Teaching kids about computers...

Tony Duell ard at p850ug1.demon.co.uk
Thu Nov 29 15:20:50 CST 2007

> I thought the Jupiter Ace was pretty straightforward, to be honest.

The ACE used that obnoxious trick of contenting a totem pole output in 
series with a 1k resuistor against a 3-state output. If the latter was 
enabled, it drove the output signal (overriding the signal for m the 1k 
resistor), if the latter was disabled, then a totem pole drive the output.

That 'trick' is not going to be mentioned in any introductory book on 
digital electroncs (thank %deity!), so it might well cause a lot of 


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