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Tanzania to Tanzania II upgrade

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If I am reading these modifications by Andreas Kann correctly, with the replacement of the crystal at Y2 and swapping of the resistor from R28 to R29 (currently empty), this should tell the motherboard to run at 50 MHz bus speed?


In essence, upgrading the board to a Tanzania II board. Correct?



Would the new clock crystal be something like these?


I suppose if I plop in the Sonnet 500 into this board (testing that it's working first), I wouldn't need to perform the 603e frequency upgrade described on an earlier page of Kann's, yes?



I figure this board is a spare, and already on the chopping block, barring some masterful soldering work... why not try it?


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Okay, upon closer inspection I have a Starmax 5000/225 board... :facepalm:


My bus seems to be configured to tell the firmware I'm running at 50MHz


Can I assume this crystal is 50MHz as well...?



Using Andreas' chart for the 603e "CPU Option" is a multiplier of 4.5. But running at 50 MHz bus that 225 MHz clock, and falls in line with the 5000 series which was 603e based (vs the 5500 which was 604e-based).

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Here's my 4400 board. Sorry no markup, but there's the resistor in the 40mhz position and the crystal has a more distinguishing "40.000" mark.



I'd definitely say the other board I have is indeed a Starmax 5000 board.


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Don't know if I'm out of the woods yet. Sorry for the monologue. If anyone has anything to add, please do.


I figure if I'm in here, I might as well pump up the 5000 board to the 300 MHz limit of the 603ev (small thumbnails: links to full-size)

There's a 51 ohm resistor on R23/R24 but the others are 4.7k ohm
But if we look at the 4400 board for comparison:


Different value on the outlier resistor, as well as a different location (R21/R22) at 3.32k ohm??


Andreas' instructions say to 10k ohm values. Is that because they're cheaper? I'm just curious if the resistance is that different, if it will affect anything on the board. Granted, he's referring to the I-series board, whereas I've got a II...

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I'm gonna tear this off some more [}:)]


1 hour ago, Trash80toHP_Mini said:
1 hour ago, Cory5412 said:
2 hours ago, Trash80toHP_Mini said:

Interesting, I wonder if having something Simply Fast on board might workaround your CPU concerns in overclocking a 6400/6360 board?

Just to be clear here, are you asking if starting with a 6500 /275 or /300 would be more desirable than a G3 upgrade, or?

Nope, that was in response to jessinator's post about pushing the clock of the 6400/6360 bus to 50MHz as he's trying to do in his Tanzania thread. He mentioned 603e complications. I'm wondering if the Crescendo/L2 would negate any possible complications concerning the system CPU as it runs on both 40MHz Alchemy and 50MHz Gazelle architectures.

I've been thinking about this for that G3 upgrade. Sadly, I let that (relatively) local 6500/250 slip away from me. I wondered if there was a way to have one's cake and eat it to with the 6400.

It seems that the 6400 is a slightly more desirable overall architecture compared to the 6500, and wondered if the Bus could be upped to 50 without running into other problems. I haven't looked at an Alchemy board or sone any research, so this is all conjecture, based on Tanzania tinkering.


The Tanzania, stated previously, shows provision in the design to swap a few SMD resitors and caps to work at 50MHz bus. But, as is apparent from the table, depending on how the multipliers are set, it would push the CPU to operate well out of its designed range. At least, doing so on a 200MHz 603e on the Tanzania (and II) would certainly do that, unless you set the CPU resistors to a lower multiplier, say 4.5, for 225 MHz, which is the designed maximum for its particular 603e CPU

All of this, yes, just for getting a Sonnet Crescendo L2 to run at its intended 500MHz :) Again, in all practicality, I have this functionality with my Gossamer G3 MT (has a Sonnet 500 MHz ZIF CPU in it). Again, all for the tinkerz.


I think we did indeed discus the relative, vanilla performance specs of, say, a Gossamer G3 233 or 266 vs a Power Mac 6500/300 as well…somewhere ;) 



Edit, looks like Zone6400 has some blog updates about their tinkering with the 6400 speed and hints that a bus upgrade can be accomplished with a crystal swap…

Edited by jessenator
new information

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The reason I want a 6500/300 specifically is because I want to compare 603e performance to 604e performance and G3 performance.


I wouldn't mind grabbing a 300MHz G3 chip for my blue-and-white either just to add a fourth datapoint, mostly to show how much platform enhancements help.


I already have an 8600/300 and a Beige G3/300 and the Beige G3 outruns the 8600 by a country mile.


If you don't care about adding certain PCI cards, the easier solution is to get a 6500/225 or /250 (I'll argue that /275 and /300 boards should be left alone) and put your G3 upgrade there. It sounds like the big hang-up with the 6500 might specifically be ATi video cards (because it has an onboard Rage II variant) and multi-function cards (like the tempo trio, which jt likes because of its multi-functionness.)


I haven't seen (or don't remember) notes about just-SATA or just-IDE in the 6500, so that might be A Thing to be aware of.

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I think I'm one of those weirdos who would rather have a Rage128 in every PCI mac :P I actually just acquired a 4MB module for the beige G3 MT.  And so far I haven't minded the on-board video in the 4400 now that I can use something larger than my 13" AppleColor display: I also acquired a Radius Pivot cable, which works a treat connecting my D-15 mac connectors to my SVGA Sony LCD. In that transaction I received a ViewSonic dip-siwtch adapter as well as the Apple D-15 female to SVGA male adapter, but the cable has put them both out of work :) 


I do kick myself a little for not getting that 6500/250+monitor+goodies... oh well, onward and upward. Thought about buying OleLila's 6500, but shipping that would be a pretty penny, though it does seem a nicer deal, cosmetically, than what's on ebay... I can be patient I guess.


I think my main crossroads now is what to do with my Starmax 5000 board. Part of me wants to modify the 4400's case to accommodate it (the PS/2 ports I think are adding just enough to not align with the board pins), and slightly widening the video cutout on the i/o. I mean, it's not a stock 4400 now anyway, what with the PSU substitution and industrial hook-n-loop attached battery holder. Using the Starmax board would alleviate my need for a 64/6500 anyway.

Edited by jessenator

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