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#1 2015-10-23 20:06:26

MJ313
Member
Registered: 2014-09-23
Posts: 493

LC accelerator question

Is there a way to cajole an LC PDS accelerator into working in an SE/30?  Please pardon my naivete in these matters.

smile

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#2 2015-10-23 21:03:52

Eudimorphodon
Member
Registered: 2014-09-02
Posts: 522

Re: LC accelerator question

I think the short answer is "no" because the LC PDS slot is rather drastically different from the SE/30's, but perhaps someone can expand further.


Flap Different.

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#3 2015-10-23 21:19:33

MJ313
Member
Registered: 2014-09-23
Posts: 493

Re: LC accelerator question

Thank you sir, I figured it was probably a quick No.

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#4 2015-10-23 23:34:09

bbraun
Member
Registered: 2014-05-29
Posts: 1,064
Website

Re: LC accelerator question

I have the vaguest of understanding of the processor specific signals, so anyone who has more details, feel free to enlighten me.  It seems like doing such an adapter would require removal of a lot of circuitry from the accelerator board or some additional circuitry to "stub out" host processor functions.
The LC PDS was originally designed for the 020, which was relatively simplistic.  It was basically an SE's 68000 PDS with the addition of the function code lines and some other things to support FPU, MMU, etc.
The 030PDS on the other hand, has all the stuff of the 030 with cache controls and whatnot.  It was possible to add an external cache, like with the IIci's cache card.
When accelerators were made for the LC PDS with 030 and 040 processors, they had to handle all that on the accelerator its self, and "dumb down" the accelerator's processor interface when going over the LC PDS.
So it seems like those extra signals on the 030PDS would need to go somewhere.  Either remove some of the accelerator card's internal handling of those signals and break them out to the 030PDS interface, or you'd have to add additional components to fake out the host's bus, like maybe holding cache inhibit forever.
There's also more interrupts on the 030PDS than the LC PDS, which would need to go to the processor somehow, or some peripherals might not work.  I'm not sure how big a deal that'd be.
There's also some differences in how the memory controller responds between the two systems, with the dynamic bus sizing abilities.
And it looks like the address lines are different between the two, which probably explains why machines with LC PDS never had much expansion, it has limited address lines.

It certainly seems like a non-trivial exercise to me.

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#5 2015-10-24 00:52:14

MJ313
Member
Registered: 2014-09-23
Posts: 493

Re: LC accelerator question

My curiousity was piqued by this:

http://www.ebay.com/itm/141785451120?_t … EBIDX%3AIT

It seems to be an adapter for both an LC and LCII. An LCII already has a 030 in it... so my mind kind of just thought, well, seems close enough... why wouldn't work? lol.  Well, seems like there are plenty of good reasons why it would not work!

Last edited by MJ313 (2015-10-24 12:14:08)

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#6 2015-10-24 03:41:01

jt
Member
From: Bermuda Triangle, NC USA
Registered: 2014-05-21
Posts: 1,376

Re: LC accelerator question

Piqued! wink  Mine too, that looks way cool, is that crazy edge connector a PDS Passthru,  memory or Video card interface?

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#7 2015-10-24 12:15:26

MJ313
Member
Registered: 2014-09-23
Posts: 493

Re: LC accelerator question

lol, fixed! thank you no-timeout-edit rule tongue

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