Contents

Section	Topic
1	About this Volume
2	Use-Case Playbooks: Calculator and Games
· 2.1	PicoCalc as a fully-functional graphing calculator
· · 2.1.1	Path A — PicoMite + custom BASIC programs
· · 2.1.2	Path B — uLisp with symbolic algebra
· · 2.1.3	Path C — MicroPython + sympy port
· · 2.1.4	Comparison vs. dedicated graphing calculators
· 2.2	PicoCalc as a retro-game console
· · 2.2.1	What’s playable
· · 2.2.2	Setup steps for NES emulation
· · 2.2.3	Sourcing ROMs ethically
· · 2.2.4	Keyboard-to-controller mapping
· · 2.2.5	Audio — making games sound tolerable

1. About this Volume

This volume covers two end-to-end use cases: the PicoCalc as a fully-functional graphing calculator, and the PicoCalc as a retro-game console.

For the calculator role, three implementation paths are walked through: PicoMite + custom BASIC programs (works on any Pico), uLisp with symbolic algebra (RP2040-only, niche), and MicroPython + a stripped-down sympy port (Pico 2 only, RAM-bound but the fullest symbolic capability). The chapter ends with a head-to-head comparison against the dedicated graphing-calculator market — TI-84 Plus CE and NumWorks N0110.

For the game-console role, the chapter covers what’s actually playable on each Pico variant (NES, GB, GBC, SMS, GG, TIC-80), where to source ROMs ethically, how to map the PicoCalc keyboard to standard game-controller inputs, and what audio mods (Volume 6, Volume 7) make the experience tolerable.

2. Use-Case Playbooks: Calculator and Games

2.1 PicoCalc as a fully-functional graphing calculator

The PicoCalc has the right shape for a graphing calculator: a screen big enough to show plots, a real keyboard, and a battery. Three implementation paths:

2.1.1 Path A — PicoMite + custom BASIC programs

PicoMite’s MMBasic dialect has built-in PLOT, LINE, CIRCLE, RECTANGLE, TEXT, plus full IEEE-754 double-precision math. Floor-effort graphing calculator in BASIC:

' Plot y = sin(x) for x in [-2*PI, 2*PI]
CLS
DRAW LINE 0, 160, 320, 160, RGB(GRAY) ' x-axis
DRAW LINE 160, 0, 160, 320, RGB(GRAY) ' y-axis
FOR x = -2*PI TO 2*PI STEP PI/160
  px = 160 + x * (160/(2*PI))
  py = 160 - SIN(x) * 100
  PIXEL px, py, RGB(BLUE)
NEXT x

This works on any Pico variant (the only bottleneck is interpreter speed — a few hundred ms per plot on Pico 1, near-instant on Pico 2).

For full graphing-calc functionality, you need:

• Function entry parser: parse y = sin(x) + cos(2x) into evaluable form. PicoMite’s EVAL does this for free.
• Multi-function plotting: use multiple colors.
• Zoom/pan via keyboard: read arrow keys, redraw with new bounds.
• Trace mode: cursor along the plotted curve, show coordinates.
• Numerical integration / differentiation: implement Simpson’s rule and central differences in BASIC.
• Symbolic differentiation / simplification: harder — PicoMite has no symbolic library. See path B or C.

Reference implementation: https://forum.clockworkpi.com/t/rpn-calculator-for-picocalc-v1/19917 (“RPN Calculator for PicoCalc V1”) is an HP48-inspired BASIC implementation that covers most of the above. ~800 lines of BASIC.

2.1.2 Path B — uLisp with symbolic algebra

uLisp can evaluate symbolic expressions natively (it’s a Lisp). A small symbolic-math library in Lisp covers differentiation, simplification, and limit-style transformations. Caveats: uLisp is RP2040-only as of v1.1, and symbolic stacks consume RAM fast — long expressions can OOM.

2.1.3 Path C — MicroPython + sympy port

sympy is a full-featured symbolic-math library for Python. There is no full sympy for MicroPython (too big — sympy is ~30 MB), but a stripped-down subset called mpsympy exists for educational use. Capabilities:

• Symbolic differentiation, integration, simplification.
• Equation solving (linear and basic quadratic).
• Plotting via the LofiFren display module.

Memory is the binding constraint: even the stripped subset wants 200+ KB of RAM. Only viable on Pico 2 because of its 520 KB SRAM.

2.1.4 Comparison vs. dedicated graphing calculators

Feature	PicoCalc (PicoMite)	PicoCalc (Path C)	TI-84 Plus CE	NumWorks N0110
Plot speed	Fast on Pico 2	Medium	Medium	Fast
Display resolution	320×320	320×320	320×240	320×240
Numerical accuracy	Double precision	Arbitrary precision	14 digits	Double
Symbolic math	No (path A)	Yes (limited)	No (CE)	Yes (KhiCAS)
Open source / programmable	Yes	Yes	Limited	Yes
Battery life	~30 h	~25 h	100+ h (AAA)	~30 h
Cost	$75 + module	$75 + Pico 2	$130	$100

Verdict: a PicoCalc on Path A or Path C is competitive with the TI-84 Plus CE for plotting and beats it for programmability. For symbolic math the NumWorks N0110 is the strongest dedicated alternative; PicoCalc on Path C is competitive but RAM-limited for large expressions.

2.2 PicoCalc as a retro-game console

2.2.1 What’s playable

System	Best Pico	Frame rate	Notes
NES	Pico 1	60 fps	pico-infonesPlus, ships in factory bundle
Game Boy (DMG)	Pico 1	60 fps (just)	Pico-GB (YouMakeTech)
Game Boy Color	Pico 2	60 fps	peanutGB, gb-rp2350
Sega Master System	Pico 2	60 fps	pico-sms
Game Gear	Pico 2	60 fps	pico-sms with 8x scaling
Game Boy Advance	none	unplayable	Use Pi Zero 2 W (Doc 3)
SNES	none	unplayable	Use Pi Zero 2 W (Doc 3)
TIC-80 fantasy	Pico 2	60 fps	pico2-tic80
PicoMite games	both	60 fps	Geoff Graham’s site has 50+ games

Figure 2.2.2 — NES emulation reference. File:PuNES NTSC main2.png by Gameposo. License: CC BY-SA 4.0. Via Wikimedia Commons.

2.2.2 Setup steps for NES emulation

1. Download pico-infonesPlus UF2 from https://github.com/fhoedemakers/pico-infonesPlus/releases (pick the picocalc build for the right architecture).
2. Copy to pico1-apps/nes_emu.uf2 (or pico2-apps/nes_emu.uf2).
3. Create pico*-apps/roms/nes/ on the SD and put .nes ROMs there. The emulator scans this folder.
4. Boot with the bootloader hotkey held; select the NES emulator.
5. The emulator’s own menu lets you pick which ROM to load.

2.2.3 Sourcing ROMs ethically

• Public-domain / homebrew ROMs: https://www.nesworld.com/ has hundreds. https://itch.io/games/free/tag-game-boy for GB homebrew.
• Dump from your own carts: a CartReader (search “open-source NES dumper” on GitHub) reads your physical cartridges into .nes files. This is the legally safest route for retail games — you own the cartridge.
• Don’t: download “ROM packs” from random sites. Most of these are commercial games whose copyright is still active; the legal status varies by jurisdiction but is broadly not in your favor.

Figure 2.2.3 — Game Boy Color emulation reference. File:Gambatte Emulator.jpg by Wikimedia Commons contributor. License: CC BY-SA 4.0. Via Wikimedia Commons.

2.2.4 Keyboard-to-controller mapping

The PicoCalc has no gamepad — its 67-key keyboard stands in. Every emulator needs a key map from the PicoCalc’s physical keys to the console’s virtual buttons. The conventions that work well:

Console button	PicoCalc key	Notes
D-pad	Arrow keys	Native — the PicoCalc’s four-way D-pad cluster maps 1:1
A	Z	Left-hand home row, comfortable for long sessions
B	X	Adjacent to A; mirrors the NES controller layout
Start	Enter	Intuitive
Select	Right Shift	Out of the way, hard to hit accidentally
L / R (GBC)	A / S	Only needed for GBC; mirrors WASD-adjacent placement
Turbo A / B	C / V	Optional; some emulators support auto-fire

Most PicoCalc emulators (pico-infonesPlus, peanutGB, pico-sms) read keys via the STM32 keyboard coprocessor’s I²C interface (same path as normal typing). The key map is typically a #define block near the top of the emulator’s source — edit, rebuild, reflash.

If you want to remap at the keyboard-coprocessor level instead (so the map persists across all firmware), see Volume 6 §6.1 for the STM32 keymap modification procedure.

2.2.5 Audio — making games sound tolerable

The PicoCalc’s stock speakers are small and tinny. For gaming this ranges from “fine for chiptune NES” to “painful for anything with sampled audio.” Three tiers of improvement:

1. Software volume control. Most emulators expose a volume setting. Start here — turning down to ~60% eliminates the worst clipping distortion from the tiny speakers.
2. Headphone jack. The PicoCalc has a 3.5 mm headphone jack wired to the same audio path. Plug in any decent earbuds and the experience transforms. This is the zero-effort fix.
3. Hardware audio mods. Volume 6 §6.2 covers the speaker-grille mod (~6 dB improvement for two minutes of Dremel work). Volume 7 §10.1 covers the PCM5102A I²S DAC add-on — true 24-bit audio with its own headphone amp, which turns the PicoCalc into a genuinely good-sounding device. Overkill for NES chiptunes, but worth it if you’re also using the PicoCalc for music playback or ham-radio audio (Volume 11).