VT100: Difference between revisions

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Note that these boards need a custom cable to connect with the M100.
Note that these boards need a custom cable to connect with the M100.
    This solution makes good use of the "BCR/CASSETTE PORT TTL SERIAL MOD".
    Why? Because the serial port can be kept for file I/O while driving the
    monitor with direct TTL serial data at 57600.
    CP/M on the Model 100 also leverages this output mechanism for video.
    Please see


== The Software ==
== The Software ==

Revision as of 17:40, 18 April 2020

VT100 1.jpg


What is this all about?

When the Model 100 was released, it was offered with another product called the Disk Video Interface, which provided dual 5.25 floppy drives and ability to support an 80x25 CRT. It was well integrated with M100 OS, with several command s that extended BASIC's ability to control the CRT.

The Model 100 lends itself well to an attached terminal acting as a video adapter, and it turns out that a project provided by Geoff Graham of Perth Australia comes very close to fitting the need.

http://geoffg.net/terminal.html

This project (plus some minor extensions), combined with some disassembly and reconstruction work on Disk Basic, has yeilded a very nice external VGA video solution for Model 100!

Acknowledgements

I would like to acknowledge and thank those that have contributed to the project:

Ken Pettit - for VirtualT, and the core disassembly of Disk Basic

Philip Avery - for efforts with CP/M and attached Video using the VT100 Adapter

Geoff Graham - for the original VT100 Terminal Project


Supported Models

  • TRS-80 Model 100, Tandy 102


The Hardware

There are several sources for the VT100 Adapter. I have developed a PCB version that is, I think, most convenient for Model T users as it has a native DE-9 connector for serial data connection.

Contact me to obtain a kit for my variant of the VT100 Adapter, including the revised firmware.

Other sources are available. See http://geoffg.net/terminal.html and https://www.tindie.com/products/petrohi/geoffs-vt100-terminal-kit/

Note that these boards need a custom cable to connect with the M100.


   This solution makes good use of the "BCR/CASSETTE PORT TTL SERIAL MOD". 
   Why? Because the serial port can be kept for file I/O while driving the
   monitor with direct TTL serial data at 57600.
   CP/M on the Model 100 also leverages this output mechanism for video.
   Please see

The Software

The solution requires some software. Generally, you require 1. VT100 Driver software: stand alone equivalent of "Disk Basic" tailored for the VT100 Adapter 2. A patched version of the firmware for the VT100 Adapter, needed to enable certain M100 specific functions.

VT100 Driver

The following table has links to the current VT100 Driver software and source code.


ModelDescriptionFileRevision
M100/T102VT100 DriverVT100 Driver19
M100/T102VT100 Driver SourceVT100 Driver Source Code19


Installation:

  NOTE: installation of the driver resets the DATE and TIME on your laptop.
  1. load VT100.CO into your Model 100.
  2. Enter BASIC, and issue command
  CLEAR 0, 60000
  3. Return to MENU, cursor over to VT100.CO and hit ENTER.
  The VT100 Driver code is now installed.  You can delete VT100.CO; the code is installed in uppper RAM.
  

I recommend downloading the Disk Video Interface User Guide to learn about how the DVI commands work. The VT-100 driver is essentially replicates the functionality, with a few differences:

  SCREEN command:
  Format of command is SCREEN X,Y
  X = 0, -> LCD
  X = 1, -> CRT attached to RS-232 port, 19200 8N1
  X = 2, -> CRT attached to "the BCR/Cassette port hack", Serial TTL at 57600 bps
  WIDTH command:  not functional. CRT is pinned at 80x24.
  Also, support for printing the CRT contents to Printer is not implemented.

VT100 Terminal Firmware Update

I based the Model 100 variant of the firmware on Version 1.3 as posted by Geoff at his site. I have two files here: (1) the firmware itself, ready to load into an existing VT100 and (2) the modified project.

I followed Geoff's guidance for tools etc. needed to build the firmware.

I recommend that anyone looking to reflash an existing VT100 Adapter, please follow the instructions at Geoff's site. You do not need a programmer; you need to connection via USB to a Windows PC and run the Micrchip Bootloader application.



What is itDescriptionFileRevision
VT100 Adapter FirmwareModified V1.3 firmware / M100 support VT100 Firmware19
VT100 Adapter ProjectModified V1.3 Project files/ M100 support VT100 Terminal Project19