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Apple Macintosh II Bus Master NUBUS card?

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?
 

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

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.
 

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.
 

MrFahrenheit

Well-known member
Is it this one?


What is that busmaster card used for ?

It’s “bundled” in a lot on eBay right now:

 
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Phipli

Well-known member
What is that busmaster card used for ?

It’s “bundled” in a lot on eBay right now:

I believe it takes some load off the cpu, freeing it up to do other things. It would be interesting to know what application they were used in.

Radius rocket supports bus mastering. Uses it to directly control other cards and provide them within the rockets OS instance as if they were plugged directly into it. Also to accelerate non-accelerated radius graphics cards.

The 8•24 GC can accelerate the vanilla 4•8 and 8•24 cards in the same machine by block transferring directly into their framebuffers as cheesestraws was saying.
 

cheesestraws

Well-known member
What is that busmaster card used for ?

I explained it upthread :). It allows NuBus cards which support it to do block transfers, which allow them to access memory or other devices far more efficiently. Later on, cards that could take advantage of this tended to have bus mastering circuitry built in, so on a Mac, this card is mostly only useful for speeding up a handful of very specific Apple video cards (the 4•8 and 8•24 non-GC, as far as I know). Beyond that, it's probably just a curiosity.

It's bundled a lot because it's obscure and, as far as I can see, basically useless :) .
 

MrFahrenheit

Well-known member
I explained it upthread :). It allows NuBus cards which support it to do block transfers, which allow them to access memory or other devices far more efficiently. Later on, cards that could take advantage of this tended to have bus mastering circuitry built in, so on a Mac, this card is mostly only useful for speeding up a handful of very specific Apple video cards (the 4•8 and 8•24 non-GC, as far as I know). Beyond that, it's probably just a curiosity.

It's bundled a lot because it's obscure and, as far as I can see, basically useless :) .
Ah ok. Sorry I missed that above.

I see that someone bought one of these same cards on eBay for $145 recently. So I guess there are people who are looking for this obscure card. Not sure what I’ll do with it. I don’t think I have either of those two video cards.

Will this card work in a IIfx and is there a better video card solution than this an an 8*24 card? I don’t remember what’s in one of my IIfx machines, but I think the second IIfx I have used a Palet card (or emachines, can’t remember). It was a strange one (to me).

I guess I should probably setup a IIfx that is an ultimate machine at some point.
 

Phipli

Well-known member
Ah ok. Sorry I missed that above.

I see that someone bought one of these same cards on eBay for $145 recently. So I guess there are people who are looking for this obscure card. Not sure what I’ll do with it. I don’t think I have either of those two video cards.

Will this card work in a IIfx and is there a better video card solution than this an an 8*24 card? I don’t remember what’s in one of my IIfx machines, but I think the second IIfx I have used a Palet card (or emachines, can’t remember). It was a strange one (to me).

I guess I should probably setup a IIfx that is an ultimate machine at some point.
This and a vanilla 8•24 aren't going to be spectacular. The 8•24 GC has QuickDraw acceleration and masters other vanilla 8•24 cards, this card doesn't have quickdraw acceleration.

I suspect it would be used for very specific applications like data capture in a test lab or video capture rigs. I suspect you'd be using it where you wanted to move data quickly between two cards, rather than as a graphics card accelerator. But... I've never seen one in the wild, so I don't know what people used them for.

Take care with completed listings, eBay lie sometimes - I've had offers accepted and seen the completed listing show the non-offer price, or there be no completed listing for my item if you search the next day. There are also certain... sellers that blatantly manipulate completed listings, such as Mr. Spotty Tablecloth.
 

cheesestraws

Well-known member
So I guess there are people who are looking for this obscure card.

I suspect some people will want it just because it's obscure and a bit unusual, though $145 seems a bit OTT... It's also a thing that is very specific to a time period, when that circuitry wasn't cost-effective to embed on cards that could benefit from it. So I'd imagine someone with a focus on collecting NuBus cards might be extremely hot on it if they were trying to find representative builds from different time periods.

@Phipli's idea that some kind of high bandwidth data capture would find this useful is also true—I don't know of anything, but that doesn't mean it doesn't exist, the list of things I don't know about is extremely extensive :)
 

MrFahrenheit

Well-known member
This and a vanilla 8•24 aren't going to be spectacular. The 8•24 GC has QuickDraw acceleration and masters other vanilla 8•24 cards, this card doesn't have quickdraw acceleration.

I suspect it would be used for very specific applications like data capture in a test lab or video capture rigs. I suspect you'd be using it where you wanted to move data quickly between two cards, rather than as a graphics card accelerator. But... I've never seen one in the wild, so I don't know what people used them for.

Take care with completed listings, eBay lie sometimes - I've had offers accepted and seen the completed listing show the non-offer price, or there be no completed listing for my item if you search the next day. There are also certain... sellers that blatantly manipulate completed listings, such as Mr. Spotty Tablecloth.

Ah yes, Mr. Polkadots. I think we may have figured him out. eBay has a workaround that allows you to manipulate their sold history. If you list a $3000 Mac prototype as a buy it now item, after it sells you can change the title, description, photos, and price to something that is far cheaper, and it still shows the sold history. Meaning, you can manipulate the sold amount on a listing by constantly changing it around.

Not saying this is what Polkadots does for sure (it's purely speculation), but here's an example listing where it could be manipulated in this way:


Untitled-example.png

If you look, January 27, 2020, one is reported as selling for $36.99. Now, I've seen a lot of deals on things, but I can guarantee you that nobody who sells quantities of Mac stuff has sold a Mystic Color Classic for $36.99 in 2020.
 

MrFahrenheit

Well-known member
I suspect some people will want it just because it's obscure and a bit unusual, though $145 seems a bit OTT... It's also a thing that is very specific to a time period, when that circuitry wasn't cost-effective to embed on cards that could benefit from it. So I'd imagine someone with a focus on collecting NuBus cards might be extremely hot on it if they were trying to find representative builds from different time periods.

@Phipli's idea that some kind of high bandwidth data capture would find this useful is also true—I don't know of anything, but that doesn't mean it doesn't exist, the list of things I don't know about is extremely extensive :)

I do have an AST NuBUS x86 card in one of my IIfx machines. Actually, I think it may be two cards (or two slots). I wonder if this bus master card would help it out... the possibilities are endless I suppose.
 

Phipli

Well-known member
Ah yes, Mr. Polkadots. I think we may have figured him out. eBay has a workaround that allows you to manipulate their sold history. If you list a $3000 Mac prototype as a buy it now item, after it sells you can change the title, description, photos, and price to something that is far cheaper, and it still shows the sold history. Meaning, you can manipulate the sold amount on a listing by constantly changing it around.

Not saying this is what Polkadots does for sure (it's purely speculation), but here's an example listing where it could be manipulated in this way:


View attachment 45475

If you look, January 27, 2020, one is reported as selling for $36.99. Now, I've seen a lot of deals on things, but I can guarantee you that nobody who sells quantities of Mac stuff has sold a Mystic Color Classic for $36.99 in 2020.
I assumed he sold to himself and then canceled it. Refunded but the sale remains.

$36 is weird though.
 

Phipli

Well-known member
@cheesestraws @MrFahrenheit @Johnnya101

Well, this might answer it. Seems they are part of an Apple diagnostics kit :)

Likely not much use for anything else. They might just take over the computer and run diagnostics, even if the main computer is unable to boot or something.
 

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MrFahrenheit

Well-known member
@cheesestraws @MrFahrenheit @Johnnya101

Well, this might answer it. Seems they are part of an Apple diagnostics kit :)

Likely not much use for anything else. They might just take over the computer and run diagnostics, even if the main computer is unable to boot or something.
Interesting! Thanks for the file!

I just purchased that kit, not really knowing what all was involved. It was unused, still sealed and seller opened just to document what was inside. I should have it in a couple of weeks but will be away.

I had wondered why that card was part of the kit. Now I know. Thanks!!
 

cheesestraws

Well-known member
That may be a slight red herring: note tha Bus Mastering is a specific NuBus thing, and I suspect it's there so that you can fully test the NuBus under diagnostic conditions. It almost certainly does *not* permit running the tests themselves, especially since it's marked as 'optional' on that packing list, and there's no reason why Bus Mastering would make that work better.

That would explain where they came from, though, and why there are so many out there.
 

MrFahrenheit

Well-known member
That may be a slight red herring: note tha Bus Mastering is a specific NuBus thing, and I suspect it's there so that you can fully test the NuBus under diagnostic conditions. It almost certainly does *not* permit running the tests themselves, especially since it's marked as 'optional' on that packing list, and there's no reason why Bus Mastering would make that work better.

That would explain where they came from, though, and why there are so many out there.

So, basically, what you're saying is that Apple likely included the Bus Master card with the diagnostics kit, because using a software tool, one could verify the NuBUS works on a Mac by the diagnostics accessing and probing the Bus Master card? That's my take-away from that.
 

Phipli

Well-known member
So, basically, what you're saying is that Apple likely included the Bus Master card with the diagnostics kit, because using a software tool, one could verify the NuBUS works on a Mac by the diagnostics accessing and probing the Bus Master card? That's my take-away from that.

Worth noting it tells you to put an Apple video card in a specific slot, so I suspect it might help display something on the computer undergoing test.

I'm just guessing from a poor description though. Can't wait to see you run through what it can do once you get the kit :)
 
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