63 lines
2.4 KiB
Markdown
63 lines
2.4 KiB
Markdown
---
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layout: post
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title: The VT100 Terminal
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date: 2016-08-03 18:00:00
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permalink: /blog/2016/08/03/
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machines:
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- type: pc8080
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id: vt100
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config: /devices/pc8080/machine/vt100/machine.xml
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---
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Summer has been filled with distractions, but I've finally begun making headway on a
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[DEC VT100 Terminal](/devices/pc8080/machine/vt100/) simulation.
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Unlike other VT100 emulators, this isn't simply an emulation of VT100 protocols. It's a simulation of the VT100's
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8080 CPU, running the original [VT100 Firmware](/devices/pc8080/rom/vt100/) inside the [PC8080](/modules/pc8080/)
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CPU emulator, along with other key components that the CPU interacts with to drive the display, keyboard, and serial port.
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It's not fully operational yet, but as you can see below, major pieces are falling into place, including a test screen that
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displays most of the VT100 font variations, built on-the-fly from the original VT100 Character Generator ROM, and LEDs that
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respond to the firmware's commands. When the VT100 "powers on", it briefly displays a "WAIT" message as it processes the
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VT100's Non-Volatile RAM (NVR), and then it spins, awaiting further stimulus.
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{% include machine.html id="vt100" %}
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Function keys are mapped as follows:
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- F1: PF1
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- F2: PF2
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- F3: PF3
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- F4: PF4
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- F6: BREAK
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- F7: LINE FEED
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- F8: NO SCROLL
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- F9: SET-UP
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From the SET-UP screen, you can press **4** to switch to LOCAL mode and verify local operation of most VT100
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keys. The following keys have special meaning inside SET-UP Mode:
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- 0: RESET
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- 2: SET/CLEAR TAB
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- 3: CLEAR ALL TABS
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- 4: ONLINE/LOCAL
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- 5: SET-UP A/B
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- 6: TOGGLE FEATURE
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- 7: TRANSMIT SPEED
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- 8: RECEIVE SPEED
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- 9: 80/132 COLUMNS
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- SHIFT-S: Save SET-UP Features
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- SHIFT-R: Restore SET-UP Features
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The initial goal for the simulation is to provide a virtual terminal that can communicate with other PCjs machines
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and provide a realistic serial communication experience, all from the comfort of your web browser.
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There's still plenty of debugging to do, because while DEC's Technical Manuals were excellent, they were
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not comprehensive; there are no commented source-code listings, for example, like those that IBM used to provide in their
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early Technical Reference manuals, so we have to [create our own](/devices/pc8080/rom/vt100/).
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Check out the [VT100 Debugger Configuration](/devices/pc8080/machine/vt100/debugger/) for additional information about
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VT100 internals and links to other technical resources.
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*[@jeffpar](http://twitter.com/jeffpar)*
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*Aug 3, 2016*
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