ICL 2900 Series - Implementations

Implementations

The first machines announced in the 2900 Series were the 2980 and 2970. The 2980 allowed one or two order code processors (OCPs), each operating at up to 3 million instructions per second, with real memory configurable up to 8 megabytes, with a 500 nanosecond access time.

The 2980 was initially the most powerful of ICL's New Range mainframe computers. In addition to the OCPs, it consisted of a store multiple access controller (SMAC) and one or more store access controllers (SAC), a general peripheral controller (GPC), one or more disc file controllers (DFC) and a communications link controller (CLC), together with disc drives (a typical configuration would have eight EDS 200 drives), tape decks, an operating station (OPER), line printers and card readers. It supported the VME/B, VME/K and Edinburgh Multiple Access System (EMAS) operating systems. A typical 2980 configuration would cost about £2 million.

Unlike the 2980, the 2970 and the subsequent 2960 were microcoded, and thus allowed emulation of instruction sets such as that of the older 1900 Series or the System 4.

A 2900 Series machine was constructed from a number of functional modules, each contained in a separate cabinet. Peripheral devices were connected using ICL's Primitive Interface (Socket/Plug and cable set) to a Port Adapter on the SMAC. Logical addressing was employed and used a group scheme to identify system components in terms of Ports, Trunks and Streams.

A Trunk was a generic name and a hardware address within a Port to which a peripheral controller would be assigned . A Trunk was a generic name for a controller for a number of Stream devices.A Stream was the generic name for the channel under which individual peripheral devices could be referenced.

The boot process for the 2960 Series is worthy of a special mention: the OCP contained a mini OPER terminal and a cassette deck. At boot, the OCP would perform its Initial Program Load (IPL) from the nominated IPL device . The IPL code provided the means for the OCP to discover the system's hardware configuration, by enquiring down the Stream(s), Trunk(s) and Port(s) to find the default or manually elected boot device for the microcode set and/or Operating System to be booted. This process was called a GROPE or General Reconnaissance Of Peripheral Equipment. The cassette load method also allowed engineering staff to load and execute diagnostic software.