Discussion:
Burrell's Mouse Card
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cb meeks
2017-10-02 18:34:38 UTC
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Has anyone got any information (schematics?) to the original mouse card that Burrell Smith designed? Not the one officially released from Apple.

I believe it basically just had a 6522 on it and not much more.

Also, does anyone have the "driver" that was written for it? From what I remember, it filled the screen except for one dot and then set the timer in the 6522 or something like that.

I would love to build one myself for the fun of it.

Thanks!
Mark D. Overholser
2017-10-02 22:43:07 UTC
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Post by cb meeks
Has anyone got any information (schematics?) to the original mouse
card that Burrell Smith designed? Not the one officially released
from Apple.
I believe it basically just had a 6522 on it and not much more.
Also, does anyone have the "driver" that was written for it? From
what I remember, it filled the screen except for one dot and then set
the timer in the 6522 or something like that.
I would love to build one myself for the fun of it.
Thanks!
Here is the Story and a Picture....
<https://www.folklore.org/StoryView.py?project=Macintosh&story=Apple_II_Mouse_Card.txt&sortOrder=Sort+by+Date&characters=Burrell+Smith>

MarkO
cb meeks
2017-10-03 14:43:30 UTC
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Post by Mark D. Overholser
Post by cb meeks
Has anyone got any information (schematics?) to the original mouse
card that Burrell Smith designed? Not the one officially released
from Apple.
I believe it basically just had a 6522 on it and not much more.
Also, does anyone have the "driver" that was written for it? From
what I remember, it filled the screen except for one dot and then set
the timer in the 6522 or something like that.
I would love to build one myself for the fun of it.
Thanks!
Here is the Story and a Picture....
<https://www.folklore.org/StoryView.py?project=Macintosh&story=Apple_II_Mouse_Card.txt&sortOrder=Sort+by+Date&characters=Burrell+Smith>
MarkO
That's actually where I got the information from. That page only really show a crude picture. It explains it uses a VIA and a flip-flop. What I was hoping to find is the schematics and possibly the driver. I think it would be awesome to preserve and build a replica of what Burrell designed.

Thanks.
Ralf Kiefer
2017-10-04 00:13:18 UTC
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Post by cb meeks
That's actually where I got the information from. That page only really
show a crude picture. It explains it uses a VIA and a flip-flop. What I
was hoping to find is the schematics and possibly the driver. I think it
would be awesome to preserve and build a replica of what Burrell designed.
I just read this article. This job can't be very complicated, IMHO. The
6522 is easy to connect to the bus. The address space is selected by
/DEVSEL.

The connection of the mouse should be the same as in the Mac
(128/512/Plus).

The 74LS74 (half of it) is a bit more complicated. Q or /Q must be
connected to a port pin of the 6522. We cannot know which one they used
in the past. So it's your decision, i.e. PA0. /PRE and /CLR are set to
high. D is connected to D0 from the Applebus. CLK should be connected to
PHI0.

The rising edge of PHI0 transfers the level of D to Q. Q can be read
from PA0.

The article mentions the problem of a slow 6502 (10 cycles per loop) and
their solution running a loop of 17 cycles ("if the loop time was
relatively prime to the display frequency ..."). The job is to find the
one and only '0' on the data bus while video scanner is on. They set the
whole screen to '1', and when vertical/horizonatal blanking is on the
pullups set the bus also to '1'.

Easy and very smart, IMHO.

- Ralf
Ralf Kiefer
2017-10-04 00:55:34 UTC
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Post by Ralf Kiefer
They set the
whole screen to '1'
... except the last pixel.

- Ralf

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