Certainly the Mac OS (that's with a capital M) was not well-suited for handling the real-time demands of hardware: ADB, for example, requires quite a bit of polling, and the OS could not service the bus sufficiently often to make it effective for large-volume data transfer (condemning it to a largely HID-only capacity, though that's all it was really designed for). Daniel makes a very well-reasoned assertion that the computer's major problems were due to software instead of hardware design, which is at least partially true, but I think his objections are oversimplified.The only two entities which can be bus master are the CPU or either the PDS expansion card or communications card via the PrimeTime II IC "southbridge." More on that in the next point.ĭo note that the Q630 design does support bus mastering, but not from the F108. While this was no great sin when the Q630 was in production, it was verging on unacceptable even for a low-to-midrange system by the time the 6200 hit the market. More to the point, the F108's embedded IDE controller - because the 6200 actually uses an IDE hard drive - doesn't have DMA set up either: if the Q630 is any indication, the 6200 is also limited to PIO Mode 3. While the NCR controller that the F108 ASIC incorporates does support it, I don't see where this is hooked up. His article claims that both the SCSI bus and the serial ports have DMA, but I don't see this anywhere in the developer notes (and at least one source contradicts him).(See page 29 for the block diagram.) A 20-25% speed penalty (his numbers), however, is not trivial and I think he underestimates how this would have made the machines feel comparatively in practice even on native code. He's right that the L2 cache, which is on a 64-bit bus and clocked at the actual CPU speed, certainly does mitigate some of the problems with the Q630's 32-bit interface to memory, and 256K L2 in 1995 would have been a perfectly reasonable amount of cache.It's an understatement to observe that's not the most favourable environment for these chips, but it would have required much less development investment, to be sure. The Apple tech note says, "The Power Macintosh 52 computers are electrically similar to the Macintosh Quadra 630 and LC 630." It might be most accurate to say that these computers are Q630 systems with an on-board PowerPC upgrade.I'll just cite some of what I took as highlights and you can read the rest. That said, the effort is commendable even if I don't agree with everything he's written. He helpfully includes a local copy of Apple's tech notes on the series, though let's be fair here - Apple is not likely to say anything unbecoming in that document. If it is, here's his reasoning why the seething hate for the 6200 series should be revisited.ĭaniel does make some cogent points, cites references, and even tries to back them some of them up with benchmarks ( heh). The "Dtaylor372" listed in the edit log appears to be this guy, one "Daniel L. LowEndMac has a long list of its perceived faults.īut every unloved machine has its defenders, and I noticed that the Wikipedia entry on the 6200 series radically changed recently. The Power Macintosh 6200 in its many Performa variants has one of the worst reputations of any Mac, and its pitifully small 603 L1 caches add insult to injury (its poor 68K emulation performance was part of the reason Apple held up the PowerBook's migration to PowerPC until the 603e, and then screwed it up with the PowerBook 5300, a unit that is IMHO overly harshly judged by history but not without justification). We're not anything on that level of nuts around here. There may be a plan to fork the repository, but they'd need someone crazy dedicated to keep chugging out builds. Unofficially this would be something like the " tier WONTFIX" BDS referenced in a number of years ago. The new state of FirefoxOS, where platform support is actually unwelcome in the repository, is beyond the lowest state of Tier-3 where even our own antiquated port lives. It's not an absolutely clean comparison to us because some APIs are still relevant to current versions of OS X macOS, but even support for our now ancient cats was only gradually removed in stages from the codebase and even some portions of pre-10.4 code persisted until relatively recently. I suppose it shouldn't be totally unexpected given the end of FirefoxOS phone development a few months ago, but a platform going from supported to take-it-completely-out-of- mozilla-central in less than a year is rather startling: not only has commercial development on FirefoxOS completely ceased (at version 2.6), but the plan is to remove all B2G code from the source tree entirely.
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