Mainframe - I/O channels (separate processor), expensive, physically large, enough memory, flexibility, I/O facilities, and processing speed to meet the needs of large customers. (2, 63)

Grosch's Law - a computer system that was twice as big (cost twice as much) got you not twice but four times as much computing power. (2, p177)

Rise of IBM (2, 67ff)

1952 DoJ alleges violation of anti-trust laws in punch card business

1956 Consent Decree, must allow customers to purchase machines at prices comparable to renting

1957 Model 305 Disk Storage, random access, mass storage (5M chars).
- major advance beyond drum storage
- physically more complex
- renamed RAMAC Memory Accounting Machine (See Magnetic Disks.)
- still using tubes

1959 Oct, Announces Model 1401
- transistors
- core memory
- 1403 chain printer, 600 lines/minute (407 accounting machine, 150 lines/minute)
- projects sale of 1,000 units, sold 12,000

1960, IBM dominates the market
- producing seven different models
- each with its own sales force and software
- becoming a federation of small companies

Mainframe machines

- Keypunch - 026, 029
- IBM 407 Accounting Machine

- For example, Model 7090
- Batch processing

- Model 1401 for tape preparation

- operated by "computation centers"

1962 Jan, decision for a new product family, System/360

1963 Honeywell announces its IBM compatible Model 200

1964 Apr, IBM announces System/360 line

OS 360 - Fred Brooks, The Mythical Man-Month (3)
A software development classic

1. Martin Campbell-Kelly and William Aspray. Computer: A History of the Information Machine (Basic Books, 1996).

2. Paul E. Ceruzzi. A History of Modern Computing (MIT Press, 2000).

3. Frederick P. Brooks, Jr. The Mythical Man-Month  (Addison-Wesley, 1982).