Remapping the HP150 keyboard

Rik Bos hp-fix at
Fri Apr 17 16:16:54 CDT 2009

How about KISS (keep it smart and simple).
Smart for the idea and simple for the building, exactly what you did in my
humble opinion.
The use of the 4000 cmos series is in line with the engineering of the
And like you said HP150 keyboards are 'easy' to find ;-)


> -----Oorspronkelijk bericht-----
> Van: cctalk-bounces at 
> [mailto:cctalk-bounces at] Namens Tony Duell
> Verzonden: vrijdag 17 april 2009 19:39
> Aan: cctalk at
> Onderwerp: Re: Remapping the HP150 keyboard
> > > I;'d love to see you fit anything into the connector of 
> an HP120 or 
> > > HP150 keybaord. The connnector, BTW, is a 6 pin RJ11....
> > 
> > Okay, then how about fitting one inside of an RJ25 (isn't that a 6- 
> > pin RJ11?) "crossover" adapter?
> What good would that do? This is not an interface module that 
> connects between the HP120 and an unmodified HP150 keyboard 
> (if it was, I wouldn't have bolted it to the keyboard, cf the 
> interface for the 262x keyboard I described last week). It's 
> a modification to the HP150 keyboard tht electrically 
> connected by a piece of 14 way ribbon cable and a DIL header 
> in place of a 4024 chip on the keyboard PCB (Desolder the 
> chip, solder in a socket. P,ug in a 4024 to return the 
> keyboard to the original HP150 circuit, or this modification 
> board to make it work with either the HP120 or HP150).
> Making an interfaec to connect between the HP120 and an 
> unmodified HP150 keyboard would be a lot harder (and would 
> almost certainly need a microcontroller). You'd have to scan 
> the HP150 keyboard (generate clock and reset pulses, grab the 
> state of the keydata line), then store the state of all the 
> ekys and transmit them to the HP120 in accordance with the 
> clock and reset pulses from that machine. 
> I did consider doing this, but the modification to the 
> keyboard turned out to be a lot easier.
> -tony

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