PDS slots in NuBus Macs

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doug-doug the mighty's picture
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PDS slots in NuBus Macs

Does anyone know if the PDS slots found in various NuBus Macs are the same? By this, I mean are the pinouts the same. What I am getting at here is taking a PDS card for a PowerMac 6100 or a Workgroup Server 9150/80 and transplanting it to a Quadra 950. At first blush, I see no reason why this will not work, but cannot find any good doc to add comfort to my thinking and I do not want to get a card ($) and plug it in just to find out (fzzt-snap-crackle-poof). Not that the target is a Quadra and the donor card is known compatible for the aforementioned machines.

--DDTM

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Hmm...

I'm pretty sure that it won't work. The PDS slot was usually dependant on the processor (030,040,601). Cards were made to work with a certain one and were unable to work with another. I don't know if it would fry the card, though.

Jon
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Tid bits of info: [url]http:/
doug-doug the mighty's picture
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let me get this straight...

According to eeun on his September 17, 2004 - 5:58pm (EST) posting, the PDS slot in the 6100 is the sam as the Q700, which is indeed the '040 PDS slot (directly implying that the Q950 PDS slot would work as well.

Using this logic (said logic being that a card known to be compatible with a 6100 PDS slot, which is a perfect match for a Q950 PDS slot) (and here I drop the other shoe), I could drop in a Crescendo/NuBus G3 (http://sonnettech.com/product/crescendo_nubus.html). After reading the thread (and thanks for that!), it sounds like this would work unless I have completely missed something.

The end result of this crazy logic is that my Q950 could become a G3 500MHz. Sound unreal, but from what I have read on thread (http://sonnettech.com/product/crescendo_nubus.html) and at Sonnet, this looks compatible, despite Sonnet saying that they doubt it and do not support it (a typical response for these type of questions).

Can someone please confirm my thinking.

--DDTM

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I'd eat my iBook if

[qoute: "The end result of this crazy logic is that my Q950 could become a G3 500MHz"]
:o
I'd eat my iBook if that were true. Though, you would think it would be so limiting because of the ram and bus speed. You might be able to compensative by upping the board speed a-bit. Boy, that sure would be a screeeaaaming Quadra. I wonder what the benchmarks would be after that were installed though....

Any body willing to sacrifice those parts to see if they work together??

doug-doug the mighty's picture
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yes.

If I can get my hands on the upgrade card for cheap, I will do it. I was thinking just after my last post that the bus speed and RAM may play a factor, but I am up to trying it out. If my Quadra dies, I can always use the case for holding USB drives for my iMac.

So we have a Quadra 950as a donor machine. Anyone got a (WORKING) Crescendo NuBus G3 (500MHz) they are willing to trade? I may be able to scare up a working eMate 300, or a PowerMac 8100, or an LC 580, or some UMAX scanners, or something.

Is your iBook a clamshell or a Ti? If it is the latter, it may leave you with a metal after-taste in your mouth. Acute

--DDTM

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Dunno 'bout this . . .

as yer trying to go in the opposite direction from the available adapter. The 6100-PDS-DOScard adapter plugs into the 6100 PDS slot and provides an '040 PDS slot. Yer talking about plugging a 6100-slot item into a Q950's '040 PDS slot . . . not exactly the same thing.

I like the out-of-the-box thinking here, but yer pretty far out of the box. You'll have to create the adapter from scratch, not an easy task. Then there's the totally unproven concept of using a nubus G3 card in a pre-PPC Mac. A pretty steep climb if you don't mind my saying so.

Read the devnotes for the relevant Macs, the slots are documented.

dan k

jt
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Re: Dunno 'bout this . . .

dankephoto wrote:
You'll have to create the adapter from scratch, not an easy task. Then there's the totally unproven concept of using a nubus G3 card in a pre-PPC Mac. A pretty steep climb if you don't mind my saying so.

Read the devnotes for the relevant Macs, the slots are documented.


Agreed on the steep climb part and the devnotes . . . (the 6100 is the only one with documentation on the PDS slot, because Apple shipped the 7100 and 8100 with HPV or AV cards in the slot, so the geniuses decided nobody needed to know the PDS spec for them :rolleyes: )

. . . however, the adapter might not be all THAT bad! IIRC, somebody looked farther than I did into the MCA connectors Apple used as the PDS interface on the NuBus PPC trio. He even posted WHICH MCA riser card might be the most promising for PDS playtime hackage. If you could nab one of those risers, you'd be down to gender changer hacking to mate up the two female 040 PDS connectors.

Driver software would be the thing I'd worry most about, the only PPC hack for a Quadra I've ever considered would be to look for a 603e upgrade card to hack. Were any of those ever made? Dunno, I've never researched it, but the drivers would already be available and with a G3 interfaced at the CPU pad level, it'd just look like a really fast 603e to the Quadra OS.

jt Wink

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Heh heh heh, oh yeah, drivers . . .

like that's non-trivial!

The only 603/e/ev Quadra upgrade of which I'm aware is the PB500 series PPC upgrades. How that helps I have no idea.

Hmmmm, ISTR folks trying to stick a G3 on a PB500 PPC upgrade card, a non-starter IIRC.

dan k

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pinouts for 950

I actually did find the pinouts for the Q900 on some Apple devnotes (http://developer.apple.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-68K_Desktop/Mac_Quadra_900.pdf). I now have in hand PDS pinouts for the Q900/950 (my machine) and the PowerMac 6100. I can see right away that they do not match up, being out of order is trivial if building an adapter 'cuz you can always move things around, but here, there are a few pins missing from the Q950 that may be critical to the Crescendo card.

Further though on the matter is required...

--DDTM

jt
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Can the Crescendo . . .

. . . they're EXPENSIVE for hacking, the (low end 233 MHz) G3 ZIF cards are MUCH more economical for experimental purposes and the interface is even wire-wrap friendly! I've found a preliminary info .pdf w/pinout for them somewhere too, thanks to some help here in another thread. IIRC, there was even info on interfacing somethingor other with 680X0 systems . . .

jt :ebc:

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Sounds good!

Can you dig that up? I have been going over the pinouts for the 6100 and the 950 seeing what lines up and what does not with the apparent futile >:( hope of trying to hack something if I can make things line up enough. The ZIF may be a better approach and I am willing to try. This can help make some fantasies I have about the Quadra a reality for me! Biggrin

--DDTM

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Re: Sounds good!

doug-doug the mighty wrote:
Can you dig that up? I have been going over the pinouts for the 6100 and the 950 seeing what lines up and what does not with the apparent futile >:( hope of trying to hack something if I can make things line up enough. The ZIF may be a better approach and I am willing to try. This can help make some fantasies I have about the Quadra a reality for me!

You know, you really should back up a few paces.

The PDS slot in those machines is essentially a slightly buffered backdoor to the CPU data and address bus. In other words, the signals available are about what you'd get if you yanked the CPU off the motherboard and tapped the signals between it and the rest of the computer. With that in mind, remember: the Quadra and the 6100/7100/8100 lines use *different* CPUs. (The Motorola 68040 and PowerPC 601, respectively.) Don't take the fact that a fairly simple adapter can make an 040-slot peripheral card work in a 601 slot (as is the case with the 6100 DOS cards) as any indication that CPU card can be swapped between the two busses. After all, the DOS card isn't required to override the onboard CPU.

(There is a substantial amount of logic included on those PDS CPU upgrades to do just that. It's not like they just drop the new CPU onto the bus lines and magic happens.)

No one *ever* sold a PDS upgrade card which worked in both 040 and 601-based machines. There are 040-slot 601 upgrade card for Quadras, and 604 and G3/G4-based cards for 601 slots. (I'm sure those "missing pins" the 040 slot are 601-specific signal lines which the upgrade card needs to "take over" for the onboard CPU.) Of course, the existance of PowerPC cards for Quadras means that it would be *technically possible* to do a higher-spec-then-601 card for those models, but you're not going to get it by wire-wrapping half-a**ed adapters together.

(JT, tell me you're not serious about trying to wire-wrap the pins of a ZIF CPU card...) ;^b

In theory, I suppose you could get a 601 upgrade card *and* a Sonnet Crescendo, desolder all the logic from them, and manufacture a new circuit board which uses the 040-601 logic for the bus interface, and then piles on the 601-750 bus logic from the Crescendo. (And to make JT happy, you can point that at a ZIF socket.) That or you could take the direct approach and design from scratch a new circuit which translates directly from 040 to 750, hopefully while retaining some level of compatibility with the existing 601 software enablers. If you *really* think that's within your abilities, have at it.

--Peace

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Other PDS cards?

Quote:
The 6100-PDS-DOScard adapter plugs into the 6100 PDS slot and provides an ‘040 PDS slot.

So are there any other Quadra-era PDS cards that would work/be useful in a 6100?

jt
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Re: Sounds good!

Eudimorphodon wrote:
JT, tell me you're not serious about trying to wire-wrap the pins of a ZIF CPU card... ;^b

NAH! I'd probably do a circuit board layout. Wink However, as far as a proof of concept prototype goes, I'd seriously consider the wire-wrapping option for a SEVERELY underclocked testbed system.

jt :ebc:

http://www.google.com/search?hl=en&ie=ISO-8859-1&q=MPCPCMEC.pdf&btnG=Google+Search

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