What are Microprocessor SIM Cards and Types?

The most important part of a SIM card is its Microcontroller. It is a standard ROM chip chip with a size of between 64 KB and 512 KB. RAM size is between 1KB to 8KB while EEPROM size is between 16KB to 512 KB. The ROM contains an OS or card operating system, while EEPROM contains data called personalization that includes security keys, phone book, SMS settings, etc. The operating voltage of SIM is probably, 1.8V, 3V or 5V but the operating voltage of most modern SIM supports 5V, 3V, and 1.8V.

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There are two types of microprocessor cards. These cards take the form of contact cards, require a card reader, or non-touch cards, using radio signals to operate.

SIM Card Types:

There are two types of SIM cards namely GSM and CDMA:


GSM technology represents the Global System for Mobiles and its foundation could be laid in Bell Laboratories in the 1970s. It uses a switching system and divides each 200 kHz signal into 8 25 kHz intervals and operates in 900 MHz, 800 MHz, and 1.8 MHz GHz bands. It uses a low bandwidth transmission method – basically Time Division Access Multiplexing. Data transfer rates vary from 64kbps to 120kbps.


CDMA refers to multi-code access that explains the communication channel system that uses spread-spectrum technology as well as a special coding system that is a multiplication time division and a frequency division system.

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