Final answer:
The error checking technology used by older SIMMs is the parity bit, which helps detect errors in the stored or transmitted data.
Step-by-step explanation:
The error checking technology used by older Single Inline Memory Modules (SIMMs) is the parity bit. The parity bit is an additional bit added to a group of data being stored or transmitted, which is used to check whether the number of set bits (bits with the value 1) is odd or even. This is a simple form of error detection that can indicate the presence of an error. Other technologies like Error Correction Code (ECC), Cyclic Redundancy Check (CRC), and Checksum are used for error detection and correction, but they weren't commonly used in older SIMMs as much as parity was.