NOS trays of Next Turbo ASICs

Started by barcher174, January 24, 2020, 04:55:46 PM

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barcher174

Sometimes with patience, miracles can happen:



I located 2 trays of both turbo ASIC chips. Those boards that you recap and they still flash random blink codes? Probably the ASIC.

t-rexky

Well, all I can say is that this is almost surreal!

Rob Blessin Black Hole

Hello Brian:  I know ASIC's stands for Application Specific Interface Chip as a general term and these ones are for Turbo Systems. It would be cool to hear how they function as part of NeXT hardware as this is your area of expertise. How do these differ from the earlier motherboard configurations?
 I've heard from Mike Perka a NeXT engineer that a lot of the later changes to the Turbo boards were part of cost cutting measures by NeXT to bring hardware costs down. The later Turbo Boards were "cheaper" to manufacture, so when we come across a 68040 25Mhz boards on a Turbo MotherBoard this was in effect "cheaper" to manufacture than the earlier 68040 25Mhz Non Turboboards.
 Some of the cost cutting measures went to far in my humble opinion like the all plastic ram connectors on Color Motherboards verse the ram connectors with the metal holders. You have to be very careful removing ram from the plastic ones because the have become brittle.
Where I was going with this, is we seem to be seeing more issues like the blinking lights from faulty ASIC's and failed leaky caps on the later boards due to hard component failure. So it seems the cost cutting measures of old engineering are finally catching up in terms of longevity of motherboards etc... not only on NeXT but all platforms especially with the now industry standard planned obsolescense.  I think NeXT does outshine the old pack in a lot of ways even their cost cutting components for the most part were upscale. 
In today's market , A lot of straight up counterfit garbage on the market, even in terms of replacement components coming from trusted vendors, ha don't even get me started on my failing high end appliances and the shrinkng replacement cycle.
One thing I do really appreciate is the quality of Apple Hardware, it is rock solid for the most part ..... thank you for keeping these NeXT's going it is awesome.
One final note I had a 68040 25Mhz Cube board socketed with a labeled 68040 33Mhz Processor , it works but only registers it as 68040 25Mhz at any rate . I know I'll need  few of those ASIC's to mend Turbo Boards nice save! 
Rob Blessin President computerpowwow ebay  [email protected] http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community  since 2/9/93

barcher174

Ok, you asked, so I'll ramble a bit. The function of the turbo asics vs the nonturbo is largely the same. One key addition is the ADB input. The next engineers really built a brilliant system for the day. All core functionality is shared between these 2 chips which is why the board design looks so clean. Unfortunately we have no datasheets so its hard to say what is going on internally unless someone does a destructive delayering. I can comment generally about the progression. The initial packaging would have been very expensive. It's really high quality with nice gold plating. You can de-lid the package and see the silicon wafer inside, but theres not much visible through the top metal layer of the die. The only markings are the same part numbers which appear on the lid. Mostly when these break I see physical damage to the chip. The nextstation boards use the same chips as the cube. In my early investigations I even got an MO drive working with a station. As the board revisions get later we see plastic packages replace the ceramics(even before the turbo models). These would have been significantly cheaper to produce. I do wonder about the volume of packaged parts that were made given the expectations they had for machine sales(which we now know they never remotely reached). Packaging is only one variable in the cost function of manufacturing, but certainly would be attractive given the surface mount focus of the automated assembly line. I could also assume that there was a die shrink between 1988 and 1992. Lets greatly simplify this to say that when things get smaller you need less materials, so price goes down(neglecting process fees). There are other advantages like transistor switching speed which allows you to raise the overall frequency. Say to clock from 25 to 33mhz system clock (which is divided from a faster clock). Faster clocks mean more heat(once again greatly simplifying). Also they switched from ceramic with superior thermals to plastic. So now heat becomes a problem. Manufacturing tests at the time would have been based only on stuck methodologies. Basically check some Pregenerated patterns for nodes that are stuck to vdd or gnd. Today we use various fault models including @speed testing. We're looking for multiple things: shorts, opens, timing faults among others. Back to the Turbo asic. Aging defects in silicon can be thought of as borderline manufacturing abnormalities. They can pass a stuck test with flying colors. Then in the presence of heat and time there is drift to where a hard defect can be observed. Today we use a combination of at frequency testing and manipulation of the input voltages to try to show these behaviors before the silicon ever gets packaged.

TLDR: Basically I'm saying we should probably start putting heatsinks on these chips.

barcher174

I had a chance to use a couple of these chips today. I can confirm they are genuine and working. It's so much nicer dealing with straight pins! I think it literally cut the time in half.

tpfaff100

Somewhere, I have a box of NOS Next Color Turbo badges.

barcher174

Quote from: tpfaff100 on October 04, 2021, 02:37:21 PMSomewhere, I have a box of NOS Next Color Turbo badges.

It's amazing to me how few turbo badges/cases I've seen compared to the number of logic boards.

MrPix

Since these two ICs are what is needed to make new machines, it *might* be worth it to do a new design of board using more modern RAM and make a very slick run of absolutely top notch memory and options systems.

It is a possibility, now the NeXT schematics are in the world.