[net.micro.cbm] C-65 PRG Updates > correction<

garyh@iddic.UUCP (Gary Hanson) (01/15/85)

?REDO FROM START
 
Re: my previous article <1902@iddic.UUCP> C-64 Programmers Ref Guide Updates:

  I was just checking the stuff about the joystick ports (page 343), and
got hopelessly confused trying to figure out what was where exactly. So,
apparrently did Commodore's beleagured writers, who stumbled badly here.
Anyway, I checked the schematic and discovered the following: Control Port
1 (ie. joystick port 1) has signals like POTAX and POTAY, and JOYA0 - JOYA3,
which go to -> PORT B <- on CIA #1. Likewise, Control Port 2, with its JOYBx
signals, goes to PORT *A* on CIA #1. If I were to hazard a guess, perhaps the
ECB designers told the hardware people that the board would be much cleaner
if the port assignments were swapped (from making sense), so the change made it
to some of the documentation, but not all of it, leaving it a bit of a mess.
So, I've checked the hardware, software, and documentation, and present a new,
corrected fix to the original posting. Just remember:
 
   outside         inside
   =======         ======
 
JOYSTICK PORT 1 =  CIA #1 Port B
JOYSTICK PORT 2 =  CIA #1 PORT A
 
Ignore the signal names in the schematic. With all that in mind, in the original
(more-or-less) format-- the following changes to the prior list.
 
Page  Type  Description
====  ====  ===========
 
 328   B    Location $DC00: cross out 'Light-Pen' in the description, change
            'Joystick A' to 'Joystick 2' at descriptions for bit 4 and bits 3-0.
            Also, on location $DC01, add 'Light-Pen' to the general description,
            and in the description for bit 4, add 'Light-pen'.
 
 343  B/E   A light pen (using VIC chip lightpen input) can only be plugged
            into 'Port 1 (CIA port B)' not 'Port A'. also, append to the
            second paragraph 'CIA port A = joystick port 2, CIA port B =
            joystick port 1.' Finally, you might add a picture of the bits here
            and/or on page 328 (like this, but better:)
 
            F  R  L  D  U        (fire, right, left, down, up)
            -  -  -  -  -
            4  3  2  1  0        ( bit numbers in the port data)
 
 
 -<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-<+>-
 
      Gary Hanson   Tektronix IDG   ...tektronix!iddic!garyh
 
>Dear Lisa and Mac; Sorry, no mice allowed in my house; that's why I have a cat.