IBM System/370 Model 168
| Company type | Computer system |
|---|---|
| Industry | Mainframe computers |
| Predecessor | IBM System/370 earlier models without virtual storage |
| Founded | August 2, 1972 |
| Defunct | September 15, 1980 |
| Headquarters | Armonk , United States |
| Products | Mainframe computer |
The IBM System/370 Model 168 alongside the Model 158 were both unveiled on August 2, 1972. Earlier System/370 versions did not incorporate virtual storage, a feature that became central to the 370 series; consequently, the 168 and 158 are frequently regarded as the first truly representative "real 370" systems. In 1972, the System/370 Advanced Function introduced new Address Relocation Hardware and added support for four new operating systems: VM/370, DOS/VS, OS/VS1, and OS/VS2.
Both the 158 and 168 models were retired from production on September 15, 1980.
Main memory
The main memory was organized with four-way doubleword interleaving and could be configured from 1 up to 8 megabytes in increments of one megabyte.
Unlike the earlier IBM System/370 Model 165, which utilized magnetic-core memory and debuted two years earlier, the Model 168 employed semiconductor memory technology, resulting in enhanced speed and a more compact physical footprint.
System console
The IBM 3066 Model 2 System console, similar to the Model 1 console of the 165, replaced most switches, pushbuttons, and indicators, retaining only a select few such as "system clear" and "cooling reset alarm." It also featured a microfiche document reader, a capability initially introduced with the IBM System/360 Model 85 console.
An optional console printer capable of printing up to 85 characters per second was available for producing hard copies in display mode and was mandatory when operating in printer-keyboard mode.
Disk storage
The IBM 3330 Model 11 disk drive offered removable disk packs and doubled the storage capacity compared to earlier 100 MB models by increasing the number of data cylinders while keeping the platter count unchanged. However, it was not compatible with the System/370 Model 165.
Multiprocessing
Multiprocessing (MP) variants were available for both the 370/168 and 370/158, featuring tightly coupled multiprocessing architectures. The Model 168 supported two multiprocessing configurations: tightly coupled MP and connection of a secondary IBM 3062 Attached Processing Unit, which did not have direct access to Input/Output channels.
Extended precision floating-point
Support for extended precision floating-point operations using 128-bit hexadecimal operands was standard across all Model 165 and Model 168 units, while it was offered as an optional no-cost feature on the System/370 Model 158.
Emulation
An optional IBM 7070/7074 Compatibility Feature allowed the Model 168 to execute IBM 7070 and 7074 software at speeds matching or exceeding those of the original machines without disrupting standard System/370 functions. Additional compatibility options extended support to IBM 7080 and IBM 709/7090/7094 II systems; however, these compatibility features could not be enabled simultaneously.
System/370 Extended Facility
The optional Extended Facility on the Model 168-3 improved support for MVS/System Extensions (MVS/SE) and MVS/System Product (MVS/SP), enhancing both functionality and performance of the MVS operating system on compatible System/370 hardware.
168-1 & 168-3
IBM's June 1975 edition of the 168 Guide introduced the Model 168-3 variant, identifying two versions within the Model 168 line: Model 1 and Model 3.
In comparison to the then-new IBM 3033, IBM referred to the System/370 Model 168-3 as "the company's previous flagship."
The CPU of the Model 168-3 delivered internal performance improvements ranging from five to thirteen percent over that of the Model 168-1.