3b1 Mouse needed

24 views
Skip to first unread message

J Booth

unread,
May 11, 2021, 1:09:16 AM5/11/21
to
Does anyone have a spare 3b1 mouse? I am in need of one. Alternatively, I've been trying to inject some serial data packets into the RX line of the mouse port at 1200 baud (which should go to the 6850 ACIA chip), but haven't succeeded yet. But I did get the mouse cursor to pop up on-screen. And occasionally moves. I'm pretty sure I have the data packets close to what they need to be but not 100% sure on the wiring. Anyway, if I figure it out, I'll be sure to share. But would be nice to have a real mouse for reference!

J Booth

unread,
May 11, 2021, 2:58:48 AM5/11/21
to
Well, I shocked myself and figured it out. The serial data line needs to have inverse polarity. Fortunately the softwareSerial feature in Arduino lets you invert the logic which did the trick! In the 3b1 6850 wiring, there are these schmitt trigger inverters on the RX and TX lines which made me wonder if the RX and TX lines were inverted... sho enough. So now I've got a PS/2 mouse driving the 3b1 =) Thanks again AJ for the 3b1! And for forcing me to figure this out so now maybe I can hook up a trackball for fun

Peter Schmidt

unread,
May 11, 2021, 7:07:54 AM5/11/21
to
Hah! Very cool, link to pic needed. (Or in old-school USENETese, "GIF! GIF! GIF!" ;-)

J Booth

unread,
May 18, 2021, 2:57:18 PM5/18/21
to
Finally made a dumb video of the ps/2 mouse on the 3b1: https://www.youtube.com/watch?v=Fzrrt4JAhPc
Need to learn how to use kicad so i can make a tiny board with a ps/2 port and some headers to run wires to the 8-pin mouse port -- and then plug that into an Arduino Nano. That's the current plan...

Aharon Robbins

unread,
May 20, 2021, 2:27:47 PM5/20/21
to
Nice video.

FYI, that's a Unix PC / 7300 that you have, not a 3B1. You can tell
because the case doesn't have the extra square hump to hold a full
height hard drive. The 7300s had room only for the smaller, half-height
drives, and I think came with less memory on the motherboard. Otherwise,
they were the same system.

In article <52d5ea70-12e3-4e27...@googlegroups.com>,
--
Aharon (Arnold) Robbins arnold AT skeeve DOT com

J Booth

unread,
May 21, 2021, 1:04:00 AM5/21/21
to
> FYI, that's a Unix PC / 7300 that you have, not a 3B1.

Yep, yep! I often use the term interchangeably but you're right -- 3B1 is the humped machine. I much prefer the look of the original 7300 to the 3B1 hump. Though can't argue with the extra storage!
Reply all
Reply to author
Forward
0 new messages