The memory which is programmed at the time it is manufactured
The memory PROM is programmed at the time it is manufactured.
A typical PROM comes with all bits reading as "1". Burning a fuse bit during programming causes the bit to read as "0". The memory can be programmed just once after manufacturing by "blowing" the fuses, which is an irreversible process.
Short for programmable read-only memory, a memory chip on which data can be written only once. ... To write data onto a PROM chip, you need a special device called a PROM programmer or PROM burner. The process of programming a PROM is sometimes called burningthe PROM.
Proms are commonly known as JS prom, or, junior–senior prom. Conversely, if a high school has separate dances for juniors and seniors, the term "prom" is reserved for the juniors, and the dance for the seniors is called a "graduation ball" (often abbreviated as "grad ball" or simply "ball".)