[George Stagg] recently found himself stung by the burden of free time while in lockdown. Needing a project to keep him occupied, he decided to upgrade his 90s Casio CFX-9850G calculator to run custom machine code.
All [George] really wanted was for his vintage calculator to understand Reverse Polish Notation (RPN). The calculator in question can already run its own version of BASIC, however the bespoke Hitachi CPU struggles performance-wise with complex programs, and wouldn’t be a realistic way of using RPN on the calculator. An RPN interpreter written in assembly language would be much faster.
The first step in cracking this calculator wide open was a ROM dump, followed by writing a disassembler. Incredibly, the MAME framework already featured a ‘partial implementation’ of the calculator’s CPU, which was a much needed shot in the arm when it came time to write a full-featured emulator.
With the entire calculator emulated in software, the plan from here involved replacing one of the BASIC commands in ROM with new code that would jump to an address in RAM. With 32KB of RAM there ended up being plenty of room for experimentation, and uploading a program into RAM was simplified by using Casio’s original backup software to dump the RAM onto a PC. Here, the contents of RAM could be easily modified with custom code, then uploaded back into the calculator.
With RAM to burn, new routines were created to write custom characters to the screen, and a new font was created to squeeze more characters onto the display than normal. [George] ended up porting a Forth interpreter, which defaults to RPN style, to finally achieve his humble objective. He also managed to get a version of Conway’s Game Of Life running, check out the video after the break.
We can’t get enough of our calculator hacks here, so make sure to check out the CPU transplant on this vintage Soviet calculator.
Continue reading “Old Casio Calculator Learns New Tricks”
Munged Ferris Bueller quotes aside, Conway’s Game of Life is the classic cellular automata that we all reach for. The usual approach is to just iterate over every cell in the grid, computing the next state into a new grid buffer. [K155LA3] set out to turn that on its head by implementing Game Of Life in the hardware of an FPGA.
[K155LA3]’s version uses Chisel, a new HDL from the Berkley and RISCV communities. Under the hood, Chisel is Scala with some custom libraries that know how to map Scala concepts onto hardware. In broad strokes, Verilog and VHDL are focused on expressing hardware and then added abstraction on top of that over the year. Chisel and other newer HDL languages focus on expressing high-level general-purpose elements that get mapped onto hardware. FPGAs already map complex circuits and hardware onto LUTs and other slices, so what’s another layer of abstraction?
The FPGA chosen for this project is a Digilent Arty A7 with a VGA Pmod to turn the RGB444 into analog signals to actually display. What’s impressive about [K155LA3]’s implementation is just how fast it is. Even running at 60 frames per second it’s almost as fast as the monitor can handle. Of course, most computers lying around you could simulate a 60 x4 8 grid at 60 fps. Next, instead of connecting the grid logic to the 60 Hz VGA clock, he connects it to the 100 MHz board external oscillator. Now each pixel in each frame displayed contains over a million generations.
Unfortunately, even this small grid of 60×48 takes up 90% of the LUTs on the Artix-7. In the future, we’d love to see an even larger FPGA hardware implementation capable of handling grids that could hold whole computers in them. And naturally, this isn’t the first FPGA version of the Game Of Life here at Hackaday.
We often hear the term “Turing-complete” without giving much thought as to what the implications might be. Technically Microsoft PowerPoint, Portal 2, and Magic: the Gathering all are Turing-complete, what of it? Yet, each time someone embarks on an incredible quest of perseverance and creates a computer in one of these mediums, we stand back in awe.
[Nicolas Loizeau] is one such individual who has created a computer in Conway’s Game of Life. Unlike electricity, the Game of Life uses gliders as signals. Because two orthogonal gliders can cancel each other out or form a glider eater if they intersect with a good phase shift, the basic logic gates can be formed from these interactions. This means the space between gates is crucial as signals need to be in phase alignment. The basic building blocks are a period-60 gun, a 90-degree glider reflector, a glider duplicator, and a glider eater.
All the Python code that generates these structures is on GitHub as the sheer size of the machine couldn’t possibly be placed by hand. The Python includes scripts to assemble the basic programs as a bank of selectable glider generators. It’s all based on Golly, which is an excellent program for simulating Conway’s Game of Life, among other things. While this isn’t the first computer in the Game of Life as [Paul Rendell] published a design in 2000 and [Adam Goucher] published a Spartan universal computer constructor in 2009, we think this is a particularly beautiful one.
The actual architecture has an 8-bit data bus, a 64-byte memory with two read ports, a ROM with 21 bits per line, and a one-hot encoded ALU supporting 8 different operations. Instructions have a 4-bit opcode which is decoding in a few different instructions. The clock is four loops, formed by the glider reflectors as the glider beams rotate. This gives the computer four stages: execution, writing, increment PC, and write PC to memory.
The Game of Life is an excellent example of Cellular Automaton (CA). There are several other types of CA’s and the history behind them is fascinating. We’ve covered this field before and delved into this beautiful fringe of computer science. Check out the video below to truly get a sense of the scale of the machine that [Nicolas] has devised.
Continue reading “A Computer In The Game Of Life”
John Conway passed away this week. Even if you don’t know much about mathematics, you will probably know nearly everyone’s favorite cellular automata ruleset: Conway’s “Game of Life”. It’s so much a part of our cultural history, that proto-hacker Eric Scott Raymond suggested using the glider as the hacker emblem.
The idea that a very simple set of rules, applied equally and everywhere, could result in “life” was influential in my growth as a young hacker, and judging from the comments on our article about Conway, I’m not alone. But I won’t lie: I was a kid and thought that it could do much more than make pretty patterns on the screen. I was both right and wrong.
Although amazingly complex machines can be built in Conway’s Life, just check out this video for proof, in the end no grand unifying theory of cellular automata has emerged. As a research topic Conway’s chosen field of mathematics, cellular automata is a backwater. It didn’t really go anywhere. Or did it?
Implementing Conway’s Life in BASIC on a Tandy Color Computer was one of the first things that launched me on my geeky path. It ranks with MENACE: the matchbox-based machine learning algorithm from the 1960’s and an introduction to Markov Chains in the form of a random text generator in my young algorithmic life, all of which I incidentally read about in Martin Gardner’s column in “Scientific American”. Conway’s Life, along with some dumb horse-race game, also taught me about bad random-number generators: the screen would populate the same “randomly” every time on the old CoCo.
So maybe Conway didn’t want to be remembered just for his “Life” because it was a bit of a mathematical dead-end. But in terms of its impact on the world, an entire generation of hackers, and my own personal life, it was able to fill up significantly more than a screen full of pixels. Here’s to Conway, his “Life”, and everyone else who is inspiring the next. You’re not just gliders, you’re glider guns!
[Game of Life example shown in this article is John Conway’s Game of Life – 1.0 written in Python by Nick Jarvis and Nick Wayne]
Programmers everywhere are familiar with Conway’s Game of Life: whether they’ve written a version themselves or simply seen the mesmerizing action resulting from the cellular automata, it’s a household name in all homes where code is spoken. On Saturday April 11th, 2020 its inventor and namesake, John Horton Conway passed away from COVID-19 at the age of 82.
Born in Liverpool, Conway received his PhD in mathematics in 1964 from Gonville and Caius College, Cambridge. He accepted a position at Sidney Sussex College, Cambridge which he held until joining the faculty of Princeton University in 1987. A brilliant mathematician, he received numerous awards and was well known for his work in combinatorial game theory, group theory, and theoretical physics.
Many readers will be familiar with his Doomsday algorithm which can be used to deduce the day of the week for any given date in your head. But by far the rockstar mathematics moment of developing Conway’s Game of Life in 1970 cements him a perpetual place of legend in computing lore. His original work on the concept used pencil and paper as the computing revolution had yet to make digital resources easily available, even to mathematics researchers like Conway.
The game uses an infinite grid of squares where all of the edges of the grid wrap around. Four simple rules (which can be boiled down to three if you’re clever) determine which cells live and which cells die during each frame of the “game”. The only parameters that are needed are the number and position of living cells at the start of the game, and the delay between each game frame. But the effect of this simplicity is not to be understated. The game can be coded by a novice — and it’s become a common challenge in University course work. Small errors, or intentional tweaks, in the implementation have profound effects on behavior of the game. And the effect on the person programming it for the first time can be long lasting. You could call it a mathematics gateway drug, grabbing the curiosity of the unsuspecting mind and pulling it down the rabbit hole of advanced mathematics discovery.
We’d love to celebrate his life by hearing your own stories of programming the Game of Life in the comments below. If you haven’t yet had the pleasure, now’s a great time to take on the challenge.
[Game of Life example shown in this article is John Conway’s Game of Life – 1.0 written in Python by Nick Jarvis and Nick Wayne]
Well all know cellular automata from Conway’s Game of Life which simulates cellular evolution using rules based on the state of all eight adjacent cells. [Gavin] has been having fun playing with elementary cellular automata in his spare time. Unlike Conway’s Game, elementary automata uses just the left and right neighbors of a cell to determine the next cell ahead in the row. Despite this comparative simplicity, some really complex patterns emerge, including a Turing-complete one.
[Gavin] started off doing the calculations by hand for fun. He made some nice worksheets for this. As we can easily imagine, doing the calculations by hand got boring fast. It wasn’t long before his thoughts turned to automating his cellular automata. So, he put together an automatic cellular automator. (We admit, we are having a bit of fun with this.)
This could have been a quick software project but half the fun is seeing the simulations on a purpose-built ecosystem. The files to build the device are hosted on Thingiverse. Like other cellular automata projects, it uses LED matrices to display the data. An Arduino acts as the brain and some really cool retro switches from the world’s most ridiculously organized electronics collection finish the look of the project.
To use, enter the starting condition with the switches at the bottom. The code on the Arduino then computes and displays the pattern on the matrix. Pretty cool and way faster than doing it by hand.
Our Hackaday Chief [Mike] sent me an e-mail the other day with a link to the Belgrade Hackaday Badge simulator. He clearly wanted me to enter something into the demo scene competition. The good news is that because of the simulator, you didn’t have to leave your desk to participate. The bad news is that I had very little time left at the end of the month, so I wanted to do something appealing but it had to be fairly easy to roll out. I wound up doing a very quick project but it had a few fine points that I thought I’d share. The end goal was to have an interesting display of Conway’s game of life on the badge.
By the way, there was a completely different project with the same goal by [Jeremias] on Hackaday.io. As far as I know, this was just the result of two people setting out to do the same thing. You’ll see the user interface is a good bit different, so you might see which you prefer.
If you haven’t seen it, the real badge is below. The emulator, of course, just runs as a window on your PC. For those that will be at the conference, or just want to program closer to the actual hardware, there is now a preconfigured MPLABX framework for the PIC18LF25K50 and the bootloader/kernel running on this badge.
Continue reading “That’s Life…on A Hackaday Badge”