Introduction
Control Data Corporation produced the CDC 3000 series, which consisted of CDC 3600 and CDC 3100 computers, in the middle of the 1960s as an upgrade to the CDC 1604 and CDC 924 systems. A variety of machines were created over time and were categorised into the higher 3000 series in 48-bit and the lower 24-bit 3000 series. Magnetic-core memory was utilised by all 3000 series computers. The CDC 3500 computer utilised the same core memory modules as the CDC 6000 computer.
The Control Data 3000 series, which had been the company’s cash cows during the 1960s and had allowed it to operate while the 6000 series was being developed, was phased out of production by CDC in the early 1970s. Magnetic-core memory was utilised by all 3000 series computers. The CDC 3500 computer utilised the same core memory modules as the CDC 6000 computer.
3000 upper Series
The word size for the higher 3000 series was 48 bits. The CDC 3600, which was originally delivered in June 1963, was the first 3000 machine to be manufactured. The CDC 3400 and CDC 3800 made their first deliveries in December 1965. These devices, which served as the upgrade option for CDC 1604 customers, were created specifically for use in scientific computing applications. However, when the CDC 6600 was shown in December 1964 and shipped in January 1965, these computers were eclipsed by the impending 60-bit CDC 6000 series machines. Some high-end computer laboratories bought these computers as a band aid while they awaited the arrival of their 6600 machine.
3000 Lower Series
The word size for the lower 3000 series was 24 bits. The CDC 924, a 24-bit variant of the 48-bit CDC 1604, served as their foundation. The CDC 3200 was the first lower 3000 model to be made available, and it was followed by the smaller CDC 3100, built in February 1965, and the CDC 3300, built in December 1965. The CDC 3500, the last device in the line, was introduced in March 1967 and employed integrated circuits as opposed to discrete components. The BDP (Business + Data Processing) instructions, floating-point arithmetic, and optional relocation capabilities were available on the 3300 and 3500. These devices were made with business and commercial computing in mind.
Software
SCOPE was the name of the operating system for the top 3000 (Supervisory Control Of Program Execution). Tape SCOPE was a serial batch operating system that lacked print spooling or card reading buffers. Drum SCOPE offered print spooling and improved performance. To take advantage of the hardware’s extensive characteristics, CDC created an operating system for the 3800 dubbed SUMMIT (Simultaneous Usage of Multiprogramming, Multiprocessing with Interactive Timesharing). The Summit was never made public because CDC devoted all of its efforts to developing the 6600 system.
Architecture
The lower 3000 CPU had a 24-bit architecture, with the two operand registers A and Q and instructions each having a length of 24 bits. B0 through B3 are the four 15-bit index registers, although B0 is always zero. There was no status register, flags, or condition codes. Core memory may include up to 32,768 words at 24 bits per word and be swapped between different banks. The most prevalent memory bank combinations were two or three.
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