# NetISA

NetISA is a design for an 8-bit ISA card that gives DOS PCs modern HTTPS, with WiFi and TLS on an ESP32-S3. Design stage, not built yet.

Source page: https://barelybooting.com/netisa/

<p class="status-line"><strong>Status:</strong> Design stage. Not built. Paused since August 2026.</p>

It's not dead. It's resting.

NetISA is my design for an 8-bit ISA card that would let a DOS PC reach modern HTTPS websites. An ESP32-S3 on the card does the WiFi and the encryption, so the old CPU never has to do any of the heavy maths. As far as the PC knows, it's just talking to a few I/O ports through a small TSR.

## Why I want one

Modern encryption is a lot to ask of a vintage CPU. Other people have come at the problem in clever ways. [Crypto Ancienne](https://github.com/classilla/cryanc) and [WinGPT](https://www.dialup.net/wingpt/tls.html) run TLS on the old machine itself, [PicoMEM](https://github.com/FreddyVRetro/ISA-PicoMEM) gives ISA PCs WiFi by pretending to be a network card, and [FrogFind](https://github.com/ActionRetro/FrogFind) and [Browservice](https://github.com/ttalvitie/browservice) put a modern computer in the middle. My idea is to put the encryption on the card instead, so the PC only ever deals with plain text.

## What exists right now

So far it's a design, some code and a pile of parts. The logic that talks to the ISA bus runs in simulation, and the DOS side (the TSR and a little launcher) runs in the DOSBox-X emulator against a stand-in for the real card. The parts showed up in April 2026. Nothing has been built, powered up or tested on real hardware yet.

<figure>
<a href="/img/netisa-parts-arrival.jpg"><img src="/img/thumb/netisa-parts-arrival.jpg" alt="Anti-static bags of components, capacitors, resistors and a yellow 8-bit ISA prototype board spread on a wooden bench" width="320" loading="lazy"></a>
<figcaption>The NetISA parts, April 2026. <a href="/img/netisa-parts-arrival.jpg">Full size</a> (317 KB).</figcaption>
</figure>

The tools doing the work so far, with thanks to the people behind them: Espressif's [ESP-IDF](https://github.com/espressif/esp-idf) for the card's firmware, [Icarus Verilog](https://steveicarus.github.io/iverilog/) for simulating the bus logic, Intel's Quartus II for fitting it to the CPLD, [NASM](https://www.nasm.us/) and [Open Watcom](https://github.com/open-watcom/open-watcom-v2) for the DOS side, and [DOSBox-X](https://dosbox-x.com/) for running it all before there's a card to run it on.

More when it's built. If it ever powers up, you'll read about it here first.