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also, re LC-PDS devices: it wouldn't at all surprise me if the graphics and video capture devices are the kinds of things that don't work on the 6200 (or perhaps the 575/580/630) because of the lack of actual "processor direct" access.

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On 4/18/2019 at 12:48 PM, Cory5412 said:

The 6200/6300 all did. I still haven't had a chance to look at the 6300 developer note to see what Apple said there. As far as I know, Apple never published a revision to the 6200 note, so it's possible that the speeds of the 603 bus are different from the two models.


Notably, the only things on the 603 bus are the CPU itself, the Calpella, and the ROM/Cache, so none of the existing chips from the 030/040 platforms involved in the 630/6200/6300 platform need to run at "very" high speed. Those buses (the '040 bus connecting Calpella to PrimeTime I/II/III, F108, and Valkryie, and the '030 PDS and i/o stuff coming out of Primetime II run at) run at their own speeds. The developer note for the 6200 does also state the speed of the 603 bus (it says it's the same speed as the CPU frequency) and the i/o bus coming out of PrimeTime II, but it doesn't specify the frequencies of the 040 data/address buses.


It's possible that the 040 bus in this machine runs at 37.5MHz, but the 603 bus is disconnected, logically and physically, from the 040 bus and doesn't need to run at the same speed. As the Taylor Design article says, basically  Calpella/F108 is the northbridge and PrimeTime is the southbridge.

You mean this, copied straight from the 5200/6200 Dev Note:


The internal bus structure consists of three internal buses; the 64-bit wide 603 data bus, the 32-bit wde 68040 bus, and the 32-bit wide I/O bus. The 603 bus is connected directly to the main processor and runs at the same clock rate. An external 256 KB second-level cache and 4 MB of ROM attach directly to the 603 data bus and help to optomize system performance. 

Yes it says the 68040 bus is 32 bits "wde", and that L2 cache is attached to the 603 bus and helps to "optomize" system performance. Typos and omissions aren't exactly foreign to these Dev Notes. Note my previous observation that there are exactly zero references to the system bus speed, only to processor internal clock and the 16MHz of the CS/LC PDS slots. It doesn't mention system RAM speed either.


Did you read previously where I noted that there existed ZERO 603 processors that could run at 1:1 processor:board speed exceeding 66MHz? I linked the 603 UM. It's not that many pages. That alone should be enough of a clue that anything physically external to the 75MHz processor on a 6200 is running at a lower rate, specifically no greater than half of that (which is 37.5, if you're curious).


Or maybe the fact that absolutely no Apple support chips produced in 1995 ran faster than about 50MHz, including Capella? Even if it did, there's the fact that neither the L2 chips or Capella changed with the increase to 100 or 120MHz 603e models. If the faster 603e chips ran their external L2 caches at 100 or 120MHz, why did they use exactly the same L2 cache modules from the 75MHz models? Were they somehow upward compatible with a >25% increase? And why did the faster 603e require a heatsink while Capella, now supposedly also running at 100 or 120MHz, didn't? It's because everything outside of the processor on the new models ran at 40MHz while the 603e ran at a multiple of that (2.5 or 3x) internally. Again, according to the documents from Motorola, there were exactly zero 603 or 603e chips that could exceed a 66MHz bus.


Go boot a 52/62/53/63xx, run TattleTech/Newer Gauge or Clockometer/Speedometer/Metronome/whatever and tell me what speed it has the system bus and L2 caches. I guarantee it's 37.5 on the 75MHz models and 40 on the 100/120MHz models.


Anyway going through my cache of Dev Notes, I don't have one for the 6300, only the 5260 which is basically the same as far as the board is concerned: it runs the 100MHz 603e instead of the 75MHz 603. I don't have any Dev Notes for any machines with the 120MHz 603e or the latest variants with soldered ROM and vacant L2 cache slots. These things don't have the greatest documentation.


I'll concede the CS/LC PDS thing as being a rare perfect storm, if it happens at all; I've never tried it because I have few non-Ethernet LC PDS cards. However, as you noted with the CS Ethernet and IIe card where "Apple says it won't work", I'll assume this is because the CS and LC PDS slot share the same 030 bus and only one can be active at a time. So basically choose one and forget the other (excepting CS modems, which are basically serial pass-through devices not on the 030 bus). Not that there were a ton of options outside of networking anyway.

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25 minutes ago, Franklinstein said:

I'll assume this is because the CS and LC PDS slot share the same 030 bus and only one can be active at a time

Your guess here is wrong. The stated/accepted reason is because CS devices want/use 32-bit addressing mode.


In reality, it might actually work, who knows. There's been some work, if I remember correctly, on running the IIe card in the 580/630, and that same work might allow it to work in a 575 with an ethernet Comm Slot device. (if it's been successful, I dont' know the status on that.)


However, CS ethernet should work with other PDS devices. that was never a documented as a limitation of any of these systems.


29 minutes ago, Franklinstein said:

Or maybe the fact

Okay, conceded. We've gotten a little beyond the point of my statement which is that the Taylor Design article, while having a technical error or two (based on Apple's own writing) is the most correct available after-the-fact assessment of those machines.


I have a 6220/75 at home, as I've said, it's "fine" with PPC native code -- I've run 7.6.1 and 9.1 with a couple different apps, which TBH almost everything I happen to use is, I'll pull out some older 68k versions of things and poke around with it at that point.


The other thing to remember here is that, again, a 6200 with a monitor, keyboard, mouse, a raftload of software, and usually a modem or a printer cost 1/5 of what a 9500 with a mouse and a text editor cost. It cost around half of what a thusly equipped 7500 cost, and if you added a keyboard and monitor to a 7200, you were also at about two 6200s.


It was an insanely good deal, for which there was a compromise if you bought, borrowed, or already had certain kinds of older software.

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