4.6 2.1.2. solid state era  (Page 3/11)

“The Legendary IBM 1401 Data Processing System” by Robert Garner and Fredrick (Rick) Dill, IEEE Solid State Circuits Magazine , Winter 2010, Vol.2, No.1, pp.28-39.

It was an all transistor Main Frame Computer. Using Automatic Logic Design Software, the volume and power were reduced by 50% and 90% respectively. Standard Modular System of packaging was used which made it compact. The Logic Family used was Saturated-Transistor-Transistor-Logic (TTL-74 Series). The clock rate was 250kHz. Compare this with todays eight core system which has a clock rate of 3GHz in 2013. Memor-to-Memory Architecture was used This reduced the number of instructions needed for acconting and business programs. IBM 1401 had a entry level rental price at US $2500 per month as compared to the previous rental price of $40,000 per month. This economy in rental allowed IBM to capture 50% of Office Computerization.

Full size system had 500,000 discrete components, weighed 4 tonnes, consumed 13,000W, used 10,600Ge-alloy-junction BJT, used 13,200Ge-point contact diodes, it had 16kBytes memory space and it clocked 87kHz.

In 50 machine cycles i.e.. in 0.5ms the computer could add 2 positive 20-digit numbers. Today Pentium IV with a clock rate of 2.5GHz requires only 20ns. 50 machine cycles*(1/Clk_Rate)= addition time of 2 positive 20 digit numbers.

Using the above formula we get the computation time. Clock rate of 87kHz corresponds to 11.5μs Machine Cycle time. Hence 50 machine cycles will take 0.57ms.

If we assume a Clock Rate of 2.5GHz then we have a Machine Cycle Time equal to 0.4ns. So a addition which takes 50 Machine Cycles will take a computation time of 20ns.

Magnetic Core-Memories were not solid state hence they were bulky and 300 million times more costly tham DRAM. The speed and print quality was very good hence IBM 1401 became the Industry’s work-horse. It contributed to the growth of programming as a profession and to the growth of software as an Industry. Use of IBM 1401 in offices created a huge demand of Programmers as well as Software Engineers. But it had a problem with standardization and compatibility. Hence by 1964, IBM 1401 was completely replacxed by S/360 which was compatible and scalable computer family.

2.1.2.2. Mini-Computer Era .

In 1960, Digital Equipment Corporation(DEC) introduced PDP-1(Programmable Data Processor). It was Cabinet Size Office Computer at a total cost of $120,000.00. It was all-transistor System with magnetic-core-memory. Cloak Rate was 200kHz hence Machinew Cycle Time was 5μs. It performed at 100,000 Operations Per Second(OPS).

One operation or instruction took 2 machine cycles hence it took 10μs. Therefore number of Operations Per Second = 1/10μs = 100,000 OPS.

This was the first computer which introduced the concept of user interactive. It created hacker’s culture at MIT. It allowed a game ‘SpaceWar’ to be played.

By 1961, first RTL digital IC chip was commercialized and in 1964 firstr analog IC Chip MC1530 (Operational Amplifier) was commercialized.