[Coco] Orchestra 90/cc to Stereo Composer Conversion http://6809assemblylanguage.fortunecity.com/ORCH90CC-2-STEREOCOMPOSER.

[coco at yourdvd.net]

The TSC is used to tristate the buffer removing a14' from the address
bus. In the CoCo, the TSC is always tied high and isn't used. In my
Robotics Control Computer, I have designed it such that the Address Bus
is tri-stated anytime the E clock is low, which is why I have this
circuit going tri-state with the TSC line. I had eventually planned to
duplicate the 6847, giving it access to the address bus during E-low,
which is why I designed this circuit this way. The duplication of the
6847 is quite a ways off though. Lot's of timing issues in my design.
In a bit I will update the zip file to include the decoding for the
$FFC0 to $FFDF S.A.M. switches. My original goal was to design a fully
functioning coco clone, but I found it easier to design the SB-RCC
without video and S.A.M. wasn't necessary because of static RAM usage.
The zip file will eventually contain all of the circuitry that I have
developed over the past year in hopes that some of it may be useful to
those attempting to clone the CoCo. I am going to attempt to go to work
tonight, they would have done the surgery today even though they
couldn't verify the insurance, but I didn't wanna get stuck with a bill
I couldn't afford. Anyway, I am sitting here transcribing more circuitry
into schematics to update the zip file. The mmu I devised uses register
file I.C.'s (I was originally going to use static RAM for the mmu, but
I can't remember why I changed my mind.) - robert

> -------- Original Message --------
> Subject: Re: [Coco] Orchestra 90/cc to Stereo Composer Conversion
> http://6809assemblylanguage.fortunecity.com/ORCH90CC-2-STEREOCOMPOSER.
> From: jdaggett at gate.net
> Date: Mon, May 07, 2007 5:24 pm
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> 
> Interesting circuit. I have one question. The TSC line on the
> Translator circuit, Is 
> that from the TSC Input to the MC6809E?  If so it shou ld do nothing
> as the TSC 
> is an inout to the MC6809E and not an output.
> 
> james
> 
> On 7 May 2007 at 16:41, coco at yourdvd.net wrote:
> 
> > $FFF0-$FFFF TO $BFF0-$BFFF TRANSLATOR.pdf
> > This circuit is from a project I have been working on for over a year.
> > It is a single-board Robotics Control Computer (SB-RCC) Designed to
> > run OS-9 Level I and Nitros-9 Level I with minimal fuss. To that end,
> > the SB-RCC duplicates some of the weirdness of the MC6883/74LS783
> > S.A.M. chip. This particular circuit is designed to translate any
> > address in the range of $FFF0-$FFFF appearing on the CPU's address bus
> > (or is that buss) into $BFF0-$BFFF. Note: The S.A.M. only translates
> > addresses from $FFF2-$FFFF, but since $FFF0-$FFF1 is a "reserved"
> > interrupt, I figured No Harm, No Foul, and besides, it made design
> > much simpler. Other circuits from this design include some to
> > duplicate the write only switches of the S.A.M. and an MMU that
> > functions like the one in the CoCo 3 (I want it to eventually do Level
> > II and the MMU isn't that difficult to duplicate) - As soon as I find
> > where I placed those schematics (they're around here somewhere), I'll
> > add them to the zip file. There is also an infrared eye circuit and a
> > 40Khz sonar circuit to allow a robot to navigate. OS-9 is perfect for
> > this sort of thing!
> 
> 
> 
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