Electronic – Why are EEPROM sizes measured in “k” or kbit and not kbyte or byte

datasheeteeprom

I keep seeing EEPROM datasheets using terms such as 4k, 16k, etc. and they're referring to 4 kilobit and 16 kilobit, bits, megabits, and kilobits are often used. Very seldom do they use byte prefixes. Some will also clarify with 512 * 8 bits, or 2048 * 8 bits.

Why isn't using bytes (or kilo-/mega-) preferred, as there's always 8-bits in a byte, and I've never heard of EEPROM that can't be divided into bytes.

I realize that kbit/Mbit is used in data communication, but I don't understand the relation because EEPROM is technically storage, not bandwidth. This applies to EEPROM, but also other similar types of memory like Flash or SRAM, etc.

Best Answer

  1. The marketing department got there first.

  2. Because they can.

  3. To some extent, knowing how many bits you can store has some value as EEPROM may be used for bit or nibble or ternary or Klingon-base-xxx storage. BUT most engineers can multiply by 8 and divide by whatever quite well so expressing it in bits has no vast value.

1 & 2 can translate to "it sounds better and we may sell more". It doesn't and they won't, but hope dies eternal in the marketing department.

Some systems use other than 8 bit word widths so expressing in bits may make sense, but this is not usually a good enough reason. If you are using an Intersil 6601 CPU to build a DECMATE PDP-8 'compatible you may wish to use 12 bit words (but you'd be about 30 years late :-) ). Otherwise using "bytes" where word size is 8 bits, or "words" where word size <> 8 bits, are just as useful or more so than bits.