1.9 KiB
| layout | title | date | permalink | machines | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| post | The VT100 Terminal | 2016-08-03 18:00:00 | /blog/2016/08/03/ |
|
Summer has been filled with distractions, but I've finally begun making headway on a DEC VT100 Terminal simulation.
Unlike other VT100 emulators, this isn't simply an emulation of VT100 protocols. It's a simulation of the terminal's 8080 CPU, running the original VT100 Firmware inside the PC8080 CPU emulator, along with other key components that the CPU interacts with to drive the display, keyboard, and serial port.
It's not operational yet, but as you can see below, pieces are starting to fall into place, including a test screen that displays most of the VT100 font variations, built on-the-fly from the original VT100 Character Generator ROM, and LEDs that respond to the firmware's commands. When you start the simulation, it briefly displays a "WAIT" message as it processes the VT100's Non-Volatile RAM (NVR), and then it spins, awaiting further stimulus.
The initial goal for the simulation is to provide a virtual serial terminal that can communicate with other PCjs machines and provide a realistic serial terminal experience, all from the comfort of your web browser.
In the interim, there's still a lot of debugging to do, because while DEC's Technical Manuals were excellent, they were not comprehensive; there are no commented source-code listings, for example, like those that IBM used to provide in their early Technical Reference manuals. I also plan to increase the resolution of the font rendering, so that the characters look more like the original VT100's, with its discrete glowing dots.
{% include machine.html id="vt100" %}
@jeffpar
Aug 3, 2016