1351 again

From: Levente Hársfalvi (Levente_at_terrasoft.hu)
Date: 1999-09-28 21:31:57

Hi all!

Thanks to Frank Kontros, I got answer for my questions concerning the
1351 device.

For a final test, I'd like to ask some of you owning 1351 mice. This
could be a good feedback for me if my thoughts are right at least in

(Base info: the clock of the C64 is slightly off from 1Mhz, which is the
nominal frequency of the 1351. This should cause small differences in
the range of the transmitted position data to the POT registers.)

I'd like to ask at least two people - one with a PAL and one with an
NTSC C64 - for this test. What I'm interested of, is the actual range of
the position data appearing in the POTX and POTY registers. This can be
measured by the following way: switch the computer on, write a small
program that first initializes a min variable to 255, a max to 0, then
keeps on watching the SID POTX register and compares the resulting
values to min and max. When it is less than min, min:=value, if it is
more than max, max:=value. After running the program, slowly move the
mouse for a while. After that, check min and max. These are the values
I'm interested of.

(I can write and send the tester if somebody wants to help me but don't
want to fiddle with coding).

In theory, both computers should give values between 64 and 196, the PAL
machine slightly few (...about 59-188), the NTSC more (71-202).

I'm also interested if anybody could confirm that an American 1351 has
slightly smaller resistor on the POT lines (the one I know whose
schematics were drawn by Frank has 5.1k). This is just a suspect. A
resistor like that results in an additional delay of 5-6 cycles on the
POT lines which is O.K. for the PAL but really not wanted for the NTSC

Thanks a lot...


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