Re: Commodore 64 (was "Re: Teaching kids about computers...")

Ensor wrote:
> OTOH At the company I worked for at the time, the beige
"wedge shaped" 
> PSUs were dropping like flies - we found them to be
HORRENDOUSLY 
> unreliable, and those were stock unmodified C64s too!
pics?  I'm not sure I recall a wedge-shaped PSU.

> The 400 and 800 used a PIA (6520/6820) with 4 bits of
each port going 
> to each joystick port. The paddle inputs (analogue in)
and triggers 
> were handled by POKEY.
Was the trigger IO, or just input?

Paddle inputs were likewise handled by 6560/61 VIC-I in the
VIC, and 
6567/69 VIC-II in the C64.  Input only for obvious reasons.

If Atari only had 4 bits per port, You could still do 8
nybbles (4 
bytes) of data and a SELect, or 2 bytes and SEL and CLK
lines with both 
ports across the two machines.  What about TI or Apple?

Jim

-- 
Jim Brain, Brain Innovations                                
     (X)
brainjbrain.com 
Dabbling in WWW, Embedded Systems, Old CBM computers, and
Good Times! 
Home: http://www.jbrain.com

Hi,

  >> OTOH At the company I worked for at the time, the
beige "wedge
  >>shaped" PSUs were dropping like flies - we
found them to be
  >>HORRENDOUSLY unreliable....

  > pics?  I'm not sure I recall a wedge-shaped PSU.

OK, look here: http://jope.fi/cbm
/cbm/c64psu.jpg.

The PSU I'm referring to is the leftmost one of the three in
that picture; 
I've always called them "wedge shaped", but I
suppose "cheese block" would 
be closer to the mark, LOL.


  >>....The paddle inputs (analogue in) and triggers
were handled by
  >>POKEY.

  > Was the trigger IO, or just input?

Just input AFAIR.

Thinking about it, I don't think the paddle inputs weren't
"real" analogue 
inputs. Rather they timed how long a capacitor took to
charge through the 
pot inside the paddle controller.


  > If Atari only had 4 bits per port, You could still do
8 nybbles (4
  >bytes) of data and a SELect, or 2 bytes and SEL and
CLK lines with both
  >ports across the two machines....

Quite, plenty of scope there too.

However, by the time I moved onto an 800XL (which only had 2
joystick ports) 
Atari had given us the PBI expansion bus which made things
vastly 
easier....though it didn't stop me soldering another 6520 on
top of the 
already existing one and using one port for a centronics
interface and the 
other to drive a UART.... 

  >....What about TI or Apple?

My knowledge of those is sketchy at best - I have a couple
of TI's and still 
have at least one Apple ][ but haven't delved into the TI
yet, nor have I 
turned my Apple on for some 10 years!


  TTFN - Pete.