Bubble Memory
en.wikipedia.org
Bubble Memory
1–10 of 30 posts
Re: Bubble Memory
#2I find pretty interesting that the memory is not perfect out of the fab and its defects are coded on its label, hence these defects can be loaded to the device using it as a map, so it can work around these loops while working.
Now, this is even true for flash memory, but this is handled at the controller level and its dynamic during its initial "formatting" at the factory, so it's completely hidden from the host unless "host" is the controller.
OTOH, bubble memory comes with a "this machine has no brain, use your own" sticker on it.
Re: Bubble Memory
#3Thanks for the in-depth explanation of this system. One of the most mainstream and famous use of bubble Memory may be the Gradius (Konami) shoot them up PCB and its infamous loading/warmup screen.
Re: Bubble Memory
#4I find pretty interesting that the memory is not perfect out of the fab and its defects are coded on its label, hence these defects can be loaded to the device using it as a map, so it can work around these loops while working. Now, this is even true for flash memory, but this is handled at the controller level and its dynamic during its initial "formatting" at the factory, so it's completely hidden from the host unl…
Hard disks used to come with a paper label listing their bad sectors. (They still come with a list, it's just now it is hidden in the firmware like you describe.)
Re: Bubble Memory
#5I find pretty interesting that the memory is not perfect out of the fab and its defects are coded on its label, hence these defects can be loaded to the device using it as a map, so it can work around these loops while working. Now, this is even true for flash memory, but this is handled at the controller level and its dynamic during its initial "formatting" at the factory, so it's completely hidden from the host unl…
Not nearly all flash systems (including NAND based ones) use a dedicated controller. I believe e.g. iOS devices have for a long time still handled bad block handling in software, while macOS has always handled it in hardware.
Re: Bubble Memory
#6I find pretty interesting that the memory is not perfect out of the fab and its defects are coded on its label, hence these defects can be loaded to the device using it as a map, so it can work around these loops while working. Now, this is even true for flash memory, but this is handled at the controller level and its dynamic during its initial "formatting" at the factory, so it's completely hidden from the host unl…
Hard disks used to come with a paper label listing their bad sectors. (They still come with a list, it's just now it is hidden in the firmware like you describe.)
And the firmware remaps them, as far as I know. That's very different from a firmware exposing a bad sector list to the host, which is the case for some flash systems, I believe.
Re: Bubble Memory
#7See also: https://en.wikipedia.org/wiki/Ferroelectric_RAM, which has been used in a few quite popular systems as well (e.g. the PS2 memory card supposedly uses it for some high-rewrite-count operations).
Re: Bubble Memory
#8See also: https://en.wikipedia.org/wiki/Ferroelectric_RAM , which has been used in a few quite popular systems as well (e.g. the PS2 memory card supposedly uses it for some high-rewrite-count operations).
FRAM is also used in all modern MSP430 microntrollers from Texas Instruments. Amazing technology
Re: Bubble Memory
#9Earlier quoted context omitted.
Hard disks used to come with a paper label listing their bad sectors. (They still come with a list, it's just now it is hidden in the firmware like you describe.)
And the firmware remaps them, as far as I know. That's very different from a firmware exposing a bad sector list to the host, which is the case for some flash systems, I believe.
Disk firmware follows sectors which are hard to write, flags them as "current pending sector". Then reallocates that sectors data to one of the reserves when it has time and increases "Reallocated Sector Count", and if it deems the sector dead or unusable, it's get blacklisted and "Offline Uncorrectable" count is increased as well, from what I remember.
This is all transparent from the host, maybe an occasional "wait a little, I'm kinda busy" signal to the controller. Same for flash, but it's way faster and more transparent, since the real map inside the flash controller is never linear, anyway.
Re: Bubble Memory
#10I find pretty interesting that the memory is not perfect out of the fab and its defects are coded on its label, hence these defects can be loaded to the device using it as a map, so it can work around these loops while working. Now, this is even true for flash memory, but this is handled at the controller level and its dynamic during its initial "formatting" at the factory, so it's completely hidden from the host unl…
Not nearly all flash systems (including NAND based ones) use a dedicated controller. I believe e.g. iOS devices have for a long time still handled bad block handling in software, while macOS has always handled it in hardware.
Systems running macOS (i.e. Mac systems) use SATA or NVMe disks (depending on their age) which come with their own controllers, hence it's always isolated from the OS except SMART data. I have no idea about iOS systems.
Controller based management is also true for SD cards of any form, CF cards, USB flash drives or any external drives. This makes only embedded systems and devices like phones with direct NAND/NOR management AFAICS.