Write ability and storage permanence of memories:
Write ability is the manner and speed at which memory can be written.
Storage permanence is the ability of memory to hold stored bits after they are written.
Ranges of write ability:
The processor writes to memory simply and quickly. E.g. RAM
The processor writes to memory, but slower. E.g. Flash, EEPROM (Electrically Erasable and Programmable Read Only Memory)
Special equipment,"programmer" must be used to write memory. E.g. EPROM, OTP ROM (One Time Programmable Read Only Memory)
Bits stored only during fabrication. E.g. Mask-programmed ROM
In system programmable memory
Can be written to by a processor in the embedded system using the memory.
Memories in high end and middle range of write ability.
It is the ability to hold the stored bits.
The range of storage permanence
Essentially never losses bits. E.g. mask-programmed ROM
Hold bits days, months, or years after memory's power source turned off. E.g. NVRAM
Holds bits as long as power supplied to memory. E.g. SRAM
Begins to lose bits almost immediately after written. E.g. DRAM
Holds bits after power is no longer supplied.
High end and middle range of storage permanence.