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Source for last generation L88M m68040?

johnklos

Well-known member
I started an archiving project using a Mac Quadra 610 here:

https://68kmla.org/forums/index.php?/topic/25007-starting-archiving-project-using-quadra-610/

However, the 50 MHz NewerTech Quadra Overdrive proved to be not all that stable. The rest of the machine is 100% stable running at 25 MHz without the Quadra Overdrive, and I'd like to fix that.

Does anyone know of a source or sources of the last mask .57 micron L88M Freescale / Motorola chips, aside from the $50 ones on eBay?

 

ArmorAlley

Well-known member
Hi John,

It's funny that you mention this. I have a Quadra Overdrive in my Performa 475 and it does behave erratically every now and then. It also blocks the network card. I installed AppleShare 4.0 on the P475 and the two don't play nicely together.

Thanks for the confirmation.

 

techknight

Well-known member
probably because the processor is a little bit too fast and not enough wait states for the bus = bad. 

 

360alaska

Well-known member
If the cpu is removable on the accelerator card, then why not just pop it into the quadra and swap the onboard oscillator. It won't be as fast but at least it's faster than what you got...

"Quadra 610

The 25 MHz Quadra 610 replaced the 20 MHz Centris 610 and uses the full 68040 CPU, not the FPU-free 68LC040 version. The oscillator runs at 12.5 MHz and the CPU at twice that internally, 25 MHz. Using a 14.7456 to 15 MHz oscillator will boost speed to 29.5 to 30 MHz while allowing the serial ports to continue to function properly.

If you don’t need to use the Mac’s serial ports, you can over clock the 610 to 37 MHz with an 18.5 MHz oscillator. You can drive a Quadra 610 with DOS card to 34.9 MHz using a 16.96 MHz oscillator."

- From Low end mac

 
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johnklos

Well-known member
techknight:

The Quadra Overdrive doesn't change the number of wait states at all. It runs the processor at 50 MHz when the bus is relinquished by the motherboard. Everything else runs at the same, standard 25 MHz.

360alaska:

I could do that, but I'd rather get a cool, even more overclockable m68040 and run it at 50 MHz and keep the rest of the system at the standard speed for best stability. This system has had uptimes with heavy usage of many months, and I want to get back to that level of stability.

 
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techknight

Well-known member
techknight:

The Quadra Overdrive doesn't change the number of wait states at all. It runs the processor at 50 MHz when the bus is relinquished by the motherboard. Everything else runs at the same, standard 25 MHz.
And thats exactly what I meant. it has to insert wait states for the bus to catch up. some peripherals dont like excessive wait states. And you cant relinquish the bus unless there is RAM, and ROM, and CACHE onboard the accelerator. Then you need a DMA interface in order for that to even think about relinquishing a bus. 

 
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johnklos

Well-known member
techknight:

It's much, much simpler than that. Whenever the m68040 is talking to the motherboard, it is running at 25 MHz. Whenever it isn't, it's running at 50 MHz. This is why purely synthetic benchmarks such as dhrystone show 50 MHz speed - the whole main loop of the benchmark fits in the m68040's caches, so 99% of the time the benchmark is running, it's running at 50 MHz. There are no wait states - just slow states ;)

rsolberg:

I bought one a while back, but when I installed it, I immediately knew it was a counterfeit because it was an LC040. I got my money back, but I'll definitely check any I get in the future. 

Aside from seeing how hot the chip gets, I don't know if there's a way to verify that it's a late mask - errata all appear to have been fixed in the E71M and E42K masks. Hmmm...

Also, I didn't go with that seller because of the ridiculous shipping price, although I was going to make an offer, but instead I got mine for $55 USD shipped.

 

johnklos

Well-known member
http://www.ebay.com/itm/MC68040RC40A-Manu-MOT-FREESCAL-Package-PGA-32BIT-W-CACHE-MMU-FPU-/201024477214

40MHz version.... but it's from China.  Could be legit, old stock.  Could be counterfeit.  Couldn't tell ya.
That's the E42K mask, which is .65 micron - you can see the mask printed in the corner of the chip in the photo. The E42K mask is better than the original masks which came in Macs, but it's not as cool as the L88M mask (.57 micron), which also has the die mounted differently to better dissipate heat.

 
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rsolberg

Well-known member
I was watching the 40MHz ones from China, but passed due to the earlier mask. If you're interested in the ones I linked above, ask the seller for a shipping quote. The calculator on that listing seems out of whack. I ended up paying about $10 for shipping, albeit within Canada. The unit I received is definitely as marked- it runs markely cooler than the XC68LC040 it replaced and is identified as a MC68040 in software, FPU benchmarks run properly. I think this unit is circa 2006 as it has the Freescale logo in place of the Moto 'M'. I thought I was going to need a heatsink, but the top of the package doesn't seem to break 40C under load.

 

olePigeon

Well-known member
So are the newer models more desirable because of the heat dissipation?  Better overclocking, or what?

 

Paralel

Well-known member
I wonder how difficult it would be to replace the processor on a 550c daughtercard with a newer model. Its current processor is one that is period correct, so it generates quite a bit of heat. Something cooler would be nice.

 
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johnklos

Well-known member
The newer models are made with a newer mask, meaning they draw less power, generate less heat and should be more overclockable. Most people say they get warm but not hot to the touch, even without a heat sink. Since I want to run mine at 50 MHz 24/7/365, I want the coolest, most stable one possible.

Paralel: Yes, you can. They're cheap, too:

http://www.ebay.com/itm/MMPN-C68040FE25-Manufacturer-MOTOROLA-Encapsulation-QFP-32-BIT-W-CACHE-MMU-/181813260936?hash=item2a54ea3288:g:x5UAAOSwT6pVkfVg

Make sure you get an MC68040FE without a "V" at the end. The "V" signifies a 3.3 volt chip instead of 5 volts. You'll have to find someone who can desolder and resolder a 184 pin QFP chip.

 

MrFahrenheit

Well-known member
Just bought one from this seller and installed it yesterday. As noted in description, specify in comments that you want an L88M. Shown below installed in my CC.

http://pages.ebay.com/link/?nav=item.view&id=111633589714&alt=web

View attachment 2679

I apologize for resurrecting such an old thread.

I just received two 68040 “L88M” CPUs on eBay. I posted about it in the “L88M” thread. Here are two photos.

I was immediately drawn to the surface texture on the CPU package. It feels almost like plastic, compared to every other 68040 I’ve handled (which almost feels like steel or glass). Looking at your photo it looks similar to the surface texture on mine.

Do you recall the top surface feeling any different from your other 68040 CPUs?
 

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MrFahrenheit

Well-known member
I’ve updated in the other L88M thread here.

It’s highly suspicious. But what’s weird is the gold cap on the bottom is the largest of any 68040 CPU I have seen. I have revisions of 68040 of nearly every type from .80 micron, 0.65 micron and 0.57 micron. None are as large on the bottom as these.

Here’s a close up of the problem. Either Freescale changed their labeling technique or these have been faked.

What’s strange is the age of it (2009?) would put it at MOS11 plant, in Texas. If so, why would it say Malaysia?

Testing it at only 33mhz, the thing is the hottest of all 68040 CPUs I have, coming in at over 80’c.


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Melkhior

Well-known member
The funny thing about the 68040 is that it is technically still in production. Unfortunately most variants (including the RC40 I linked to) are only available BTO, and the in-stock ones are rather expensive - eBay prices still have a lot to learn from specialty silicon manufacturers :)
 
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