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| Clive Sinclair - what a cheap skate! |
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| wraper:
--- Quote from: Berni on September 05, 2020, 01:37:12 pm ---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, packaging them into chips and selling it. --- End quote --- Not true, NAND is used as is. Controller deals with bad blocks of memory. Crappiest tier NAND usually goes into cheap memory cards or toys. Micron has their own division called Spectek which deals with dodgy Micron NAND and DRAM. Usually you can find S logo placed over original marking. They even sell chips with 3 lines on them for especially dodgy stuff. |
| Berni:
--- Quote from: wraper on September 05, 2020, 01:47:03 pm --- --- Quote from: Berni on September 05, 2020, 01:37:12 pm ---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, packaging them into chips and selling it. --- End quote --- Not true, NAND is used as is. Controller deals with bad blocks of memory. Crappiest tier NAND usually goes into cheap memory cards or toys. Micron has their own division called Spectek which deals with dodgy Micron NAND and DRAM. Usually you can find S logo placed over original marking. They even sell chips with 3 lines on them for especially dodgy stuff. --- End quote --- Yes later on flash manufacturers started doing it themselves since it provides profit out of junk. And yes its the controllers job to fix bad blocks, but the bad block information is stored in areas of the flash chip itself and the manufacturer might grantee an area of error free blocks for holding bootloader code (This is more for embedded systems, not SSDs). For example from the datasheet of a random Micron flash chip of MT29F8G08FACWP: |
| Andie:
--- Quote from: sleemanj on September 05, 2020, 01:42:38 am ---[...] Now if you want really dodgy, Amstrad (I think it was Amstrad) fitted completely fake ram and circuit board onto their computer to sell it into, I think Spain, or Portugal, which had a minimum memory requirement, the ram they fitted was completely bogus not connected in any meaningful way to the computer electrically! --- End quote --- Here is some further read in the eevblog forum: https://www.eevblog.com/forum/vintage-computing/the-dodgiest-computer-ever-!/msg3109666/#msg3109666 |
| wraper:
--- Quote from: Berni on September 05, 2020, 02:19:01 pm ---Yes later on flash manufacturers started doing it themselves since it provides profit out of junk. And yes its the controllers job to fix bad blocks, but the bad block information is stored in areas of the flash chip itself and the manufacturer might grantee an area of error free blocks for holding bootloader code (This is more for embedded systems, not SSDs). For example from the datasheet of a random Micron flash chip of MT29F8G08FACWP: --- End quote --- So how storing bad block information qualifies as "to patch up the bad memory areas"? :-//. Factory may sell crap with no or little testing and testing done later by 3rd party but NAND chip still is as is with nothing bad hidden or fixed. |
| Berni:
--- Quote from: wraper on September 05, 2020, 02:55:23 pm --- --- Quote from: Berni on September 05, 2020, 02:19:01 pm ---Yes later on flash manufacturers started doing it themselves since it provides profit out of junk. And yes its the controllers job to fix bad blocks, but the bad block information is stored in areas of the flash chip itself and the manufacturer might grantee an area of error free blocks for holding bootloader code (This is more for embedded systems, not SSDs). For example from the datasheet of a random Micron flash chip of MT29F8G08FACWP: --- End quote --- So how storing bad block information qualifies as "to patch up the bad memory areas"? :-//. Factory may sell crap with no or little testing and testing done later by 3rd party but NAND chip still is as is with nothing bad hidden or fixed. --- End quote --- 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. So same thing as Clives RAM chips that arrive with defects. Its perhaps even possible that he got the manufacturer to separately bin the chips with the high or low half failing into separate boxes. In that case the "bad block table" is written on a label on the box of chips. Or is there a requirement for this bad block correction to be hidden from the end user? Like for example modern HDDs that do bad block remapping inside the HDD controller chip while showing a perfectly linear array of always good sectors on the SATA interface. |
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