In the Seagate ST500LM030, Western Digital WDC WD10JPVX-08JC3T5 and HGST HDD HTS541010A99E662 HDDs, what types of memory technology are used to store firmware/BIOS?

pls do yourself a favour: take a look at the pcb and find it out. Pls don't ask any more questions here if you happen to be unable to do that.
:s

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Adatmentés - Data recovery

some ironic answers

The initial bootloader is usually stored on NOR Flash. The "modules" are usually stored on the HDD platters.

some people told me it was NOR or NAND or EEPROM or serial flash
am I confused?

Learn to use Google.
It's usually SPI Flash (EEPROM).

in geral?

A fact is a statement that can be proven true or false based on evidence, observation, or data. Facts are objective, specific, and verifiable; they describe a particular detail or event in the real world. For example, "Post subject: Orico case good or bad?" is a fact because it can be tested and confirmed under specific conditions.

A generality, on the other hand, is a broad statement or principle that applies to a range of situations, rather than a specific instance. Generalities are often derived from patterns, trends, or multiple observations, but they are not always universally true or verifiable in every case. They tend to be more abstract and can lack the specificity of facts. For example, "People are generally social creatures" is a generality; it reflects a common trend but does not apply to every individual in every situation.

Key Differences:
Specificity: Facts are specific, while generalities are broad.
Verifiability: Facts can be proven true or false; generalities are often assumptions or trends that may not always hold true.
Objectivity: Facts are objective; generalities can be more subjective or interpretive.
In short, a fact is an objective truth about a particular detail, while a generality is a broad observation that summarizes a common trend or pattern.

SPI Flash is NOR or NAND?

isn't it an RTFM kind of question?

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Adatmentés - Data recovery

yes