While early IBM PCs had single color green screens, these screens were not terminals. The "screen" of a PC did not contain any character generation hardware; all video signals and video formatting were generated by the "video display card" in the PC, or (in most graphics modes) by the CPU and software. An IBM PC monitor, whether it was the green monochrome display or the 16-color display, was technically much more similar to an analog TV set (without a tuner) than to a terminal. With suitable software a PC could, however, emulate a terminal, and in that capacity it could be connected to a mainframe or minicomputer. The Data General One could be booted into terminal emulator mode from its ROM. Eventually microprocessor-based personal computers greatly reduced the market demand for conventional terminals.