM in the form of an SPI-capable 23LC1024. This comes in handy, because [dankar] is running CP/M 2.2 on this front panel emulator from disk images saved on an SD card. Everything you would want from a computer from 1975 is there; an OS, BASIC, and enough I/O to attach some peripherals.

Online Altair 8800 Clone Lets You Play Zork

[Citponys] wanted to share their Altair 8800 clone with the world, and what better way to do so than by hooking it up to the Internet? This hack was pulled off by using a Linux computer which receives a Telnet connection and redirects it to a serial port. This serial port is connected to the Altair clone. In order to connect the serial port to the Internet using TCP, the ser2sock program was used. People can interact with the Altair on the webpage, where there is also a live camera feed showing the Altair’s Blinkenlights.

This is an ongoing project for [Citponys]. Zork 1-3 and Ladder are now available for play. You can interact with other people in the current session; play nice, or it’ll end up a Mad Libs version of ‘Twitch Plays Pokemon’.  Most recently, [Citponys] updated the webpage with a HTML5-embedded terminal emulator. If you want to quit the current session displayed, enter “quit” and you will be redirected to the main menu where you can choose another game. [Citponys] has links to game walkthroughs on the top of the page. We have a soft spot for classic computers and games, especially the Altair. Take a trip down memory lane and play some Zork at the fork where the past meets the present!

[via Reddit]