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. None has been built yet, but 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::plotfnint integrates any word between two bounds. The whole bell curve e−x² has an area of exactly √π, and from −6 to 6 the calculator finds it to sixteen digits.
fn bell(x:d128 -- y:d128) { sq neg exp }
"bell" -6.0 6.0 fnint // the area under it
pi sqrt // and the square root of piOr on the graph, as a TI does it: type a curve into Y1, graph it, and CALC finds the integral between two bounds and shades it.
Everything the keys do, a program can do: cfg:: sets the angle mode, and gr:: writes the Y= slots, picks a zoom and presses GRAPH. The taylor app builds sine's Taylor series as text, a term longer each time round a loop, and graphs all six: every term hugs the curve a little further out, and when you leave, your own Y= and settings are put back as they were. Read it in the calculator's own editor, then run it.
Take 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 send the folder over with qdosctl, and the app is there at once.
| 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 | ESP32-S3: two 240 MHz Xtensa LX7 cores, 512 KB of RAM and 8 MB of PSRAM |
| Storage | 16 MB of flash |
| USB | One port. A computer can type at the calculator over it, and send it programs and apps. |
| 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.