NOR Flash

Contents [hide]

• Flow chart of order of operations
• Troubleshooting/tips and tricks
• Related Topics
• Further reading

Background information

NOR flash is completely different to NAND in the fact that it uses NOR gates instead of NOT and AND gates like NAND does.

Difference in NOR and NAND

• NOR has a faster read speed, where as NAND has a faster write and erase speed.
• NOR is more expensive
• NAND has a higher capacity than NOR
• NOR can be run in parallel and in series, Whereas NAND runs in series meaning it can wire 8 bits of data at once e.g. one byte at a time(8 bits = 1 byte)
• When NOR is run in parallel it allows for one-byte random access which means instructions can be taken and run directly from the chip simple to how RAM functions
  hence why NOR has uses a static random-access memory(SRAM)interface that includes an address pins to map to every part of the chip, which allows access to every byte stored on the chip.
  However, this means that NOR has to write in larger chunks than NAND, which ultimately reduces the speed of the chip and its lifetime as a larger area is worn through use.
• NOR is typically used for tasks such as code execution due to its SRAM function, however this does make it more expensive to produce (per bit) whereas NAND lacks SRAM so is typically used for data storage
• Initially, NOR requires a higher power draw upon start up but requires less power during operation than NAND typically would.
• NOR is typically used to storage an embedded device firmware due to its higher read performance when compared with NAND

Serial NOR and Parallel NOR

Serial NOR

Serial NOR typically communicates over a serial protocol(3 to 4 wires) whereas Parallel uses one wire for every part of the chip
This means that Serial transfer one bit at a time whereas Parallel can transmit multiple bits at once(8 wires, means at bits/one byte at once).
Due to the simpler connection scheme, serial NOR is typically cheaper and simpler to produce as well as saving space on the PCB where there isn't much space
It also tends to draw less power than Parallel, all these factors considered makes it a good candidate for small low powered devices, such as IOT and mobile devices.

Differences between Serial and Parallel

• Serial processes one bit at a time where as parallel process multiple bits at the same time
• Serial is slower because of the singular bit processing, whereas parallel is faster due to its multiple bit processes
• Serial is cheaper and less complex due to only needing a 3/4 wire serial interface, whereas parallel is more expensive and more complex due to it needing an address pin for every area of a chip
• Serial is typically used for in low power system were power management is critical and communication systems as well as shift registers, whereas parallel NOR is used for high speed functions, such as
  device booting or pattern matching due to the fact it can move bits in parallel

Flow chart of order of operations

Insert a flow chart of steps and actions for each task (create using diagram)

Troubleshooting/tips and tricks

Fixes to any common issues that were encountered or could be easily encountered

Related Topics

Topics such as desoldering to chip off or firmware dumping for disk PCB repairs

• NAND flash

Further reading

External references in wiki references can just be cited through the keyword link

1. Reference 1: Definition of NOR flash memory
2. Reference 2: What is Serial NOR Flash Memory?