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Apple Macintosh II Bus Master NUBUS card?

Johnnya101

Johnnya101

Well-known member
Have the chance to buy an Apple Macintosh II Bus Master card. Can't find any info online about it. Model number 077-8264-C.

What does one of these do and is there anything it is actually useful for?
 
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cheesestraws

Well-known member
It enables NuBus block transfers in the absence of any other card that can act as a NuBus bus master. This allows for faster transfer of big chunks of data over the bus.

A practical use: some video cards had bus master circuitry built in, I believe the 8•24GC did (?). Some could act as slaves in the presence of a bus master, and those cards can be made to work faster by having a bus master on the same bus, either as part of another card or as a dedicated card, because with a bus master present, you don't have to write individual words to the card but you can write whole blocks of data at once. This is the dedicated card that provides the bus master function.

I'm not sure if it ever had any other practical use beyond "make some specific video cards go faster".
 
Johnnya101

Johnnya101

Well-known member
That makes sense, thanks for the explanation. So pretty much during the time of the Mac II and maybe early IIx before the high end video cards, this might have came in handy, but if you already have a pretty maxed out system it won't do too much.
 
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cheesestraws

Well-known member
I think you're going to have to ask someone who has a better grasp on the history of Mac NuBus that question :) . But I would personally assume that unless you have specific video cards (the 4•8 and 8•24 non-GC, as far as I know), it's probably not going to do very much. It may not do very much with those cards, either. Never tried it.

In short: assume it's a curiosity, and if you're prepared to buy it on those terns, you won't be disappointed. Practical benefits may be somewhat limited.
 
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