Upgrading a Daystar Turbo 601 for IIci from 66MHz to 100MHz - Success!

[willmurray461]

I was able to upgrade my Daystar Turbo 601 (PowerPC 601 upgrade for the IIci) from 66MHz to 100MHz!

I followed this guide: http://www.applefool.com/clockchipping/dt601.html.

HOWEVER! I made a few changes...

The above guide overclocks the original PPC601 CPU and does not replace it with a faster one. The PPC601 was never meant to go beyond 80MHz, so overclocking won't get you very far.

Instead, I bought a NOS 601v off of eBay rated for 110MHz. The 601v was made in speeds up to 120MHz, so perhaps a 120MHz mod is possible. Theoretically, you could also salvage a 601v from a donor Mac, but desoldering 601's is usually pretty tricky. Unlike the 601 though, the 601v needs a 2.5v core voltage compared to the 601's 3.6v.

I followed the original guide step-by-step, but also desoldered the original 601 CPU and replaced it with the 601v using a hot air station.

Because of this, you need to add one additional step. You must move R14 (107 ohms) to R15 (originally 200 ohms), and place a 90.9 ohm resistor in R14. This will make the regulator output 2.7v instead of 3.6. I didn't have a 90.9 ohm resistor, so I opted to put 100 ohm resistors on both R14 and R15, which should have the regulator output 2.5v.

 

[zigzagjoe]

Nicely done! I have one of these I will have to someday try that on.

Curious, though - I checked through the 601 datasheet and found the following blurb. I'd assume you're running VDDio at the same as the core since earlier boards probably used the same supply for each... seems like this could be a potential problem. But it might just be motorola covering their rear for the conditions they're willing to specify 100mhz operation at.

 

[Joopmac]

cool!! would something like this apply also to a quadra pds version?

 

[willmurray461]

Nicely done! I have one of these I will have to someday try that on.

Curious, though - I checked through the 601 datasheet and found the following blurb. I'd assume you're running VDDio at the same as the core since earlier boards probably used the same supply for each... seems like this could be a potential problem. But it might just be motorola covering their rear for the conditions they're willing to specify 100mhz operation at.

I'm pretty sure the part of the mod where you move around a bunch of large 0 ohm shunt resistors switches the I/O supply from 3.6V from the regulator to 5V from the PDS since the 601v uses 5v for I/O. I haven't confirmed this myself though. Anyway, I already have a 100MHz card, and can confirm that after the mod is complete, the above instructions will make a 66MHz card identical to a 100MHz one, so either way I think it's fine.

cool!! would something like this apply also to a quadra pds version?

You could add a PPC601v to a Quadra card, but the Quadra PowerPC 601 card doesn't have an empty footprint for the ICS9178 clk gen IC like the Turbo 601 does. As such, you'd be stuck with x2 clock (no x3 or x4), hence making such an endeavor pointless since the normal 601 can already go up to the max for x2 (40MHz x2 = 80MHz)

 

[zigzagjoe]

Oh, the original cards also used a 601v on the 100mhz version? I admit I'm not up on much of the PPC stuff. It makes sense then that they'd have a bunch of shunts to change the IO voltages then.

 

[eharmon]

Oh, the original cards also used a 601v on the 100mhz version? I admit I'm not up on much of the PPC stuff. It makes sense then that they'd have a bunch of shunts to change the IO voltages then.

If I remember correctly, there wasn't a 601 @ 100MHz. Required a change to 601v.