General > General Technical Chat
Clive Sinclair - what a cheap skate!
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wraper:

--- Quote from: Berni on September 05, 2020, 03:10:10 pm ---Because the bad block information lets the controller know not to use those blocks, so if they are not used it does not matter that they are broken, so the flash chips works as intended where anything not marked as bad works. So "patching up bad memory areas" refers to marking them to not be used, not somehow magically fixing them to work again under a microscope or something.

--- End quote ---
Then every NAND chip that comes out of the factory through normal means is "patched up" even though it is not  :palm:.

--- Quote ---In that case the "bad block table" is written on a label on the box of chips.
--- End quote ---
Simply dumb speculation. Chips come in grades and factory does not want to put their own label onto trash grades but bad block table written on the package is something new. Yeah, good luck printing thousands of bad block locations for each chip there  :palm:.

--- Quote ---Or is there a requirement for this bad block correction to be hidden from the end user?
--- End quote ---
No, it is about calling things what they are. You writing they are "patching up" is misinformation. People who read it will think about something very different from what actually happens.
rsjsouza:
Well, a lot has been said about the fab and inherent defects of parts, including modern ones.

My bit is that Engineering is all about making the best thing you can within the boundary conditions you have. With all its problems, Sinclair, Peddle, Tramiel, Wozniak, Mensch, West, Noyce, Kilby, and so many other pioneers were solving issues within the constraints they had.

When I was a teen and started to get involved with the PC world and its "imperfect" hard drives, memories, etc. I also scoffed at the manufacturers for "putting out such garbage" - of course, I quickly realized how naïve I was.

I personally liked two books that talked about these early computing days: Soul of a New Machine (about DEC) and On the Edge (about Commodore).
T3sl4co1l:
Also may be of interest.  I was reading about the latest high density Flash tech that Samsung I think is working with.  It's a stack of layers built up, a terraced hill, allowing them to achieve just a little bit more areal density.  Well, the paper noted how defects can get into that stack, and they can actually tolerate it in some cases as the layers just spread out over it.  Defects might be from dust particles in the fab chamber, for example.  So the layers take on some "princess and the pea" form.  Defects in just the wrong place might cause broken or shorted connections, leaky paths or faulty transistors, sure, but they can actually get an error rate less than one per defect, which makes for a notable improvement to overall yield!

It's like picking up a potato and maybe it's just oddly shaped, or maybe it's got a black spot when you cut into it, or maybe it's a rotten lump.  Sometimes it's fine, sometimes you can cut around it, sometimes it's a total loss.  Whatever works.

Tim
Fraser:
I think we also need to consider the market that Sinclair and others were supplying......not NASA with mission critical systems. The consumer market could not afford CBM PET’s for home use but Sinclair found a way to provide something useful at an affordable cost to many. If people start becoming fussy about chip specifications then they also have to accept a higher cost product will result. It is simple maths and we cannot take away from Sinclair that, even though I dislike it, the ZX Spectrum was a commercial success that also helped many people of my age to enter the world of computers and programming when otherwise we would have remained excluded by cost.

My parents bought me a Dragon 32 and I loved it. I learnt all about its chipset, how to program and how to modify the hardware to suit my needs. Invaluable knowledge to me but I was fortunate that my parents could afford such a computer for me. I could not have afforded a Sharp MZ80 or other more advanced platforms.

Fraser
Berni:

--- Quote from: wraper on September 05, 2020, 03:14:17 pm ---
--- Quote from: Berni on September 05, 2020, 03:10:10 pm ---Because the bad block information lets the controller know not to use those blocks, so if they are not used it does not matter that they are broken, so the flash chips works as intended where anything not marked as bad works. So "patching up bad memory areas" refers to marking them to not be used, not somehow magically fixing them to work again under a microscope or something.

--- End quote ---
Then every NAND chip that comes out of the factory through normal means is "patched up" even though it is not  :palm:.

--- End quote ---

Yep that is exactly what i was trying to say in my first post: https://www.eevblog.com/forum/chat/clive-sinclair-what-a-cheap-skate!/msg3219324/#msg3219324

You can't buy a off the shelf a large capacity raw NAND flash chip that has all blocks working. They exist, but are not binned for it. And if you do get what seemingly looks a perfect array of memory then there is a controller in the mix fixing the bad blocks, such as SD cards where its not uncommon to make 8GB cards out of the bad 16GB flash that don't have enough working blocks to make up a full 16 + enough spare, but don't want to make a 15.9GB card.


--- Quote from: wraper on September 05, 2020, 03:14:17 pm ---
--- Quote ---In that case the "bad block table" is written on a label on the box of chips.
--- End quote ---
Simply dumb speculation. Chips come in grades and factory does not want to put their own label onto trash grades but bad block table written on the package is something new. Yeah, good luck printing thousands of bad block locations there  :palm:.

--- End quote ---

And this is why the NAND chips store the bad block table inside the flash memory itself. The table is very big.

Since Sir Clives "memory controller" could only disable 32KB blocks of memory meant that the bad block table was only 1 bit large, pretty easy to fit on a label, and it was easy to tell this information to the "memory controller" via a simple jumper setting.

EDIT:
Just noticed your addition in your edited post, so il add a response


--- Quote from: wraper on September 05, 2020, 03:14:17 pm ---
--- Quote ---Or is there a requirement for this bad block correction to be hidden from the end user?
--- End quote ---
No, it is about calling things what they are. You writing they are "patching up" is misinformation. People who read it will think about something very different from what actually happens.

--- End quote ---
Noted. Will add clarification to my post.
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