Hacker News: gdevic

New comment by gdevic in "I designed a nibble-oriented CPU in Verilog to build a scientific calculator"

gdevic — Sat, 16 May 2026 00:14:02 +0000

There is a WebAssembly version running online here, with and without debugger panel:

https://baltazarstudios.com/files/calculator-d/Calculator.ht...

https://baltazarstudios.com/files/calculator/Calculator.html

This WebAsm code is compiled using Qt and Verilator so it runs the "hardware" and its microcode inside the simple UI shell that provides the calc interface. In the debug version you can list the ucode, set breakpoints, see regs etc.

New comment by gdevic in "I designed a nibble-oriented CPU in Verilog to build a scientific calculator"

gdevic — Fri, 15 May 2026 17:17:47 +0000

The core question: how did HP's scientific calculators actually work at the gate level? That rabbit hole led to building one from scratch.

The architectural decision everything else follows from: a decimal calculator should store numbers as BCD — one decimal digit per 4-bit nibble. A standard byte-oriented CPU (Z80, 6502) fights that layout constantly. So I designed a small custom CPU in Verilog where 4 bits is the natural data width and memory is nibble addressable.

What the project covers:

- Custom CPU: Harvard architecture, 12-bit ISA, 8-state execution FSM, hardware stack guard with a FAULT state for microcode debugging

- CORDIC for trig functions, verified to 14 significant digits

- Two-pass assembler in Python (~700 lines)

- Verilator + Qt framework: same Verilog source runs in simulation, as a desktop GUI debugger, as WebAssembly, and on real hardware

- Scripting language on top of the microcode for adding functions without touching hardware

- Custom PCB (EasyEDA/JLCPCB), battery, charging circuit

Write-up: https://baltazarstudios.com

Hackaday: https://hackaday.com/2026/05/13/build-the-cpu-then-build-the...

I designed a nibble-oriented CPU in Verilog to build a scientific calculator

gdevic — Fri, 15 May 2026 17:15:58 +0000

Article URL: https://github.com/gdevic/FPGA-Calculator

Comments URL: https://news.ycombinator.com/item?id=48151237

Points: 99

# Comments: 33

New comment by gdevic in "I love Linux, but I can't quit Windows"

gdevic — Fri, 15 May 2026 17:04:00 +0000

Absolutely agree with the OP! My first Linux installation was in 1993 when I hauled dozens of floppies from my Uni back home (X-Windows was like 15 floppies?). Even remember emailing to Linus about some issue and he responded. Ever since I _wanted_ to be using Linux but was always put off for all the reasons described in that post. I wanted a nice OS so I can do my school/work/hobbies but not constantly having to work on that OS, figure out dozens of config files, brick the system etc.

At this point WSL2 is more than filling this void. I even stopped using VMWare since WSL is that good.

Porting a Qt Project (SpeedCrunch) to WebAssembly

gdevic — Sat, 15 Mar 2025 14:15:10 +0000

Article URL: https://baltazarstudios.com/porting-a-qt-project-to-webassembly-challenges-and-solutions/

Comments URL: https://news.ycombinator.com/item?id=43372674

Points: 3

# Comments: 0

New comment by gdevic in "A Chopin waltz unearthed after nearly 200 years"

gdevic — Sun, 27 Oct 2024 21:25:45 +0000

Agree. Lang Lang is all about theatrics, also.

New comment by gdevic in "How Microchips Work"

gdevic — Sun, 17 Mar 2024 07:05:48 +0000

I loved the article! Spot on and just the right depth for the article size (I am a CPU architect).

Z80 Explorer

gdevic — Sun, 19 Jul 2020 14:57:09 +0000

Article URL: https://baltazarstudios.com/z80explorer/

Comments URL: https://news.ycombinator.com/item?id=23889771

Points: 5

# Comments: 0