EPROM stands for :
Erasable Programmable Read Only Memory
EPROM expands to Erasable Programmable Read Only Memory — option 1. The leading E stands for erasable, not electrically, and that single letter is what the question tests.
The family, in order of increasing convenience :
| Type | Written by | Erased by | Erase granularity |
|---|---|---|---|
| ROM | Mask at manufacture | Not possible | — |
| PROM | User, once (fusible link) | Not possible | — |
| EPROM | User, electrically | Ultraviolet light | Whole chip |
| EEPROM | User, electrically | Electrically | Byte |
| Flash | User, electrically | Electrically | Block / sector |
The quartz window is the giveaway. An EPROM is instantly recognisable by the transparent window over the die: erasure means exposing the chip to short-wave ultraviolet (253.7 nm) for 15 to 20 minutes, which gives the trapped electrons enough energy to leave the floating gate and return every cell to 1. The window is covered with an opaque label in service, because ordinary fluorescent light and sunlight will eventually erase it too.
How a cell works. Each bit is a MOSFET with an extra floating gate buried in the oxide. Programming injects hot electrons onto that gate; the trapped charge raises the transistor's threshold voltage so it no longer turns on at the normal read voltage, storing a 0. With no path for the charge to leak away, retention is measured in decades — which is what makes the memory non-volatile.
Why option 3 is the deliberate distractor. "Electrically Programmable" is true of EPROMs — they are written electrically — but the acronym reserves that meaning for EEPROM, where the second E means electrically erasable. Option 2 fails twice over: these devices are read-mostly, not read-write, and the expansion is simply wrong.
Hence, EPROM stands for Erasable Programmable Read Only Memory.
Similar Questions
Match the following :
List - I List - II (a) 24C01 (i) Parallel EPROM (b) 28C64 (ii) EPROM (c) 74S288 (iii) Serial EEPROMS (d) 27C010 (iv) TTL PROM Codes :
Assertion (A) : Flash memory is non-volatile memory that can be electrically erased and reprogrammed.
Reason (R) : Flash memory is a specific type of EEPROM that is erased and programmed, in-circuit, in large blocks in contrast to EEPROM which is erased and reprogrammed at the byte level.
Select your answer using the codes given below :
Important Questions from Semiconductor Memories
Each cell of a static RAM contains
Which of the following memories can be programmed once by the user and then cannot be erased and reprogrammed?
- How many storage locations are available when a memory device has 12 address lines?
How many bits are in a byte?
Class of mass memory devices that use a laser beam to write and read on to a specified coated disk
