[Coco] [coco] Coco CNC

George Ramsower georgeramsower at gmail.com
Wed Feb 13 20:41:39 EST 2008

From: "Gene Heskett"
> Yeah, I've been meaning to ask how the coco is actually interfaced to the
> motor drivers, can you clarify that George?

  Years ago, I built an interface board that connects to a Y cable. On that 
board is a 1 of 16 decoder addressed to the last bit.
 Also there are four 8 bit output latches and four input buffers. This uses 
a total of eight address spaces starting at FF60.
 FF60-FF63 are the output latches. FF64-FF67 are the inputs.
 Those are wired to DB-9 connectors. Those outputs are connected to an 
external box that has a 24V power supply and four ea. four darlington 
transistor arrays that step up the 5V signal from the coco and provides the 
current for the steppers.
 In that outside box is also a provistion for one input array to one of the 
input buffers on the coco. Right now, I'm only using three bits for  the 
three home switches  on the XYZ axis'.

 It's really quite simple.

 FF60 is the X axis. It uses only four of the eight bits and so on..
 Originally I put two steppers on one latch, but the math slowed the poor 
coco down. Since I only need four axis, one per port made more sense and I 
switched to that ideal.
 I built this coco for the purpose of home security and just playing with. 
But when I decided to make a CNC machine, it was already set up (hardware 
wise) to do this. I didn't have to modify the coco at all. Now, when I want 
my security thing, I just unplug the CNC machine and plug in the security 
stuff, pop in another 3.5" floppy, reboot and viola! A computer can be 
whatever we wish.

 What FUN!! I love my cocos!!

 This is almost as good as sex!!...... almost.
 Anyway, it's a danged site better than TV, now that the Writer's Guild is 
taking a vacation.
 Damned unions.
 Greed is why we are approaching a recession. I could go on and on, on that 
subject, but there's not enough room in my coco for all what I think on 


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