I know it isn't a PCI or AGP machine
I am customizing a 500 series for a future article??
It has NuBus-based archetecture, so yes.
No it's not. It uses a similar architecture to the nubus machines of the day, but it has no nubus controller in it. Back in those days, all of the i/o devices shared the 68K processor bus. None of them resided on nubus like modern machines do with PCI.
The Video subsystems were pseudoslot NuBus device implementations using exactly the same drivers and I/O memory mapping as actual NuBus devices and the "Slot E" PDS interface cards where available. The clearest example of NuBus archicture w/o NuBus controllers on b oard would be the Duos, which had the NuBus chipset tacked onto their bridged 030 bus. Come to think of it, the blackbirds used the same setup as the rest with a bridged 030 I/O architecture and the NuBus slot manager setup, IIRC.
edit: I think the "bridged 030 I/O bus" of the Quadra and NuBus PPC era probably WAS the NuBus equivalent of the PCI bus devices you mentioned in later Macs. Are there actual PCI bridge chipsets in moderin slotless PBs and iMacs or are there asynchronous split bus memory controller/bridge ASICs similar to PBX and a bridgeless PCI pseudoslot setup?
while I concede the lack of nubus controllers, I don't think saying something like 'PowerBooks 500 are not nubus Macs' really answers mobilepet's question.
It'd be easy to confound the issue with details, but with this sort of topic it's probably best to just keep it simple. mobilepet probably hasn't a clue about processor buses and 68030-compatible I/O buses. All they needed to know was that the PB500 belongs to a particular generation of Macs.
So really, the question isn't whether nubus is present but rather do PowerBooks 500 share the same basic architecture with contemporary nubus-containing Macs? The answer is of course yes, not "No it's not".
as always with questions about Apple's hardware products, one can get the answers straight from the horse's mouth:
Thanks so much for the help. I was looking for a shortcut, and you folks have given me it. I am actually trying to install some form of linux on the 520, which is "unsupported" on many lists. I wanted to know what architecture it was:
A m68k loader said "no, I won't work on your PPC upgrade.." (it has one)
Other distros say "works on ppc, but won't work on nubus.."
So, I have learned a bunch in the last 2 days. I am attacking another subject right now - from the MacOS side.
NetBSD/mac68k will run on the 5xx series of PowerBooks, if they still have the 68k daughtercard. I'm not aware of any Unix-like system that will run with the PPC upgrade. Maybe Minix, but that option isn't much use.
The nubus in the duo was provided by a nubus controller in the docking station. It passes the full 68K processor bus through the docking connector.
While the software erroneously reports the video chip as a virtual nubus device, I assure you, it most certainly is not. All the way up to the PPC nubus macs, all of the I/O devices, including the video chip sat directly on the CPU bus. (technically, on PPC I/O devices sit on the memory bus, but they certainly aren't on nubus).
I think the “bridged 030 I/O bus