IBM System/7  The IBM System/7 was a computer system, designed in Boca Raton, Florida, and delivered in 1971. It was a 16-bit machine and one of the first made by IBM to use novel semiconductor memory, instead of magnetic core memory conventional at that date. IBM had earlier products in industrial control market, notably the IBM 1800 which appeared in 1964. However, there was minimal resemblance in architecture or software between the 1800 series and the System/7. The processor designation for the system was IBM 5010. There were 8 registers which were mostly general purpose (capable of being used equally in instructions) although R0 had some extra capabilities for indexed memory access or system I/O. Later models may have been faster, but the versions existing in 1973 had register to register operation times of 400 ns, memory read operations at 800 ns, memory write operations at 1.2 µs, and direct IO operations were generally 2.2 μs. The instruction set would be familiar to a modern RISC programmer, with the emphasis on register operations and few memory operations or fancy addressing modes. For example, the multiply and divide instructions were done in software and needed to be specifically built into the operating system to be used. The machine was physically compact for its day, designed around chassis/gate configurations shared with other IBM machines such as the 3705 communications controller, and a typical configuration would take up one or two racks about high, the smallest System/7's were only about high. The usual console device was a Teletype Model 33 ASR (designated as the IBM 5028), which was also how the machine would generally read its boot loader sequence. Since the semiconductor memory emptied when it lost power (in those days, losing memory when you switched off the power was regarded as a novelty) and the S/7 didn't have ROM, the machine had minimal capabilities at startup. It typically would read a tiny bootloader from the Teletype, and then that program would in turn read in the full program from another computer or from a high speed paper tape reader, or from an RPQ interface to a tape cassette player. Although many of the external devices used on the system used the ASCII character set, the internal operation of the system used the EBCDIC character set which IBM used on most systems. There were various specializations for process control. The CPU had 4 banks of registers each of different priority and it could respond to interrupts within one instruction cycle by switching to the higher priority set.