Designed for RC2014


I first tweeted about the VT132 in March 2019 I had put together a first prototype in time for mVCF - Melbourne (AUS)


Back then it was simply the hardware implementation of the brilliant work done by Fabrizio Di Vittorio in creating the FabGL library for the ESP32. An ANSI/VT compatible, serially connected terminal with VGA output and a PS/2 keyboard.

But I wanted to extend his work and make a very authentic implementation of the DEC VT100 down to every reasonable detail.

Clearly from the prototype I'd already chosen the form-factor to be a "Designed for RC2014" expansion card for the RC2014 bus.

I then took a break from the VT132 while I worked to finish another little project - the IMSAI 8080 replica

In January 2020 I again tweeted about the VT132 because I'd started to play around with it once more.

I'd added most of the authentic VT100 features I could think of, and decided that since the ESP32 has lots of UARTS and WiFi, that I would include a Telnet over WiFi, AT (Hayes) style modem on a second UART. I'd already developed the modem code for the IMSAI8080 replica, so it was easy to integrate it into the VT132.

This is where the fun/trouble began...

  • FabGL is an Arduino library. Running FabGL @ 800x600 native resolution (800x300 scanline doubled) consumes a lot of the ESP32s internal memory.
  • Turning on WiFi in the Arduino environment on an ESP32 also consumes a lot of the ESP32s internal memory.
  • Moving to the ESP32-WROVER with 8Mb of SPRAM helps a little, but it's still the internal memory that is the limiting resource.
  • The Arduino IDE for ESP32 doesn't let you control and fine-tune all the memory and network resource allocation like the ESP-IDF does.
  • But Espressif thought of that...
    • It is possible to run the Arduino library as a component in the ESP-IDF environment.
    • I was easily able to make FabGL behave as an ESP-IDF component too.

By April 2020 I was able to start posting videos to YouTube showcasing the features of the VT132.


In June & July 2020 I conducted a closed Beta program with some fantastic people from the Retro-computer community. Their contribution to improving the VT132 and accelerating the development, ready for production has been invaluable.

In July 2020 the VT132 began shipping to the patiently waiting early-adopters.


VT100 Terminal

The VT100 Terminal:

  • connects to the RC2014 over the Tx/Rx lines (Pins 35 & 36) of the RC2014 Bus
  • takes power from the bus from Gnd/5V (Pins 17 & 18)
  • fully DEC VT100 Escape Code compatible
    • extended escape code support from other DEC VTxxx models
    • extended ANSI.SYS escape code support
    • to be detailed on another page (tba)
  • 800x600 native resolution over VGA (DB15 connector) - actually 800x300 with scanline doubling
    • 800x240 viewport in 24 line (native) mode
    • 800x250 viewport in 25 line (enhanced) mode
    • 800x300 viewport in 30 line (enhanced) mode (excludes the use of Wi-Fi because of memory constraints)
  • 10x10 character cells in 80 column mode
    • original DEC VT100 font (ASCII 7-bit) with pixel stretching as per the original VT100 hardware
    • original DEC Special Graphics overlay font (inc. line drawing characters)
    • original DEC VT220 Multinational Character Set (MCS) font (8-bit)
    • DEC National Replacement Character Set (NRCS) support (7-bit) (from VT220)
      • implemented for US/UK/Germany/Italy, other countries to follow
    • PC/VGA Code Page 437 font for ANSI.SYS compatibility
      • supports DEC Special Graphics mapping to CP437
      • supports NRCS mapping to CP437
  • 6x10 character cells in 132 column mode
    • modified DEC VT100 font (ASCII 7-bit)
    • modified DEC Special Graphics overlay font (inc. line drawing characters)
    • modified DEC VT220 Multinational Character Set (MCS) font (8-bit)
    • DEC National Replacement Character Set (NRCS) support (from VT220) see above.
    • no CP437 support in 132 column mode
  • accurate Smooth Scrolling (requires XON/XOFF as per the original VT100 to avoid dropped characters)
  • interlace/non-interlace mode (simulated: doubled scanlines are either hidden or drawn)
  • PS/2 Keyboard (Mini-DIN 6, PS/2 connector)
    • supports keyboard layouts for US/UK/Germany/Italy, other countries to follow
  • implements all VT100 Advanced Video Option (AVO) features
    • 132x24 (native), 132x25 & 132x30 (enhanced) character resolution
    • additional character attributes - Bold, Blink, Underline, Reverse (and combinations)
    • additional character ROM (NRCS and MCS fonts)
  • implements user programmable answer back as per VT100
  • implements a physical buzzer on the PCB for
    • keyclick
    • bell (^G)
    • margin bell
    • NVRAM error notification
    • non-blocking (operates on a timer interrupt and does not block serial communications)
  • implements 16 colour support
    • complies with ANSI escape code selection
    • use selectable default text and background colours via additional Set-up C screen
  • full VT100 style Set-up screen implementation
    • Activated by Alt-SysReq key-press (usually Alt-PrintScreen)
    • Set-up A (native as per VT100 with minor modifications)
      • added 'T' command to restore default Tab-Stops (from VT102)
    • Set-up B (native as per VT100 with minor modifications)
      • added 'C' command to clear NVRAM
      • 50/60Hz bit replaced by Backarrow Key Mode selection bit (DECBKM)
      • added selection of how Bold font is represented (bright &/or double-thick)
      • added selection of ANSI.SYS mode compatibility
      • baud rates supported - 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200
      • fixed serial format 8N1, no current support for 7 bits, parity or 2 stop bits
    • Set-up C (enhanced) enables:
      • DEC/VT font or CP437 font selection
      • 24 line (native) / 25 line / 30 line (enhanced) mode selection for ANSI compatibility
      • default foreground text colour selection, 1 of 16 colours
      • default background colour selection, 1 of 16 colours
      • ANSI or VGA 16 colour palette selection
    • Set-up D (enhanced) enables:
      • 7-bit ASCII (native) / 8-bit MCS selection (enhanced)
      • 7-bit NRCS country selection
      • keyboard country/language selection
      • personality selection
        • personality (escape code and keyboard code translation) support for:
          • ANSI/VT100, ADM-3A, ADM-31, Hazeltine 1500, Osborne 1, Kaypro, VT52
          • WordStar/VT100 - VT100 terminal with WordStar navigation keys for compatibility with many CP/M applications
          • details on the Setup-D screen
    • all Set-up screens include optional help by pressing 'F1' key (enhanced)
  • Quick Menu system (modeled on the VT510 setup menus)
    • Activated by LeftAlt-Esc key-press
    • Provides quick access to:
      • common actions, eg. clear screen, reset, reboot, clear NVR
      • terminal personality selection
      • MCS/NRCS mode selection
      • macros for ASCII modes including:
        • Green/Amber/Blue/White screen emulation
        • ANSI.SYS mode compatibility
      • keyboard country/language selection
      • modem locally connected mode (direct VT100 to modem connection)
      • online/local mode selection
  • Non-volatile Storage (NVRAM) support for all terminal settings
    • save settings function - 'S' in Set-up screens
    • restore settings function - 'R' in Set-up screens
    • settings are restored on reset and power-up
  • a 6-pin FTDI header with dedicated UART for firmware flashing and for debug log monitoring

Full details of configuring the terminal via the Set-up screens is covered in the VT100 Operator Information Manual

Telnet/WiFi AT (Hayes) Modem

The Telnet/WiFi AT (Hayes) Modem:

  • connects to the RC2014 over the Tx2/Rx2 lines (Pins 35 & 36) of the RC2014 Enhanced Bus
  • takes power from the bus from Gnd/5V (Pins 17 & 18)
  • implements a minimal set of 'AT' commands enabling it to behave as a serially connected modem
  • supports storing all 'S' register settings in non-volatile storage (NVRAM)
  • settings can be restored from NVRAM or restored to 'factory' defaults
  • settings are restored from NVRAM on reset and power-up
  • support 'DIAL' mode for outbound connections to hosts
  • supports 'ANSWER' mode for inbound connections including simulated 'RING' cycle
  • does not aim to reproduce every feature and command of any specific Hayes modem
  • connects to a WiFi access point over 2.4 GHz (802.11 b/g/n) as a WiFi station (STA mode)
  • cannot currently act as a WiFi access point (AP mode) - but this would be possible if it is a feature that people want
  • supports Telnet and TCP socket protocols for connecting to hosts
  • supports serial baud rates of 4800, 9600, 14400, 19200, 38400, 57600, 1152000 from the UART
    • making it compatible with all the speeds of the RC2014 Dual Serial Module SIO/2 or similar
    • does not currently support 'autobaud'
      • but is selected by the 'Prog' press button switch on the PCB
      • the chosen speed is stored in NVRAM and persists through resets and power cycling
  • supports CTS/RTS hardware flow-control over a 6-pin modified FTDI style modem header (not the RC2014 Enhanced Bus)

A full list of the 'AT' command set implemented and details of all the 'S' registers and their use is covered in the 'AT' (Hayes) Serial Modem Operation Manual

Over-the-Air (OTA) Firmware Updates

  • Firmware updates are hosted on GitHub
  • The current production firmware (V1.0.0) can always be found at github.com/thehighnibble/vt132/releases/latest
  • OTA Updates can be performed directly from the VT132 over Wi-Fi with only power, a VGA monitor and PS/2 keyboard connected, no connected RC2014 or PC is required

The process for OTA Updates is covered in the OTA Firmware Update Guide


The VT132 is currently available (since July 2020) and has a price of USD$50. In addition to this you must pay for shipping and any transaction fees. Payment is via PayPal.

To Order

I am accepting orders via email. If you send email to info@thehighnibble.com with your shipping name & address, I will respond to you with a PayPal invoice with the total price including shipping and transaction fees.


Please only pay against the PayPal invoice when I send it to you. Do not try to pay directly to me via PayPal as this will only delay your order.


Dimensions (built)

Designed for RC2014

Conforms to standard RC2014 card dimensions

Weight (built)

0.1 lbs

0.045 kg


5VDC @ 500 mA (max., < 100mA typical) - Powered from RC2014 Bus or via FTDI or Modem connectors (jumper selectable).

Dimensions (boxed/shipped)

7 1/2" x 5.5" x 2"

190mm x 140mm x 50mm

(width x height x depth)

Weight (boxed/shipped)

less than 0.44 lbs

less than 0.2 kg


Operation Manual

Last Updated: 7/26/2020, 4:34:14 PM