SCSI1

SCSI1 refers to the original standard for the Small Computer System Interface, first introduced in 1986. SCSI is a set of parallel interface standards used for connecting and transferring data between computers and peripheral devices. SCSI1 was designed to be a more robust and higher-performance alternative to the older ST-506 interface commonly used for hard drives in the early days of personal computing.

The SCSI1 standard defined a bus architecture that allowed for multiple devices, up to eight, to be connected to a single host adapter. Devices could be daisy-chained together using SCSI cables. It supported data transfer rates of up to 5 megabytes per second (MB/s) in synchronous mode, and 4 MB/s in asynchronous mode. The interface used a 50-pin connector and supported a maximum cable length of 6 meters.

Key features of SCSI1 included its ability to perform command queuing, allowing a host to send multiple commands to a device without waiting for each to complete before sending the next. This asynchronous operation and command queuing contributed to its perceived performance advantages over other interfaces of the time. While SCSI1 itself is now considered obsolete, it laid the groundwork for subsequent SCSI standards like SCSI-2, SCSI-3, and later, Serial Attached SCSI (SAS), which continued to evolve and improve upon its core principles.