This post explains for the Add-Only Memory.

The Part Number is DS2501.

The function of this semiconductor is UniqueWare Add only memory.

The package is TO-92 Type

Manufacturer: Dallas Semiconductor ( Maxim )

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Description

The DS2501 512-bit add-only memory identifies and stores relevant information about the product to which it is associated. This lot- or product-specific information can be accessed with minimal interface-for example, a single port pin of a microcontroller. The DS2501 consists of a factory-lasered registration number that includes a unique 48-bit serial number, an 8-bit CRC, and an 8-bit family code (11h) plus 512 bits of EPROM that is user-programmable.

It is a 512Kb add-only memory, often referred to as a 1-Wire EEPROM (Electrically Erasable Programmable Read-Only Memory). The 1-Wire protocol is a communication protocol developed by Dallas Semiconductor (now a part of Maxim Integrated) that allows for communication with devices over a single data line.

Data is transferred serially via the 1-Wire protocol which requires only a single data lead and a ground return. The entire device can be programmed and then write-protected if desired. Alternatively, the part may be programmed multiple times with new data being appended to, but not overwriting, existing data with each subsequent programming of the device.[…]

Features:

. 512 bits Electrically Programmable Read Only Memory (EPROM) communicates with the economy of one signal plus ground

. Unique, factory-lasered and tested 64-bit registration number (8-bit family code + 48-bit serial number + 8-bit CRC tester) assures absolute traceability because no two parts are alike

. Built-in multidrop controller ensures compatibility with other MicroLAN products

. EPROM partitioned into two 256-bit pages for randomly accessing packetized data

. Each memory page can be permanently write-protected to prevent tampering

. Device is an “add-only” memory where additional data can be programmed into EPROM without disturbing existing data

. Architecture allows software to patch data by superseding an old page in favor of a newly programmed page

. Reduces control, address, data, power, and programming signals to a single data pin

. Directly connects to a single port pin of a microprocessor and communicates at up to 16.3 kbps

. 8-bit family code specifies DS2501 communications requirements to reader

Download DS2501 Datasheet