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PropTerm Overview


The PropTerm project is a simple ANSI color text terminal based on the Parallax, Propeller chip. The terminal uses a standard VGA/SVGA monitor for the text display and a PS2 keyboard for user input. The PropTerm supports a subset of the ANSI Terminal protocol for display control. The ANSI terminal control protocol is the closest thing to a standard for serial connected terminal displays.

Prototype ANSI terminal using Parallax Prop development board

The PropTerm was orignaly developed to provide a text terminal display for my embedded CPM system based on the Zilog EZ80 CPU. As the PropTerm project began to function as a "real" terminal I started to use it instead of running terminal software on a computer while testing my other projects. One day I connected the PropTerm terminal to my Linux computer as a console. Once I added a few extra ANSI control sequence PropTerm seamed to work as a color text display. At this point I have added as may terminal commands as the resources of the Parallax Propeller chip will allow.

Note: Under Linux you need to use the STTY program to set correct rows/columns for the terminal. Also assure that your GETTY selects the "ANSI" terminal type. To properly use the terminal under Linux a custom terminal description needs to be created. At this time I have not got around to it (a project for the winter).

The PropTerm supports the most commonly used ANSI control, escape, and sequence codes. The terminal will display all the printable ANSI characters (ANSI codes 32..127, 160..255). Each character cell has a 6 bit text color and a 6 bit background color (00RRGGBB). The default terminal software can be altered to support up to 100 characters on a line with up to 50 display lines. The font size is 8 pixels wide and 12 pixels height. Communication between the host and the terminal is handled by a Propeller chip COG reserved for that task. This allows the hardware data connection to the host to be changed without any changes to the terminal parser or the display rasterizer software.

The displayed picture is the first version of the PropTerm. To simplify software development a Parallax Propeller chip development board was used. The only hardware added to the board is a 4 wire RS232 driver, an ATMEL 128K serial eeprom and DB9 connector. When implemented in the CPM system the PropTerm will use the I/O buss of the EZ80 CPU for communication.

Further information regarding the PropTerm project can be found on various pages on this site. The ANSI Protocol page describes the PropTerm supported ANSI control sequences. The Software page provides a look into the structure and functionality of the software developed for the PropTerm project. The PropTerm Prototype page provides technical information on the prototype hardware used to develop the software for the PropTerm project.

Last Updated on Saturday, 14 March 2009 07:21