PROMs are basically the same as mask ROMs, once they have been programmed.

More Questions from Memory and Storage

• Once a PROM is programmed it can be changed by applying a small electrical charge.
• DRAM chips can be combined for larger capacity and word sizes using the same methods as for other memory types.
• A nibble is a group of eight bits.
• When a computer is executing a program of instructions, the CPU continually fetches information from those locations in memory that contain (1) the program codes representing the operations to be performed and (2) the data to be operated upon.
• DRAM uses a cross-transistor configuration.
• When two or more devices try to send their own digital levels to a shared data bus at the same time, bus contention will take place.
• A typical RAM will write (store data internally) whenever the Chip Select line is active and the Write Enable line is inactive.
• RAM is nonvolatile.
• Dynamic memories, such as the 2118 16K × 1 RAM, have to multiplex the address bus.
• The time from the beginning of a read cycle to the point when the data output is valid is called propagation delay.

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