ATM25

In the early years of ATM, there was an initiative by IBM and some partner companies such as Madge for an ATM standard with lower transmission rates: ATM25.

This ATM concept was to be used primarily in the local area. This initiative aimed at a data rate of 25 Mbit/s and was therefore called ATM25.

ATM25 was standardized by the ATM Forum and specified the transmission of ATM cells at 25.6 Mbps. The advantage of ATM25 at that time was mainly the availability of inexpensive chipsets. ATM25 used 4B5B coding for the transmission of the bit stream, whereby the cell transmission was basically asynchronous. The synchronization was transmitted within a time frame.