[Color Computer] [coco] software modem for OS-9

[Gene Heskett]

On Thursday 07 July 2005 21:05, George Ramsower wrote:
> I can't imagine why anyone would want to do this, but I'm curious
> if someone ever wrote a routine for OS-9 that will use the cassette
> port to communicate with a device using modem tones A.K.A. FSK...
> like is used to utilize the cassette in RSDOS.
> Perhaps in amateur radio land there was something to use on radios
> to transfer data, before the modem chips caught up with packet
> radio?
>
> My purpose is to use my TRS-80 Color Computer Plug-N-Power timer
> with OS-9. Since the timer uses FSK for data exchange with the
> coco, normal OS-9 drivers won't do this.

There is a reason they don't George.  The interrupt timing in os9 is 
such that software generated tones are not possible.  For 0s9, one 
must use a hardware tone generator that can carry on the tone even 
when the os is off checking for an incoming byte from a hardware 232 
card.

You can write stuff to bang the port ok, but what comes out is going 
to sound far differently than any continuous tone you've ever heard, 
very sputtery.  Ditto for receiveing any data thru the seriel or 
cassette ports at any usable speed above about 60 baud.

This is why, if you wanted to go online with os9 back in the days of 
delphi and running up your long distance bill, you absolutely had to 
have an rs232 pack or its equivalent.  Been there, done that, clear 
back on a old grey ghost coco with os9 level 1 version 1.00.01 (or 
was it 2.00?)  My LD bill was over $200 one month when I was 
accessing delphi with a 300 baud modem.  We've come a looong way baby 
since then!

> If there isn't a driver for this, perhaps someone has an old
> acoustical modem they might wish to part with. I can modify it for
> this application, using hardware to do the work which could be done
> in software, but I don't know how to program in assembly..

Humm, haveing been doing assembly on various cpu's clear back to the 
RCA 1802 in 1977 I guess was an education because that Cosmac Super 
Elf board didn't come with a higher level language.  The 1802 was 
easy once you understood its architecture, the Z80 was too, till you 
hit a string of Z80's that were crawling with bugs & zilog said I 
should go pound sand, "buy the newest ones, they work" when I called 
to complain that I had 2 of them that would only execute the $eb 
command properly on odd days of the month.  Compared to those 2, the 
6809 with its PCR abilities was a breath of fresh spring air.  If I 
had my druthers, I'd druther be doing assembly on a 4ghz, 64 bit wide 
version of the 6809.  Saddly that will only happen in my dreams.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
99.35% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com and AOL/TW attorneys please note, additions to the above
message by Gene Heskett are:
Copyright 2005 by Maurice Eugene Heskett, all rights reserved.


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