Advanced Communications Riser
The Advanced Communications Riser ( ACR for short ) is a bus system on the PC . The spelling varies depending on the source: partly with and partly the "s" at the end of "Communication".
The bus system is a combination between the Audio Modem Riser (AMR) and the Communication and Networking Riser (CNR). An ACR slot looks like a PCI bus rotated by 180 degrees . Since the ACR bus is downward compatible, AMR cards can also be operated with it. Not all of the 120 pin connectors are needed.
The bus was mainly used in the early 2000s on some mainboards to e.g. B. to connect special audio cards. However, it never really caught on and is rarely used in today's PCs.