Advice on 68060 purchase wanted

[alexh]

There is really only one 68060 worth buying and that is an MC68060RC50 with mask E41J.

These were the last of the 060's to be produced. They are a much lower geometry than the others meaning they clock very easily upto 90MHz.

All the RC60 and RC75 chips are AFAIK earlier chips at a higher geometry which are not quite as good. It is this E41J mask which is the important bit. As long as it has that marking it will run well.

Don't forget you need FAST memory too... 50ns SIMMs recommended.

[alexh]

If all he wants is 60 or 66Mhz, why would he hunt down a processor that would sell for a premium?

Because some RC60's are EC meaning they don't have a working FPU. I think all RC66's & RC75's are EC and have no working FPU. They may have FPU in them, and some may have an FPU which works at 75MHz but the EC means they were sold as not having a FPU. Some are LC meaning no FPU or MMU. It is a minefield.

An RC60 can be had for under $90 (if you're not worried about the revision).

You can get an MC68060RC50 E41J for $90 if you wait a short time. Plus the peace of mind that it has both an FPU and MMU and clocks to 60MHz without heatsink or fan.

[alexh]

Out of interest how do you go about replacing the processor on a Blizzard 1260?

Desolder the 040 CPU, solder in a socket or the 060 CPU directly. Add a new ROM. Add a power regulator. Change several jumpers for power and clock frequency.

Cosmos had a entry on his blog.

http://cosmosamiga.blogspot.com/2010/02/apollo-1240-1260.html

[alexh]

This guy... but he's not selling any at the moment

http://feedback.ebay.co.uk/ws/eBayISAPI.dll?ViewFeedback2&userid=banshee121&ftab=AllFeedback&myworld=true

[alexh]

If you or Franko can find some references that lists each mask by features it could prove very useful.

It doesn't work that way.

The only thing really changes between mask sets are geometry and bug fixes. The lower the geometry usually the less heat the part produces for the same clock speed and voltage and thus the easier it overclocks.

0.60um 1F43G Mask Product information
0.60um G65V
0.42um LC/EC G59Y
0.42um 1E41J
0.32um 71E41J

I think what you want to know is how the product code listing works?? The MC, XC, LC, EC, RC, FE, A etc. works??

http://www.motorola.com.cn/semiconductors/mcudsp/forms/selector_guide/sg186_Std_Embedded_Controller_rev9.pdf

Right now the only one you've mentioned that I can be sure has an FPU and MMU is the MC68060RC50 E41J.

That is your best candidate for overclocking but it is not the only one. If it doesn't have EC or LC in the name then it has both FPU and MMU

But I'd also like some info on RC60, RC66, and RC75 masks.

Doesn't work that way. MC68060RC50, MC68060RC60, MC68EC060RC66 and MC68LC060RC75 *may* all be the same mask set. (i.e. the same chip) but they are badged differently because they have faults in the MMU or FPU which prevent them running at the quoted speed (or at all). If you follow the 68060 though you can see that some EC/LC chips are made with G59Y mask which physically have no FPU

[alexh]

And I assume ideally I'd want a non EC RC60 with a 0.32um 71E41J mask.

Or a non EC RC50 as they will probably be cheaper.

They are exactly the same chip inside. Just one has been selected (possibly on die characteristics) to be marked as RC60.

However E41J RC50's are proven to overclock easily to 90MHz so running at 60MHz will be no problem.