Larry's Blog

ALPHANUMERIC DISPLAY AND KEYBOARD

Do you realize you can pick up older keyboards for one dollar! I have a few and use them to interface with my computer chips. I have done more work on my alphanumeric LCD (liquid crystal display). I can now set addresses and send ascii characters to these locations. The lcd controller automatically increments or decrements, each time you write to an address.

I am now able to read the contents of the DD RAM. The bytes of this memory correspond to the characters appearing on the display. The character generator is transparent to the programmer and produces the pixels that form the characters displayed. A very interesting development is serial rather than parallel LCDs. These seem to cost
$45 and up whereas the parallel type go for 10 to 20. It is desirable to have LED backlighting for good visibility.

SONG MAKING CIRCUIT

Here is a version of a circuit that plays music. The program actually calls subroutines called doe,ray,me,far,sew,la,tea,doo. I have done lots of pgms on generating sounds, but this one attempts to get accurate mnotes of the musical scale. Some of the ideas came from an artice by G. Y. Xu in Nuts & Volts magazine.
So far this circuit plays Westminster Chimes and the theme played a race tracks for the start of the race. My circuit plays the notes as regular tones or as bell chimes.