Another STacy oddity...

DarkLord · Post by **DarkLord** » Sat Mar 16, 2013 8:08 pm

Thought I had this topic started already here, but maybe I had it included in my
"First PAK board attempt" message thread...so apologies if parts of it's there.

Anyway, some STacy models have a opening/slot on the side that covers an
connector place on the motherboard. There is not actual header there, just
the place for it. Here are some pics, you can see a case with and without
the opening:

PC110002.JPG

Now here is the motherboard itself:

Mystery port closeup.JPG

Look how similar it is to the VME standard:

vme-connector.jpg

It's also been suggested that it might be the same as or
similar to the Mega ST's internal bus port.

Now, here is a picture I found while googling:

STacy bus port.jpeg

At least 2 of my spare STacy cases have that opening/cover where this
port is, and 2 spare motherboards have the connections, but *none* of
my STacy's have the actual connector that's shown in this picture.

Does anyone have a STacy that actually has that header there?

ToasTuk · Post by **ToasTuk** » Sat Mar 16, 2013 10:22 pm

Sadly it appears to be a custom bus port like on the Mega ST & Falcon
, and not VME.
VME comes in two standards 96 pins (3x32) and 160 (5x32).
The port on the stacy is 72pins (3x24).
Interestingly the schematics detail the port and the silk screen shows it but when it comes to the case and connector these are missing, as on the machines in real life.

DarkLord · Post by **DarkLord** » Sat Mar 16, 2013 11:53 pm

Right, but what about that last picture? It has a connector facing outwards in it.

None of mine have that...

I also wonder if you soldered a header on to it, would all the signals be there?

rian_ata · Post by **rian_ata** » Sun Mar 17, 2013 12:46 am

No header on my Stacy2

stacy2_headers_left_side.jpg

DarkLord · Post by **DarkLord** » Sun Mar 17, 2013 1:08 am

Right, and all of mine (1 working, a couple of spares) are all the same way.

I know its a longshot, and most probably a pipedream, but if it was only as
simple as soldering on a header like the Mega ST's internal bus port and hooking
up a compatible video card!

ToasTuk · Post by **ToasTuk** » Sun Mar 17, 2013 9:00 am

I'm pretty sure the signals are there. A cable can be built to convert to megabus but most cards are built for VME. I do have an atari buffer card that I'm looking at to see if that is a viable VME extension and then a nova option (et4000) can be added not only on the Stacy but all STs.

ToasTuk · Post by **ToasTuk** » Sun Mar 17, 2013 12:24 pm

Ok just done a comparison between the stack expansion and the megabus.
The mega bus has 4 grounds and the stacy 12 so this means we have the same number of signals to deal with.
I have paired up all the signals like for like except the interrupt signals,
I believe a small piece of circuitry is required to make it 100% compatible if you need int7.
Megabus has nmi, int3 & int5
Stacy has eint7,eint5 & eint3

Ill keep looking at the stacy/mega schematics as I'm sure it will contain the answer we need.

ToasTuk · Post by **ToasTuk** » Sun Mar 17, 2013 4:37 pm

Ok it appears that the INT signals are supplied by the same circuitry on both machines. So all that is required is a cable to rewire to the megabus.
It gets better now, although the atari buffer card I have

has the B (middle) row of pins missing the nova project does not use them on the VME to ISA adaptor.
All we need to do now is reverse the pal logic on the board

And we are rolling.

DarkLord · Post by **DarkLord** » Sun Mar 17, 2013 7:36 pm

Wow, that sounds great.

Hmm weren't there a *few* video cards released for the Mega ST though? I think I've got
one, although it's not color - the Reflex board?

Thanks.

ToasTuk · Post by **ToasTuk** » Sun Mar 17, 2013 9:06 pm

Can't remember tbh, reflex sounds familiar and I'm interested to find out.
If you can find it, let me know if it has a megabus on it.
I can then type up the pinout conversion for you.

All you need in the megabus socket.

http://www.ebay.co.uk/itm/230882585042
This is the one I used as its local to me.

And plenty of wires in the absence of a pcb.

ToasTuk · Post by **ToasTuk** » Sun Mar 17, 2013 10:42 pm

Itchy fingers, started on the prototype board

TheNameOfTheGame · Post by **TheNameOfTheGame** » Sun Mar 17, 2013 10:51 pm

Haha you keep them fingers itchy

Good job.

DarkLord · Post by **DarkLord** » Mon Mar 18, 2013 2:50 am

ToasTuk wrote:Can't remember tbh, reflex sounds familiar and I'm interested to find out.
If you can find it, let me know if it has a megabus on it.
I can then type up the pinout conversion for you.

All you need in the megabus socket.

http://www.ebay.co.uk/itm/230882585042
This is the one I used as its local to me.

And plenty of wires in the absence of a pcb.

Okay, I went ahead and ordered 2 of those, thanks for the link.

Here is a picture of the reflex, I'll try to make some better ones and post them a bit later:

Reflex Mono.jpg

ToasTuk · Post by **ToasTuk** » Mon Mar 18, 2013 12:22 pm

Cool, I briefly retyped the pinout conversion last night and will post later after work

ToasTuk · Post by **ToasTuk** » Mon Mar 18, 2013 12:44 pm

Quality,
I briefly retyped the pinout conversion last night and will post later after work

ToasTuk · Post by **ToasTuk** » Mon Mar 18, 2013 1:27 pm

Sorry about the double post :/
My device to test it out arrived today

ImageUploadedByTapatalk1363612987.668789.jpg

wongck · Post by **wongck** » Tue Mar 19, 2013 12:05 pm

According to the Do_it files, only early Stacy has the mega bus connectors.
Later versions do not but the holes are still there.
Can be found here, search for word mega bus.

Mal7921 · Post by **Mal7921** » Tue Mar 19, 2013 1:40 pm

I remember taking that panel off mine ages ago, only to be disappointed to find the blanking plate. Never looked inside to see if there were any connectors or tracks for a connector to be honest, but if it is simply a rewired mega bus connector, then at least there could be some use made of it.

I guess Atari were thinking in the same way many laptop makers of the time were, connect the machine to a docking station to give additional expansion and/or functionality, but a bit pointless on the Stacy as it had all the ST ports already there. Possibly an early development hangover where test machines could be feathered to a mega ST for development or testing?

ToasTuk · Post by **ToasTuk** » Tue Mar 19, 2013 9:30 pm

Ok had Apple Mac issues (fingers crossed I've sorted that out

)

Here is the promised pinout conversion. I've tried to be as accurate as possible.
I have not assigned the grounds as they can be connected together.
Also note that like in the mega you need a power source as the bus only supplies signals.

www.atariuk.co.uk/index.php?nav=stacytomegabus

It's also interesting when comparing the megabus to the 68000 pin outs. With the exception of the vcc( these have been replaced with gnd), the pins between 33-64 being flipped and the IPL signals being changed with the EINT signals, its the same.

DarkLord · Post by **DarkLord** » Tue Mar 19, 2013 9:32 pm

wongck wrote:According to the Do_it files, only early Stacy has the mega bus connectors.
Later versions do not but the holes are still there.
Can be found here, search for word mega bus.

Thanks Wong, guess that explains that mystery.

DarkLord · Post by **DarkLord** » Tue Mar 19, 2013 9:35 pm

Here are a couple of shots of the Reflex board I have (wish it did more than
mono!).

Reflex video card (top).JPG

Reflex video card (bottom).JPG

Post by **joska** » Wed Dec 03, 2014 1:28 pm

Old thread, I know... DarkLord, do you have any drivers for that Reflex card? I have a driver disk but it seems to be outdated.

Btw your card is missing both pixelclocks.

DarkLord · Post by **DarkLord** » Wed Dec 03, 2014 11:32 pm

Hey Jo - lemme look through the box the Reflex card came in.

Hmm, missing pixelclocks? Hadn't noticed - but then, I've not
tried to use it anywhere. Are those easily obtainable? Thanks.

Post by **joska** » Thu Dec 04, 2014 9:44 am

See in the top left corner. There should be two oscillators there. In my Reflex the one on the right (U12) is 50MHz and the left one (U11) is 80MHz.

I think I saw atleast one oscillator in one picture in your PAK30 thread, so it has probably come loose during transport.

paul92706 · Post by **paul92706** » Thu Dec 04, 2014 4:24 pm

joska wrote:See in the top left corner. There should be two oscillators there. In my Reflex the one on the right (U12) is 50MHz and the left one (U11) is 80MHz.

I think I saw atleast one oscillator in one picture in your PAK30 thread, so it has probably come loose during transport.

I've ordered a few oscillators off ebay, for about $1 or $2, not hard to find and cheap on ebay!

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