Steve's SC126 at the top of the charts

[Richard Lewis]

The SC126 Z180 SBC / Motherboard Kit is #1 in the rankings (I'm guessing at the metrics :-)) as scraped from Hackaday. Looks like the Z180 revolution has arrived! 

[Greg Holdren]

I picked one up Saturday myself when I got notice of the restock. :)

Greg

[Karl Albert Brokstad]

It is a very good deal.

Even if it cost, let say $80, it would still be a good deal so we are lucky Steve has managed to keep the price low.

The Z180 contains CPU, SIO, CTC, and DMA. If you were to pick up all of these chips of good quality, they would cost much more than a brand new Z180.

So it makes sense trying to keep the price low. The difference between 32kb, 128kb, and 512kb RAM chips are relatively small.

Karl

[Richard Lewis]

Started building mine last night. Hopefully get to finish it soon. Had most of the parts in inventory so I just bought the board since the kit was sold out. I'm amazed at the difference in price between this and the "other" system at $200. Love the motherboard concept. Wanted something I could easily throw in my bag. 

-Richard

[Nigel Kendrick]

Steve's docs recommend the Z8S18033VSG processor.

Can someone confirm that the only difference between the VSG and VEG variants is operating temp range? From what I gather:

Z8S18033VSG is 0c to +70C and

Z8S18033VEG is -40C to +85C

I appreciate that the VSG part is a little cheaper but it would be good to confirm they are both usable.

Thanks

Nigel

[Richard Lewis]

The "E" designation is for "Extended Temperature Range" otherwise they are identical. I would assume it is for industrial or automotive usage. I have both and have noticed no difference swapping them out. 

-Richard

[Steve Cousins]

Hi Nigel

I'm pretty sure the only difference between the VSG and the VEG parts is the temperature range.

The Z180 series of processors have a history which I haven't fully figured out yet. For example, there is one variant (called SL1960) which is a very old revision. Zilog keeps this available for compatibility reasons. Over the years there have been a number of other functional revisions.

For cost reasons I now use the Z8S18033VSC in the SC126 kit. RomWBW indicates this at startup as revision K. Cost is a big issue with my SC126 pricing. Here in the UK we get to pay a local 20% purchase tax and often get import charges as well. All costs get multiplied up with Tindie fees etc. so it makes a big difference how much I pay for the parts.

The later Z180 revision, which RomWBW indicates at startup as revision N, has some enhancements. These include a larger FIFO on the serial ports, the internal clock multiplier, and software control of the DCD0 function (which SC126 has a jumper for). I think if you buy the Z8S18033VSG, from places like Mouser, you will get the revision N part. So far when I have purchased the VSC version it has been revision N.

In theory, the difference between VSC and VSG is "Environmental Flow". eg. lead-free. However, it appears the available VSC parts are also older revisions.

I've priced SC111 (Z180 module) much higher and this allows me to include the VSG part.

If anyone has more knowledge of the above I'd be interested to hear it. It bothers me that I can't tell the revision when ordering.

Steve

[Marten Feldtmann]

I thought, that the Z80180 is the earlier version and the Z80S180 is the newer revisions with the enhancements you mentioned ...

Marten

[Steve Cousins]

True, but there are also functional changes with different revisions of the Z8S180.

Steve

[Tadeusz Pycio]

Hi Nigel

The first versions of Z180 / HD64180 work successfully on SC111 and SC126 boards. Remember about the right clock and DCD0 to ground. Checked :)

[Stefan V. Pantazi]

I have a Z8S180 related question but on SC722 and SC131 boards. I just tried a Z8S180020VSG part (labeled SL1960, date code 2027 - so very recent if not fake) and it does not seem to work at all. All boards are running great with Z8S18033VSC parts. The 20 Mhz part also seems to be eating up way more current. While 33VSCs need current in the order of tens of mA, the current for 20 Mhz part, on the exact same boards, at 18.432Mhz goes significantly up, in the hundreds of mA. Does it seem like Z8S180020VSG are duds or just incompatible with the boards that work with Z8S18033VSC? Can the boards be made to work with the 20 MHz part or should I just ask for replacements?

Thank you all for the help and for making these boards!

Stefan

[Steve Cousins]

That part should work in SC722 and SC131. There are lots of dodgy Z8S180 series chips about.

[Stefan V. Pantazi]

Thank you for the quick reply, it means it is very likely like the parts I received are duds. I am being sent replacements, no questions asked. But if I did not have means to test immediately what I receive, I would be in some trouble. This approach saved me a few times now.

Again thank you Steve for your amazing work on designing and publishing the documentation for these boards!

[Paul Hunt]

"That part should work in SC722 and SC131. There are lots of dodgy Z8S180 series chips about."

Dodgy as in faulty, or fake?

Cheers, Paul

[Steve Cousins]

My experience has been that nearly all currently available Z8S180 family chips have been re-labelled. They are likely reclaimed components, cleaned up and re-labelled for resale. The label may not correctly indicate the speed rating and within a batch of apparently identical chips there are usually variations in chip version. Most of these components do work. I call these "dodgy" because you don't really know what you are getting or even if they will work. Personally, I wouldn't call the working ones with labels that accurately describe the chip as "fake" but I guess the others might justify that description.

I have to test all Z8S180 family chips before putting them in kits. Fortunately, I still have a large stock of Z80 CPUs and Z80 SIO/2 chips that I purchased from reputable suppliers, such as Mouser. I'm now out of Z80 CTC chips which is a shame. Kits depending on CTC chips are currently listed as out of stock. I may start offering these kits without the CTC chip. Alternatively, I may devise a method of testing the CTC so I can source "dodgy" chips! Not ideal but we can no longer source new production components.

[Doug Jackson]

I automatically report any eBay seller shipping relabelled chips as being fake and not as represented.

We have to convince the suppliers to stop relabelling chips.    I can think of no other way.

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