[Coco] RS232 Pak needed

[Gene Heskett]

On Friday 20 September 2013 07:39:45 Steve Bjork did opine:

> Picaxe are great for a quick and dirty test or small production of
> something.  But making a project with orders of 50 or more, I would use
> a pic or some other micro-controller with a lower cost than the Picaxe's
> $3.50.  (more like $0.75 each)
> 
> My first step is take a look at what you are trying to interface into
> the CoCo.  If we are looking at just older RS-232 device then making a
> replacement for the old RS-232 Pak is the direction we should go.  The
> cost of goods to build this type of board would run under $7.50.   The
> "hard" part of doing this project is writing the code to make the Pic
> chip think that its a 6551.  One option that we could add would be a
> large I/O buffer with full hardware handshaking.  That could speed up
> the I/O.
> 
> Steve

By 10x or so easily.  The current speed limit, using rzsz in nitros9, 
running on a 6309 is just about 625 cps. That is because the hardware flow 
controls in our current sacia based driver do not work. That guarantees 
good data, but a better protocol thats 10x faster because the hardware is 
better shouldn't be that hard to write. So the next question is to the list 
in general.

Assuming we do a 2 port version, and we could offer it for $60 by the time 
we get gold flashed boards, find out who made the cases Roger used, get 
some of those & modify that one for a pair of db9's, how many of you folks 
would buy it in the next year?

> 
> On 9/19/2013 11:21 PM, Gene Heskett wrote:
> > On Friday 20 September 2013 01:26:01 Steve Bjork did opine:
> > 
> > I am with you 100% Steve.  There is so darned much breakage in the
> > 6551 that we have tried to write code around for 30 years now,
> > without anyone doing anything to rectify the fact that it has more
> > bugs than a 10 day old carcass alongside the road.  That chip should
> > have been binned the instant a better one came along.  IMO the 16550
> > is not it as it ties up 16 IO addresses to properly handle it, so
> > thats a no go from the gitgo
> > 
> > With the pikaxe running from its own teeny little os in flash, all
> > we'll need to see are the 4 data & configuration port registers so it
> > looks most like the 6551 but actually has working flow controls. 
> > With a 2nd, 4 address wide port into its flashrom, even that could be
> > updated by the coco.
> > 
> > But I'd put a flea clip onboard write disable on that in case the coco
> > did a confetti screen too.
> > 
> > If you can send me the eagle files to build this serial port function,
> > preferably 2 or 3 up on one card, while staying inside the 4 address
> > limit for most coco i/o per instance per port, I will make the first
> > 2 cards on my milling machine.  If it works, the eagle files goto
> > somebody in Hong Kong for enough copy's to fill the needs at 1/8 the
> > cost for me to actually produce them in gty's.
> > 
> > Two gotchas for those 1st cards. (1 for you, 1 for me to be used as
> > test mules)
> > 
> > I cannot do plated through holes, so tsop packages would at least
> > solve that dip chip problem.  Any other thru via's needed, a bit of
> > wire will make these breadboard, proof of concept cards work.  If
> > someone can do the eagle files, I can do the rest, ready for part
> > soldering. I have done simple stuff (like the spindle encoder in my
> > cnc lathe) in eagle but a younger mind than my rusty wet ram will
> > probably do it faster for the more complex layouts.  It will be 79
> > the next time the date string says the 4th of the month. Stuff like
> > this "keeps me out of the bars". :-)
> > 
> > Forget the DB25 connectors, the 7 wire protocol thru a db9 connector
> > has been the default method for 20 years now, and saves acres of
> > board space.
> > 
> > As evidenced on this list, there IS a market for rs-232 port
> > cartridges. But one per "pack" is never enough.  If the 2nd one isn't
> > going to be used as a serial mouse port, which fixes the spastic
> > mouse with one that puts the click exactly where the pointer is, then
> > it could be made into a midi port, so the baud rate register should
> > include 31250.  I have done both at various times, currently using
> > the 2nd port for a mouse, a full 3 button mouse.
> > 
> > What say you, Steve?
> > 
> > Cheers, Gene
> 
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Cheers, Gene
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