MB-RPN is a .NET Blazor WebAssembly financial calculator with its own dark, glowing visual identity and an interactive history panel. It is an independent implementation that is functionally compatible with the HP-12C: RPN stack discipline, 10-significant-digit arithmetic, the financial solvers, dates, statistics, and full keystroke programming on the same keyboard layout, matching the documented behavior of that calculator.
dotnet run --project src\MBRPN.Web # dev server
dotnet test # engine test suite (handbook examples)
dotnet publish src\MBRPN.Web -c Release # static site in bin\Release\net10.0\publish\wwwroot
Requires the .NET 10 SDK.
One-time setup:
gh auth login(GitHub CLI, interactive).gh repo create mbrpn --public --source . --push— creates the repo and pushesmain.- After the first deploy (step below), enable Pages once:
gh api repos/{owner}/mbrpn/pages -X POST -f "source[branch]=gh-pages" -f "source[path]=/"(or Settings → Pages → Deploy from a branch →gh-pages).
Every deploy after that: run deploy.cmd (double-click, or .\deploy.ps1). It runs
the test suite, publishes a Release build, patches the output for Pages (base href
/mbrpn/, .nojekyll, 404.html), and force-pushes it to the gh-pages branch. The
site is served at https://<your-username>.github.io/mbrpn/ about a minute later.
The repo must stay public for free Pages hosting; the deployed app's saved state lives
under the github.io origin, separate from localhost.
| Project | What it is |
|---|---|
src\MBRPN.Engine |
UI-independent calculator engine. CalculatorEngine.Press(KeyId) in, DisplayState out; interaction history with structured replay. |
src\MBRPN.Web |
Blazor WASM front end: dark-tech CSS faceplate, glowing SVG seven-segment display, history panel, keyboard mapping, localStorage continuous memory. |
tests\MBRPN.Engine.Tests |
xUnit suite (144 tests) driving the engine key-by-key and asserting on display text, using the handbook's worked examples, plus history recording/replay and rename-verification tests. |
- RPN stack — X/Y/Z/T, LAST X, exact stack-lift rules (ENTER/CLx/Σ+ disable lift, T replicates on drop), 10-digit mantissa entry, EEX, CHS.
- Display — FIX 0–9 with thousands separators, scientific mode (f .), overflow
9.999999 99, mantissa peek (f CLEAR PREFIX), RND. - Math — + − × ÷, yˣ, 1/x, √x, LN, eˣ, n!, FRAC, INTG, %, Δ%, %T with HP domain errors.
- Storage — R0–R9, R.0–R.9, STO arithmetic (
STO + 4), Error 1 on overflow. - TVM — n, i, PV, PMT, FV with the store-vs-compute rule, BEGIN/END modes, odd periods
(simple or compound via
STO EEX, C annunciator), n rounded up as on the real unit, iterative i solver, 12× / 12÷, CLEAR FIN. - AMORT — per-payment interest rounded to the current FIX setting (results depend on the display setting, exactly like the hardware); INT (360- and 365-day simple interest).
- NPV / IRR — CF₀/CFⱼ/Nⱼ stored in the real machine's registers, grouped discounting, bracketing solver, Errors 3/7.
- Bonds — f PRICE / f YTM, semiannual actual/actual with the final-period simple-interest case.
- Depreciation — SL, SOYD, DB with salvage floor.
- Dates — D.MY / M.DY, g DATE with weekday digit, g ΔDYS (actual + 30/360), Error 8.
- Statistics — Σ+/Σ− into R1–R6, x̄/ȳ, x̄w, s, linear estimates x̂,r / ŷ,r.
- Programming — P/R, 8 lines growing to 99 by converting registers (7 lines each),
keycode display (
43,33 00), R/S, SST/BST, GTO nn, GTO . nn editing, PSE, x≤y, x=0, g MEM (P-08 r-20), non-blocking run loop in the UI. - Continuous memory — full state persists to localStorage; ON toggles the display off without losing anything.
- Interactive history — the panel beside the calculator records meaningful
operations (coalesced number entry + operation, e.g.
100 ENTER,25 +with its result). Every entry is stored structurally as its logical key sequence; clicking one replays exactly that operation against the calculator's current state (no snapshot restore) and records itself as a new entry. Clear button empties it; history is session-only. On narrow screens it moves below the calculator; in mobile-landscape full-screen mode it is hidden.
digits 0–9 . Enter + − × ÷ % — as printed. f g prefixes; s STO, r RCL,
n i, p PV, m PMT, v FV, c CHS, e EEX, y yˣ, x x≷y, d R↓, q 1/x,
l %T, Space R/S, ↓ SST, Backspace/Delete CLx, Esc ON.
- Numbers are stored as a 10-significant-digit decimal mantissa plus exponent (±99),
mirroring the HP-12C's BCD registers, so
1 ÷ 3 × 3 = 1.00and FIX rounding behave like the hardware. Transcendentals compute in double precision and round back to 10 digits. - Iterative solvers (i, IRR, YTM) bracket and bisect exactly the classes of roots the handbook documents, and report the handbook's error numbers when no single answer exists.
- The 7-segment display, teal/violet shifted legends, CLEAR rule, and tall ENTER key are drawn entirely with CSS/SVG — no images. The layout matches the HP-12C keyboard; the visual identity (graphite case, glowing segments) is MB-RPN's own.
- On touch devices the keyboard-shortcut hints are hidden and the calculator scales to
the viewport; in landscape it fills the screen edge-to-edge like a real calculator
(
mbrpn.fit()inwwwroot/js/interop.js; append?mobile=1to preview on desktop).
MIT — see LICENSE.
MB-RPN is an independent implementation and is not affiliated with, authorized by, or endorsed by HP Inc. HP and HP-12C are trademarks of HP Inc., used here only to describe compatibility.