IBM System/370 Model 135 explained
| IBM System/370 Model 135 |
|
| Manufacturer: | International Business Machines Corporation (IBM) |
| Family: | System/370 |
| Discontinued: | October 16, 1979 |
| Website: | IBM Archives |
The IBM System/370 Model 135 was announced March 8, 1971,[1] the only 370 introduced that year. The 135 was IBM's fifth System 370, and it was withdrawn October 16, 1979.
Special features
Although microcode was not a uniquely new feature at the time of the 135's introduction, having been used in most System/360 models and in most System/370 models introduced so far, the ability to upgrade a system's microcode without changing hardware, by storing the microcode in read-write memory rather than read-only memory, was not common at that time.[2] [3]
The read-write memory containing the firmware was loaded from a "reading device located in the Model 135 console"; this allowed updates and adding features to the Model 135's microcode.[1] The "reading device" was a built-in (read-only) floppy disk drive.[4] The 145, introduced the prior year, also had this feature.[5]
Optional features
The Model 135 was the last of the 370s to be introduced without Virtual memory. Four of the five could be upgraded. Unlike the 155 & 165, which required an expensivehardware upgrade to add a DAT box (Dynamic Address Translation), the 135 & 145 [6] could obtain their virtual memory upgrades from a floppy disk.
Microcode upgrades were also available to add "user-selected options such as
An upgraded Model 135[7] was termed a 370/135-3
Customers of the 370/135 had a choice of four main memory sizes, ranging from 96K to 256K.
Other
- The 370/135 was introduced as running "under either OS or DOS.[1] Newer versions thereof (DOS/VS and OS/VS1) and Virtual Machine Facility/370 (VM/370) subsequently became available options once the 135's microcode was upgraded to support virtual memory. This was priced at $120,000 and came with "increased reloadable control store in addition to some power units." The upgrade could be done "in the field" and the resultant system was now deemed a 370/135-3.[8]
- The 135 was "partly developed at Hursley, UK."[9]
Images
See also
External links
Notes and References
- Web site: System/370 Model 135. IBM Archives. 23 January 2003 . IBM.
- A. . Padegs . September 1981 . System/360 and Beyond . IBM Journal of Research & Development . IBM . 25 . 5 . 377–390 . 10.1147/rd.255.0377 . In the initial System/360 models, microprograms resided in read-only storage, but in most later models read-write storage is used.. - tables include model characteristics (Table 1) and announcement/shipment dates (Table 2). The S/370-155-II and -165-II are listed under the former but not the latter, because the upgraded systems were not formally announced as separate models. The "System/370 Advanced Function" announcement, including the -158 and -168, was the main public event.
- DOS/360: Forty years . May 16, 2005 . alt.folklore.computers . No, you'll find no IMPL button on a System/360 Model 30. control store was Card Capacitive ROS. System/360's used a variety of read only control stores, so changing the microcode meant replacing parts (e.g., with parts that were personalized by punching holes in a card). Later models like the 85 and 25 had writable control stores, the 85 using a volatile SRAM array and the 25 using a part of core memory.. 2023-10-02.
- Web site: Floppy Disks - CHM Revolution. 2021-06-09. www.computerhistory.org.
- http://www.computerhistory.org/timeline/1968/#169ebbe2ad45559efbc6eb357200edaf describes it as an 80K 8-inch floppy.
- Book: IBM Maintenance Library 3145 Processing Unit Theory - Maintenance. SY24-3581-4. Fifth. IBM. CPU 139.
- Book: Computerworld . 1976-07-05 . IDG Enterprise . en.
- Web site: Users May Have Jump on Upgrades. July 5, 1976. Computerworld. 2.
- Web site: Some Key Dates in IBM's Operations in Europe, the Middle East, Asia. IBM.
