IBM 5151

The IBM 5151 is a 12" transistor–transistor logic (TTL) monochrome monitor, shipped with the original IBM Personal Computer for use with the IBM Monochrome Display Adapter.  A few other cards were designed to work with it, such as the Hercules Graphics Card.

The monitor has an 11.5-inch wide CRT (measured diagonally) with 90 degree deflection, etched to reduce glare, with a resolution of 350 horizontal lines and a 50 Hz refresh rate. It uses TTL digital inputs through a 9-pin D-shell connector, being able to display at least three brightness levels, according to the different pin 6 and 7 signals. It is also plugged into the female AC port on the IBM PC power supply, and thus did not have a power switch of its own.

The IBM 5151 uses the P39 phosphor type, producing a bright green monochrome image intended for displaying high-resolution text. This phosphor has high persistence, which decreases display flicker but causes smearing when the image changes.