Starlink from 1984

In May 1984, Digital Research Inc (DRI) announced a product called StarLink 1. It was described as a “hardware/software combination to expand the IBM PC into a multiuser system” 2. The hardware portion was a board containing an Intel 8088 CPU, 64KB of RAM and four RS-232 interfaces for connecting dumb terminals. The software portion was DRI’s Concurrent DOS 3 running on the host PC. Such “multiuser system” could serve up to five users simultaneously - one working at the PC itself, and four via terminals.

DRI Micronotes, First Quarter 1984

The basic idea was to use the multitasking capabilities of Concurrent DOS and replace multiple personal computers with one powerful machine and several “dumb” and hopefully inexpensive terminals.

Digital Research News, October 1984

DRI had supported this model for a while. Its MP/M operating system introduced in 1979, was designed specifically for multiuser 8‑bit computers, and Concurrent DOS was the latest evolution of that technology on the Intel 8086 architecture. So why was additional hardware needed in the first place?

MP/M ran on machines built for multiple users. One example was the 8-bit Altos ACS8000-12A, released in 1981. It had all necessary hardware to support multiple users, including six serial ports, four of which could be used to connect terminals. Later models, such as Altos 586 used the Intel 8086 and could run MP/M-86 or Microsoft XENIX. They were not compatible with IBM PC but, like their predecessors, they provided built-in hardware support for multiple users.

The IBM PC and XT were designed to be single user personal computers. Turning them into multiuser servers required additional hardware. StarLink came with the board that contained the necessary serial ports, and also an additional CPU and RAM to boost the performance of the system. Without StarLink, a PC running Concurrent DOS could still support terminals connected to its two standard COM ports, but StarLink increased the number to four, plus the…