Original PET Keys

From: Larry Anderson <foxnhare_at_goldrush.com>
Date: Mon Dec 7 20:43:10 1998

> From: Doug Spence <ds_spenc_at_alcor.concordia.ca>
> Subject: Re: PET Video (was: Replacing 6550s) & 128

> > > ::"chiclet keyboard" != "rubber keys", IMHO. I'm talking about the cute
> > > ::multicoloured keyboard with the small plastic keys that are arranged in a
> > > ::grid pattern. I call that a chiclet keyboard.
> > >
> > > Hmm, okay. But multicoloured? Which colours? Arranged how?
> >
> > Ummm they were all metallic tops, Red, Gold, Blue, Silver... Check out my
> > PET page:
>
> Gold? Your PETs have gold keys? I have two shades of blue. And my red
> keys look significantly less metallic than the others. I couldn't tell if
> they were 'metallic' or if I was looking at the nail polish my brother
> coated the keys with to keep the printing from rubbing off.

Maybe I'm mistaken about the gold ones, (that PET is currently back in
storage)... Fortunately I was given a spare set of by a friend who serviced
PETs and also once worked at Commodore (he also wrote the original PET uers
guide and some of the diagnostics, I had him sign my users guide) but so far
the original set on the PET haven worn all that much yet (the previous owner
was very good to that machine).

0001010010110101010101000101000111000110010010

> From: Doug Spence <ds_spenc_at_alcor.concordia.ca>
> Subject: Re: Replacing 6550s
>
> > > Actually, IIRC my small-keyboard PET uses little rubber cups. But I
> > > suppose there may be springs as well. The keyboard didn't work when I got
> > > it, so I had to disassemble it and wipe the circuit board clean. I never
> > > disassembled it beyond pulling the circuit board off.
> >
> > No rubber cups. Rubber cups or domes always in my experience give some
> > sort of mechanical hysteresis when you press them. All PET keyboards I've
> > used are smooth until they hit the stop. Small keyboard had little black
> > rubber pads set into the plastic mouldings of the keys.
>
> I think there are rubber cups of some sort, but they may be soft
> protective things rather than what provides the 'bounce'. I just tried
> both PET keyboards and compared the feel to other keyboards, and you're
> right, they are smooth. Potential 'rubber cup' keyboards: CoCo 1, Amiga
> 3000. Weird undefinable keyboard that mushes/springs at the bottom: Atari
> 130XE. :)

The Calculator PET cups (which my keyboard has) are not all that deep, so you
would not feel the 'mechanical hysteresis' you were describing, they act as
the 'spring' I am sure. The large keyboard PETs used springs but later some
VIC-20s had cups again... strange... :/

> Where would you put ROM expansion? There's no empty sockets in this model
> PET.

With the ExpandaPET board you have I think 4 KIM bus slots, I have a couple
cards for one, one is an EPROM board and the othersome sort of floppy
controller (they probabably worked together)

> > > Why do POKE and PEEK fail there? Was that done on purpose or is it just
> > > the result of something lame like using a signed value to represent
> > > addresses?
> >
> > No, it's software. It was a feature that was supposed to prevent
> > inquisitive geeks disassembling the BASIC ROM between $C000 and (I think)
> > $E7FF. The OS ROMs, above $F000, were peekable, though, as was the I/O
> > space in the E block. You could of course peek and poke the screen, $8000
> > - $83E7 inclusive.
>
> An inquisitive geek wouldn't be stopped long by that! Bill should have
> known better. :)

All you had to do was poke in an ML byte transfer routine...

That 'bug' was corrected in the upgrade ROMs (good move on Commodre's part, by
opening access and info on the system more people devloped for it.) as well as
in the realase of the monitor program. Other companies who tried such stingy
tactics (Atari early on and most certainly TI) were really hurt by it.

> > I'll try and dig out my RAM expansion board, and work out what it did.
> > Meanwhile, have fun!
>
> No fun until all my assignments and exams are done. :/
Received on Mon Dec 07 1998 - 20:43:10 GMT