• 1964

Hardware Description

The 1108 was introduced in 1964. Integrated circuits replaced the thin film memory that the UNIVAC 1107 used for register storage. Smaller and faster cores, compared to the 1107, were used for main memory. In addition to faster components, two significant design improvements were incorporated: base registers and additional hardware instructions. The two 18-bit base registers (one for instruction storage and one for data storage) permitted dynamic relocation: as a program got swapped in and out of main memory, its instructions and data could be placed anywhere each time it got reloaded. To support multiprogramming, the 1108 had memory protection using two base and limit registers, with 512-word resolution. One was called the I-bank or instruction bank, and the other the D-bank or data bank. If the I-bank and D-bank of a program were put into different physical banks of memory, a 1/2 microsecond advantage accrued, called "alternate bank timing."