I. Read Commands

A. Buffer Reads:

️· Purpose: Read data directly from the SRAM data buffer (264 bytes or 256 bytes).
️· Opcode Options & Characteristics:
- D4H: Can be used at any SCK frequency up to f CAR1.
- D1H: For lower frequency read operations, up to f CAR2.
️· Address Bytes: Comprised of don't care bits and buffer address bits (BFA8-BFA0 or BFA7-BFA0). One don't care byte is also needed after address bytes for initialization.
️· Wrap-Around: Reading continues back to the beginning of the buffer when the end is reached.

B. Main Memory Page Reads:

️· Purpose: Read data from a specific page in the main memory array.
️· Commands & Characteristics:
- Page Erase Command (81H): Required to erase pages before programming them.
■ Requires address bytes composed of don't care bits and page address bits (PA9-PA0 or A17-A8).
- Main Memory Page Read (Implied by other commands): Data is read when programming using the Buffer to Main Memory Page Program with/without Built-in Erase commands.
️· Wrap-Around: When reading continues from the end of the page back to the beginning.

C. Read Commands Summary Table

Command Type	Opcode	Buffer Size	Don't Care Bits	Buffer Address Bits	Key Characteristics
Buffer Read (Any SCK)	D4H	264 bytes/256 bytes	Varies	BFA8-BFA0/BFA7-BFA0	Higher speed
Buffer Read (Lower SCK)	D1H	264 bytes/256 bytes	Varies	BFA8-BFA0/BFA7-BFA0	Lower speed
Main Memory Page Read (Implied)	N/A	N/A	N/A	N/A	Happens during programming, page wrap
Page Erase	81H	N/A	Varies	PA9-PA0 or A17-A8	Required before programming pages

Important Notes:

️· Don't Care Bits: The number and placement of don't care bits vary depending on the command and buffer/page size. Consult the table within the datasheet.
️· Speed Limitations: The choice of opcode (D4H vs. D1H) significantly impacts the read speed.
️· Wrap-Around: Understanding the wrap-around behavior is important for sequential data transfers.