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Clive Sinclair - what a cheap skate!
T3sl4co1l:
If the parts were actually useless, they would've been trashed. The fact that they were sold and used is proof that they weren't useless.
Not that unscrupulous sellers don't exist either, but again, see above. When there are regulatory forces in place to prevent that, you get a well functioning market.
There's plenty of history of this, of actually trashing parts that don't meet spec. Manufacturers aren't afraid to do it. There are plenty of photos of, for example, mounds of finished vacuum tubes, to be crushed and disposed of (or hopefully recycled?). Selling dysfunctional parts would be more harmful to their reputation than the value of those parts, even if sold through appropriate channels (or indeed, the cost of setting up that "budget"/off-spec/relabel sales channel wouldn't be worth its revenues).
A better concern would be if they were reliable, at whatever capacity they had. I don't know about the chips in question, but it's generally the case that semiconductors don't change much over time (aside from exposure to ESD, which is avoidable in finished products by appropriate design). It's a good guess that, within that available capacity, they're fine, functionally indistinguishable from a chip of the same (design) size. That is, the defect happens to cause a few memory bits, or cells, or decoders or whatever, to malfunction, but the rest of the chip is and shall remain perfectly functional aside from that.
I don't know what's difficult about understanding that.
It's like I sold you a car that, by all indication is supposed to have a 4-cylinder engine in it, but I actually put in a V8, but I did a shitty job tuning it so it only makes the power of a 4-cylinder anyway (and yes, assuming other circumstances are comparable, like equal mileage -- maybe it's just not getting enough fuel or something, so it's somehow just as efficient, but only delivers half max power). And you're complaining that I've somehow defrauded you, but you're getting a car exactly as described.
Tim
Ian.M:
He was sold half-working 64Kbit DRAMs at a significant discount, certainly less than the price of two 16Kbit DRAMs. If he'd been a little bit cleverer, he'd have figured out how to use 48K of them and do away with the bank of 16Kbit DRAMs that comprised the base 16K as mostly the defects would have been quite localized, so if they'd been tested and binned by defect page, with two XOR gates on DRAM A6 and A7 and two jumpers to select which 16K page not to use, he could have used 3/4 of each chip. However he'd already maxed out the 40 pins of the ULA, I'm not sure if it had enough gates left, and it would have impacted performance as all the RAM would have been contended with the ULA video controller. The refresh design might have also been a bit hairy as natively, the Z80 only provides a seven bit refresh address. Maybe Clive wanted to do it that way and either the pressures of time to market, or Richard Altwasser's good sense killed it off.
Monkeh:
And if you think that doesn't go on today at the fab level, you're kidding yourself.
We all know the basic structure of DRAM - one transistor and one capacitor per bit. Not including muxes and all the other supporting circuitry. So I just added up all the RAM in my daily-use x86 machines, excluding GPU VRAM, phones, tablets, and so forth. 126GiB of it. One trillion, 82 billion, 331 million, 758 thousand, 592 transistor/cap pairs, if my math isn't off.
Somehow, I suspect I've got quite a bit of unused partially-faulty DRAM around me. Just a feeling..
Oh, and all those cheap off-brand (or just lesser brand..) SSDs out there with no markings or custom markings on the flash? Parts which failed to meet OEM specs. Sold off, tested (maybe..) to much lower standards and sold to you.
wraper:
Basically all modern DRAM, NAND and camera sensors have faults in them. One in a thousand of chips might have no defects at all. DRAM defects are hidden on the chip level by using spare rows/columns. Or even half of the chip may be disabled and sold as smaller size. NAND defects usually are managed on controller level. Camera defects are dealt with in image processing software. CPUs/GPUs often have parts of them disabled to increase yield and sold as lower tier parts. Some have some part disabled even in the top tier chip. Say PS3 CPU has 8 cores physically but one of them is always disabled to increase yield.
Berni:
--- Quote from: CJay on September 05, 2020, 11:50:08 am ---
--- Quote from: Berni on September 05, 2020, 11:37:16 am ---Its pretty common for companies to sell partially working silicon chips for cheaper in order to avoid just tossing them in the trash.
Pretty much all the SD cards you have contain just partly working flash inside. Due to the push for density the yield is awful on flash memory. So even the top tier cards have some leftover capacity hidden away to cover the dead pages. The chips with too many dead areas are instead sold as half capacity memory chips.
AMD used to sell 3 core CPUs. Why would they make a 3 core chip? Because these are actually 4 core chips with one of the cores dead, but the chip is designed to easily disable that core.
Nvidia does this commonly where the xx70 models (2070 1070 970...) are actually the same GPUs that are used in the higher xx80 models(2080 1080 980...) except that too many cores are dead, so they disable a certain number of cores and sell it off as the lower model.
Even 100% working chips are binned. For example intel sells the same CPU die under multiple partnumbers depending on how well it did on the final test stage. If a chip is seen to perform better under high clock speeds it is sold as the overclocking K variant, if the chip fails the test at normal speed but passes the test at a lower clock speed then it is sold as a lower clocked model. If a chip shows particularly low power usage then it is sold as the low power S or T variant.
--- End quote ---
This is all by design though, Sinclair bought parts which would otherwise have ended up in the trash.
--- End quote ---
Well this is done with flash too.
Some flash silicon come off the manufacturing line so bad that the actual manufacturers like Micron, Samsung..etc don't want to bother with it. So there are companies out there that make it a business of buying the crap flash dies from the big players on the cheep. Putting them trough more extensive testing to patch up the bad memory areas[Note 1], packaging them into chips and selling it.
A lot of of the really cheep off brand SSDs have such waste reclaimed flash in them.
EDIT:
Note 1: To clarify expressed concerns for confusion, this process of "patching up bad memory" involves writing down the block as being bad by writing this information into the flash memory before it leaves the factory. This does not involve somehow repairing the incredibly tiny silicon structure on the die.
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