|
Alexander Shabarshin (Bethpage, New York)
Text module 80x25 for NTSC televisions
 |
|
Click on Image for a close-up
|
Downloads for this project:
All files and information © 2006 Alexander Shabarshin.
Project Description:
 |
|
Click on Image for a close-up
|
This device generates standard NTSC video signal with 80 x 25 characters (6 x 8 pixel each) from range 0x20...0xEF (ASCII and alternative DOS codepage CP-866 with pseudo-graphics). It can be used as black-and-white text display for other microcontroller devices. Display has 25 lines each consisting of 80 characters (white characters over black background) - 2000 visible characters total. It is readable even on cheap $20 portable TVs.
Data input is simple 11-wire parallel interface: 8 data, 2 control and 1 ground. Along with characters codes interface supports 2 command: 0x01 N to set current column and 0x02 N to set current line. For testing purposes LPT-port may be used.
Images of characters are lashed to SX chip as part of program memory. External 2K 70ns SRAM is used as video memory. External shift register (Parallel- In/Serial-Out) is used to generate video signal.
 |
|
Click on Image for a close-up
|
Module may be used as part of other larger projects: VT52 terminal emulator for *nix; DOS or CP/M-80 emulators; text overlay over NTSC (device can be reprogrammed to be driven by external horizontal and vertical clocks). PAL video standard can be used too (program modification is required).
|