The IBM System/370 Model 145 was announced September 23, 1970, three months after the

155 Year 155 ( CLV) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Severus and Rufinus (or, less frequently, year 908 ''Ab urbe condita'' ...

and

165 Year 165 ( CLXV) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Orfitus and Pudens (or, less frequently, year 918 ''Ab urbe condita'' ...

models. It was the fourth member of the

IBM System/370 The IBM System/370 (S/370) is a model range of IBM mainframe computers announced on June 30, 1970, as the successors to the System/360 family. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path f ...

line of computers, and was the first IBM computer to use

semiconductor memory Semiconductor memory is a digital electronic semiconductor device used for digital data storage, such as computer memory. It typically refers to devices in which data is stored within metal–oxide–semiconductor (MOS) memory cells on a sili ...

for its main memory instead of magnetic core memory. It was described as being five times faster than the IBM System/360 Model 40. First shipments were scheduled for late summer of 1971.

New capabilities

The System/370's basic architecture was described as having been an extension, but not a redesign, from that of IBM's 1964-introduced System/360. The 370 introduced some new instructions, such as * MOVE CHARACTER LONG (MVCL) and * COMPARE CHARACTER LONG (CLCL), thereby permitting operations on up to 2²⁴-1 bytes (16 MB), vs. the 256-byte limits on the 360's MVC and CLC, but lacked a DAT (Dynamic Address Translation) box.

Virtual memory

Some said about the early members of the

family, looking back, that they were not "the real 370 line" because "neither offered virtual storage capability, which was to be a hallmark of the 370 line." Unlike the earlier Model 155 and 165 systems, for which an upgrade to virtual memory required the purchase of an expensive upgrade to add a DAT box, the 145's customers had two advantages: * 370/145 customers did not have to wait as long for this lack of virtual memory to be remediedJune 1971 vs. Aug. 1972 * there was no need to buy extra hardware: An upgrade to the 145's

microcode In processor design, microcode (μcode) is a technique that interposes a layer of computer organization between the central processing unit (CPU) hardware and the programmer-visible instruction set architecture of a computer. Microcode is a laye ...

through a new microcode floppy diskIBM Maintenance Library 3145 Processing Unit Theory - Maintenance. IBM. pp. CPU 117–129. SY24-3581-2 enabled virtual memory capability.

VM/CMS

Upon gaining virtual memory capability via a microcode update, the 145 could now support the VMF (Virtual Machine Facility) and VM/CMS, a time-sharing system.

Notes

References

{{DEFAULTSORT:IBM System 370 Model 145 IBM System/360 mainframe line Computer-related introductions in 1970

New capabilities

Virtual memory

VM/CMS

See also

Notes

References