This is David Murray's latest hack.. It is a Hummer DTV board placed inside a Jiffybox with a standard HD44780 LCD screen. It is a 20x4 character screen with an LED backlight. It is connected to the user port and he has written special software which copy's the C64's text screen to the LCD like a virtual window. It runs from the interrupt routine so it will allow you to use most regular text software without modification. The driver is stored in flash memory, so no disk drive is required to power the unit on and use the LCD. The LCD can also be used independently of the main video output giving it, essentially, dual monitors.

This is a remake of a previous hack I did, but I built this from scratch. Some things I did to this unit that I have never done before are:

  • Used a square LED which fits flush with the plastic.
  • The LCD screen is mounted flush with the plastic, so at some point I can put some kind of cover on the top side.
  • All of the connections on the inside can be connected and disconnected, for ease of working on it.
  • It has 3 buttons on the front panel which connect to the Hummer's 3 joystick lines. They will, at some point, operate menus on the LCD screen.
  • The reset button on the back also connects to the reset line on the IEC port, so it resets the DTV and the disk drive(s).

    Click here for the schematic of just the LCD, with LCD specific information.

    Click here for the schematic of the entire project. (If you can't see these properly, you may need to turn off "Automatic Image resizing" in Internet Explorer. Or just save the file to your harddrive and view it with a program other than IE.

  • LCDTEST.PRG - A test-program written purely in BASIC.
  • LCD.PRG - Library of commands written in ML, also includes interrupt driven screen-copy.
  • LCD.ASM - Source code to above.

    For the BASIC program, you must first use Option #5 to set 4-bit mode. Then option 4 to enable display. I recommend this for testing the display.

    For the ML program, you can start the entire process by SYS 49479. However, it only copies the bottom four lines of your screen so if there isn't anything there, it might appear not to be working. The latest version also scrolls like a virtual screen left-to-right as it follows the screen cursor. So the entire 40-columns are available. However, it does not scroll up and down. Also, this program is designed for a 4-line LCD. It would work with a 2 or 1 line LCD with only small modifications.

    Here is the schematic for the daughter board I created. All the blue wires shown are connecting somewhere to the DTV board.

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