Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Cyberus on January 11, 2004, 09:14:16 PM
-
The 86-pin connector on the side of the A500 is essentially the same as the A2000 CPU fast slot, except that pin 9(not connected on A500 bus) is a 28MHz line and pin 20 is not connected. So, in short, how would I go about adapting the A500 bus to take an A2000 CPU card?
Regards
-
Since you've gotten that far, it shouldn't be a difficult task for you?
You need to change the card edge into a female connector (perhaps use two 86 pin connectors and a load of wire) and then you need to get the missing signals from the A500's motherboard. (check the schematics for those)
Try and keep the wires as short as you can.
Some cards might have problems - I'm willing to bet that the A2000 bus has some minor differences in comparison to the A500.
-
http://www.aminet.net/hard/hack/2000slot.lha (http://www.aminet.net/hard/hack/2000slot.lha) ?
I don't know if that's what you're after, but just in case you haven't come across it yet... :-)
-
Well, what I meant is, how do I go about getting the 28MHz to the connector? It's just a case of taking it off the clock line on the motherboard and soldering a wire to pin 9 of the female connector on the mobo?
Or more importantly, a better question would be:
Is, and why is, the clock signal needed by an accelerator sitting in the CPU fast slot? Surely the accelerator generates its own clock signal?
-
Don't know if this will help ...
But I had a Supra 28mhz accellerator for my
A500 and supposedly, with a card edge extension
it could be plugged into an A2000 fast slot and the
card would work in the A2000.
Going by that would indicate no modifications
are needed.
They sold this same accellerator for both A2k and
A500.
-
Reading this I wonder:
Will it work the other way, too?
I mean, could you use accelerators for the A2000 like the 2060 for example, on the A500 / A1000 ???
Have fun,
McTrinsic
-
Cyberus Wrote:
"Well, what I meant is, how do I go about getting the 28MHz to the connector? It's just a case of taking it off the clock line on the motherboard and soldering a wire to pin 9 of the female connector on the mobo?
Or more importantly, a better question would be:
Is, and why is, the clock signal needed by an accelerator sitting in the CPU fast slot? Surely the accelerator generates its own clock signal?"
---------------------------------------------
Ok well I'm no expert in this because it's been a long time since I looked at an A500 and I've never owned an A2K but basically the accelerator is going to be looking to obtain it's clock from the motherboard for timing purposes. Timing is everything when you start talking digital electronics, and that 28Mhz clock will no doubt ensure that things which are happening on the motherboard tie in with events on the accelerator. Without this synchronisation the accelerator is never going to work.
I have my reservations about this working but as I said I'm no expert when it comes to the A500 and A2K. But if it were possible, you'd think companies would have thought of it already - why make 2 production models of a card when you can make one to suit both? You'd think there must be a reason. Unless of course it was so they could put the two cards in a different price bracket ;)
Is there a 28Mhz clock signal available on the A500 mobo? If so you're going to want to take a tap of it, but be careful where you run the wire because you don't want any Interference generated in it. I don't think you can even look into buffering the clock signal, because the propogation delay involved would then put the clock signal out of sync with the mobo.
Good luck - and keep us informed
BrianH
-
Is there a 28Mhz clock signal available on the A500 mobo?
Yes! Look at the schematics near the Agnus, IIRC.
-
that_punk_guy wrote:
http://www.aminet.net/hard/hack/2000slot.lha (http://www.aminet.net/hard/hack/2000slot.lha) ?
I don't know if that's what you're after, but just in case you haven't come across it yet... :-)
That's for a Zorro II slot.
-
Cyberus wrote:
Well, what I meant is, how do I go about getting the 28MHz to the connector? It's just a case of taking it off the clock line on the motherboard and soldering a wire to pin 9 of the female connector on the mobo?
Or more importantly, a better question would be:
Is, and why is, the clock signal needed by an accelerator sitting in the CPU fast slot? Surely the accelerator generates its own clock signal?
Well, if you like, you can try it without the 28MHz signal, bu t otherwise you need to snipe it off the A500's mobo somewhere. Check the schematics. The Agnus has a 28MHz pin IIRC.
-
Jope wrote:
Cyberus wrote:
Well, what I meant is, how do I go about getting the 28MHz to the connector? It's just a case of taking it off the clock line on the motherboard and soldering a wire to pin 9 of the female connector on the mobo?
Or more importantly, a better question would be:
Is, and why is, the clock signal needed by an accelerator sitting in the CPU fast slot? Surely the accelerator generates its own clock signal?
Well, if you like, you can try it without the 28MHz signal, bu t otherwise you need to snipe it off the A500's mobo somewhere. Check the schematics. The Agnus has a 28MHz pin IIRC.
The A500 edge connector puts out a 7Mhz signal right? It's a long shot but one could include a clock multiplier to feed the 28Mhz pin on the adaptor? Maybe that wouldn't sync properly, I don't know :-?
-
The A500 edge connector puts out a 7Mhz signal right? It's a long shot but one could include a clock multiplier to feed the 28Mhz pin on the adaptor? Maybe that wouldn't sync properly, I don't know
Yes, why not.. I guess that's what the Supra Turbo 28 did..
Then again, since this is a homebrew mod requiring a ton of wire anyway, one more can't hurt so it can be tapped off the Amiga's internal 28MHz clock. :-)
-
Jope wrote:
The A500 edge connector puts out a 7Mhz signal right? It's a long shot but one could include a clock multiplier to feed the 28Mhz pin on the adaptor? Maybe that wouldn't sync properly, I don't know
Yes, why not.. I guess that's what the Supra Turbo 28 did..
Then again, since this is a homebrew mod requiring a ton of wire anyway, one more can't hurt so it can be tapped off the Amiga's internal 28MHz clock. :-)
I wouldn't want to have a motherobard patch and not as a nastly long wire from poor agnus... a better solution would be to multiply the signal from Pin7 and connect it to Pin20, that way he could use his adaptor on any A500 :-)
-Edit- This should help A500 Theory of Operation (http://www.matthewdesantis.com/a500sm.html+block+diagram+a500&hl=en&ie=UTF-8)
-
Jope wrote:
Cyberus wrote:
Well, what I meant is, how do I go about getting the 28MHz to the connector? It's just a case of taking it off the clock line on the motherboard and soldering a wire to pin 9 of the female connector on the mobo?
Or more importantly, a better question would be:
Is, and why is, the clock signal needed by an accelerator sitting in the CPU fast slot? Surely the accelerator generates its own clock signal?
Well, if you like, you can try it without the 28MHz signal, bu t otherwise you need to snipe it off the A500's mobo somewhere. Check the schematics. The Agnus has a 28MHz pin IIRC.
Yep, pin 34 of the Agnus is the 28MHz
-
I found something similar in a mag called "A1000 Journal", made by and for a few german A1000 freaks during 1991 to 1993/94.
One of the articles deals with a busboard extender or something similar to put an A2630 in it, and it worked - on a A500, that is.
Its all in German, though.
The article is here:
http://rammstein.dfmk.hu/~joerg/1000er-Magazin/1000er-Disks/9305/Hardware/+a2630-A1000.txt
Have fun,
McTrinsic
-
If you aer still interested, have a look at
this:
http://amiga.resource.cx/exp/search.pl?product=trumpcard500&company=
and especially these:
http://amiga.resource.cx/exp/search.pl?product=dma&company=rex&amiga=&intf=&mid=&base=dec&pid=
http://www.amiga-hardware.com/micro500busboard.html
Exactly what you are after!
Have fun,
McTrinsic
-
Thanks! I had seen the adapter for the trumpcard before, but the DMA adapter would be perfect!
I will have to keep a look out for one. Things like this tend to appear on German ebay more than on UK ebay.
-
In fact, has anyone ever seen one? I mean, is it actually worth me looking :-?
-
Havent really seen one.
Not as an auction within the last year on ebay.
Only place I found about it was an amiga.resource.cx
Sorry.
My experience is, however, that such things DO turn out on ebay, sooner or later. Some later, though, and most of the time with incredible prices...
Have fun,
McTrinsic
-
Well, there is also the AmigaNet 500 (http://amiga.resource.cx/photos/photo.pl?id=amiganet500) connector, which was used to connect the Zorro II AmigaNet (http://amiga.resource.cx/exp/search.pl?product=amiganet2000) Ethernet interface, but I don't know if it will work with an A2000 CPU card :-?