Computers for children

From: dave dameron <ddameron_at_earthlink.net>
Date: Fri Jan 15 00:14:40 1999

Hi Tony and all,
At 10:44 PM 1/14/99 +0000, you wrote:

>I would strongly disagree with that, at least in hardware. I've recently
>been looking at some discrete-transistor logic circuits and the
>creativity that went into their design (IMHO) exceeds anything that I've
>seen done with modern 'black-box' chips. For example, I've seen a
>keyboard encoder (8*8 matrix of keys to 6 bit binary + strobes + ...) in
>about 20 transistors and as many diodes. Much, much more elegant than
>throwing a microcontroller at it.
>
Yes, for example the Popular Electronics keyboard in ~1974 by Don Lancaster
and Southwest Technical Products used a few inverters (RTL) and transistors.
3 transistors sensed which of 8 columns a keyswitch was pressed, and these 3
transistors produced 3 of the ASCII output bits. The 8 row ouyputs produced
3 other bits. Much easier to "fix" than the MOS encoder chip, if that chip
was programmed for a custom matrix, such as the Heath H19 terminal.
-Dave
Received on Fri Jan 15 1999 - 00:14:40 GMT