r8 One is an open-source pocket calculator with a keypad laid out for RPN, a memory LCD that needs no backlight, and a shell that runs the programs you type on it. The one on this page is running its real firmware.
Press a sequence like this one to type it in, or click the calculator and use your keyboard. Esc clears the line and F1 to F5 are the keys under the screen.
Tap a sequence like this one to type it in, or tap the keys yourself.
Your stack and programs are kept in this browser, so they are still here when you come back.
The display is a 2.7-inch Sharp memory LCD, 400 by 240 pixels, each one either ink or paper. It reflects the light around it instead of making its own, and it holds its picture with no power at all, so a calculator left on its stack costs next to nothing to keep showing it.
One bit per pixel is the whole colour budget. Everything the calculator draws is designed for it, from the stack to the graphs.
The calculator is RPN: digits build a number, Enter pushes it, and an operator works at once. Undo takes back the last key, and Esc never touches the stack.
A line takes whole Quadrate, with definitions, loops and strings. Define a word in one and it works on the stack like any key.
On the r8 One you type these on the keypad. Here, Run types them in for you, fast enough to watch, and leaves you on the result. Esc on the calculator comes back out.
A word with a stack signature, a counted loop, and two locals named with -> each time round.
fn fib(n:i64 -- r:i64) {
0 1 rot // the first two, under n
0 swap 1 for i {
-> b -> a // name the pair
b a b + // and step it along
}
drop
}
30 fibForty-two lines between the edges of the screen, and a parabola appears in each corner where they cross.
fn art( -- ) {
ui::cls
0 21 1 for i {
0 i 12 * i 20 * 239 ui::line
399 239 i 12 * - 399 i 20 * - 0 ui::line
}
ui::show
loop {
30 ui::frame drop
ui::pressed "" != if { return } // any key leaves
}
}
artTwo words: one turns the ball back at a wall, the other draws it frame after frame, asking ui::frame for sixty a second.
// The speed, turned back at either wall
fn wall(p:d128 v:d128 hi:d128 -- r:d128) {
rot dup 10.0 < if { drop drop abs return }
< if { abs neg return }
}
fn bounce( -- ) {
200.0 -> x 120.0 -> y
3.0 -> dx 2.0 -> dy
loop {
60 ui::frame drop
ui::pressed "" != if { return }
x dx + -> x y dy + -> y
x dx 390.0 wall -> dx
y dy 230.0 wall -> dy
ui::cls
x y 10.0 1 ui::circle
ui::show
}
}
bounceA word that takes x and leaves y is a function to plot. On the graph, TRACE follows the curve and CALC finds its zeros, extremes and areas.
fn f(x:d128 -- y:d128) { dup sin * }
-12.0 12.0 -12.0 12.0 ui::window
"f" ui::plotTake x and y, leave z, and graph3 draws the surface as a wireframe. The arrows turn and tilt it, and + and − zoom.
fn g(x:d128 y:d128 -- z:d128) {
dup * swap dup * + sqrt sin 4.0 * // a ripple
}
"g" graph3A word made at the prompt lasts until the calculator is switched off. To keep one, open APPS, press NEW and write it in the editor.
a+bi or in polar form.These come with it, each a Quadrate program you can open and read.
An app is a folder with a main.qd in it. Plug the calculator into a computer and it shows up as a drive: drop the folder on it, and the app is there when you unplug.
| Display | Sharp LS027B7DH01 memory LCD, 2.7 inches, 400 × 240, reflective |
|---|---|
| Keypad | 54 keys in 10 rows, with an Alpha face for letters and a Symbol face for Quadrate |
| Computer | Raspberry Pi Zero W: 1 GHz ARM11, 512 MB. The firmware also runs on an ESP32-S3. |
| Storage | microSD card |
| USB | One port. A keyboard plugs into it, and a computer sees the calculator as a drive. |
| Size | 98.5 × 214.1 × 32 mm |
| Software | QDOS, free software under the GNU GPL |
In development. The parts are chosen and the software runs: what you are typing on is QDOS itself, compiled for the browser. No r8 One has been built yet, so there is nothing to order.
Everything is open, from the firmware to the case. Follow along, or build one with us.