7 Dec
1998
7 Dec
'98
3:43 p.m.
From: Doug Spence <ds_spenc(a)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: From: Doug Spence <ds_spenc(a)alcor.concordia.ca>
Subject: Re: Replacing 6550s
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... :/
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. 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. 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. :/