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Updated VT100 blog post

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Jeff Parsons 2016-08-17 16:04:20 -07:00
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_posts/2016-08-03-the-vt100-terminal.md
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@ -14,12 +14,16 @@ Summer has been filled with distractions, but I've finally begun making headway
Unlike other VT100 emulators, this isn't simply an emulation of VT100 protocols. It's a simulation of the VT100's
8080 CPU, running the original [VT100 Firmware](/devices/pc8080/rom/vt100/) inside the [PC8080](/modules/pc8080/)
CPU emulator, along with other key components that the CPU interacts with to drive the display, keyboard, and serial port.
CPU emulator, along with other essential components that the CPU interacts with to control the display, keyboard, and
serial port.
It's not fully operational yet, but as you can see below, major pieces are falling 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 the VT100 "powers on", it briefly displays a "WAIT" message as it processes the
VT100's Non-Volatile RAM (NVR), and then it spins, awaiting further stimulus.
Most of the VT100's (non-AVO) functionality should be operational now. The VT100 screen is initialized with a test
image that displays most of the VT100 font variations, built on-the-fly from the original VT100 Character Generator ROM.
Once the VT100 "powers on", it should clear the screen and briefly display a "WAIT" message as it processes its Non-Volatile
RAM (NVR). When you see a blinking cursor, it's ready to use. Press the SET-UP key to configure the terminal, just as you
would an original VT100 terminal.
For even more fun, check out the [Dual VT100 Terminals](/devices/pc8080/machine/vt100/dual/) demo.
{% include machine.html id="vt100" %}
@ -52,9 +56,10 @@ keys. The following keys have special meaning inside SET-UP Mode:
The initial goal for the simulation is to provide a virtual terminal that can communicate with other PCjs machines
and provide a realistic serial communication experience, all from the comfort of your web browser.
There's still plenty 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, so we have to [create our own](/devices/pc8080/rom/vt100/).
Eventually, I would also like to recreate a fully commented source-code listing for the [DEC VT100 ROMs](/devices/pc8080/rom/vt100/).
DEC's [VT100 Technical Manuals](/pubs/dec/vt100/) are excellent, and they provide an enormous amount of hardware detail,
but they are a bit light on certain programming details, and there are no firmware listings like those those that IBM provided
in the early IBM PC Technical Reference manuals.
Check out the [VT100 Debugger Configuration](/devices/pc8080/machine/vt100/debugger/) for additional information about
VT100 internals and links to other technical resources.