The R47: A new physical RPN calculator

Original Article ↗ Hacker News Discussion ↗

Project & Hardware

  • R47 is presented as a “what HP might build today” RPN calculator, co-developed with SwissMicros, with many modern features: extended precision, 1000‑digit integers, graphing, rich complex support, configurable stack depth, etc.
  • It runs C47/R47 firmware on DM42n-class hardware, with a new keyboard/overlay and math code derived from WP 34S. Function set is a superset of classic HP scientifics.
  • Uses a low‑power Cortex‑M33 at up to 160 MHz and a Sharp-style memory LCD similar to the Playdate’s, powered by a single CR2032.

Nostalgia vs Innovation

  • Some commenters see it as a backward-looking tribute rather than in the spirit of HP’s original “tech‑pushing” machines (e.g., HP‑65).
  • Others are simply delighted that any new, serious RPN hardware exists at all and praise the engineering and openness.

Price, Availability, and Audience

  • Price (~300 USD / 250 “credits”) is widely noted as high; people debate who the target user is.
  • Explanation offered: small-batch production, high build quality, and an existing niche community already buying SwissMicros devices and running custom firmware.
  • Launch involved vouchers for early-bird supporters; “out of stock” early on was attributed to launch timing rather than actual unavailability.

Role of Physical Calculators Today

  • Several users still rely daily on HP-style calculators (35s, 42S, 48G/GX, 16C, TI‑89, etc.) for engineering, industrial automation, firmware work, lab environments, and financial calculations.
  • Others say they almost never touch hardware anymore because phones/laptops with Python, MATLAB, Maxima, Jupyter, etc. are more powerful, scriptable, and better for plots and large matrices.
  • Arguments for dedicated devices: instant on, distraction‑free, tactile keys, one‑handed or gloved operation, use in dusty/wet environments, easier during exams where phones or programmable calcs are banned.
  • Some comment that modern HP hardware declined in keyboard quality; SwissMicros quality is generally praised but with mixed opinions on key feel and small key size.

RPN, Features, and Alternatives

  • RPN is valued for eliminating parentheses, exploiting the stack for complex expressions, and allowing “enter numbers first, decide operations later.”
  • R47/C47 offers 4‑level display with configurable 8‑level stack; some miss “infinite” stacks from software like Free42.
  • Others prioritize CAS support and symbolic math, preferring TI‑89/HP‑48/HP Prime–class devices or computer algebra tools.
  • Numerous software emulators and apps are mentioned for those who want RPN or HP nostalgia without new hardware.