Editing RETAIN (section)

=== Remote support ===

At the time System/370 was announced, along with the corresponding RETAIN/370 system, IBM announced that the new family of computers would be equipped to permit remote diagnosis of hardware problems. Each System/370 installation of model 145 and above have a telecommunications adapter included capable of being used for remote support. The hardware diagnostic programs were written to allow control via a remote connection to applications on the RETAIN system that could be controlled by IBM specialists located at the IBM support center in Chicago, managed by Paul Rushton, and also including the original plant of manufacture of the CPU. This form of support was dubbed "Data Link / Hardware".  The connection was made through a communications device called an IBM 2955 adapter, a stripped-down variant of the [[270x|2701 communications controller]]. It could connect at 600 bit/s to the RETAIN system to run diagnostics. Mainly, this was to run mostly the same diagnostics that could be run locally by an IBM CE, but in time other specialized applications were developed, such as programs to analyze "logouts" generated by hardware malfunctions, i.e. "machine check" interruptions.

In time, the concept of remote support was extended to software as well (about 1973 or 1974). Through a special application, an MVS system could be connected, via RETAIN, to an IBM support center, and memory dumps and other system data could be examined remotely. The application also permitted download of software fixes, or [[IBM Program temporary fix]]es. Although the 2955 only supported a 6-bit character code (similar to the 2740 terminal), binary transfer of memory dump and software updates was accomplished through a protocol similar to the base-64 encoding scheme used today on the Internet for email attachments.

Over the years, several projects have aimed to supplant RETAIN's functionality, but it has shown lasting presence despite them.