Attached Support Processor

Attached Support Processor (ASP) was an implementation of loosely coupled multiprocessing for IBM's OS/360 operating system.

ASP was introduced in March 1967, and initially allowed connection of two System/360 computers via a channel-to-channel adapter (CTCA).

[3] As initially defined an ASP system typically[a] consisted of a large System/360 computer, a Model 50, 65, or 75 running OS/360, called the main processor, and a smaller System/360, Model 40 or larger, called the support processor, running the ASP supervisor as a single task under OS/360 PCP (Primary Control Program).

The support processor was a minimum of a Model 40 G (G indicates memory size of 128KB) with two selector channels, a 1052 console typewriter, a 2540 card read/punch, a 1403 printer, and three 2311 disk drives.

With the introduction of MVS for System/370 IBM rewrote and renamed ASP as Job Entry Subsystem 3 (JES3) and it is still in use as of 2015.