The HP 2640A and other HP 264X models were block-mode "smart" and intelligent ASCII standard serial terminals produced by Hewlett-Packard using the Intel 8008 and 8080 microprocessors.
The HP 2640A was introduced in 1975, and used an Intel 8008 CPU, and was priced at US$3500. At introduction, it could have up to 8 KB of RAM (two 4 KB semiconductor RAM cards). Also introduced in 1975 was the HP 2644A, which was an HP 2640A with mass storage (two mini-tape cartridges), for US$5000.
The HP catalogs usually refer to the terminal model as simply "2640A", and infrequently as "HP 2640", or "HP 2640A" (both with a blank after the "HP"), or "2640". The incorrect "HP2640" and "HP2640A" are often seen outside of HP.
The functionality defined by the HP 264X series hasn't changed much as the preferred terminal for HP1000 and HP 3000 series computers. They never achieved the notoriety of the VT100 among programmers, but included sophisticated features not found in the VT100, such as offline forms, multipages, and (in some models) local storage.
The styling looked like vaguely like a toaster oven. It was boxy, with a "widescreen" aspect ratio. HP had determined that the combination of a standard 4:3 aspect ratio with the 25 line by 80 character display that was the standard of the time required the characters to have a very high profile. HP's response was to specify a CRT with an aspect ratio designed around the desired character shape instead of the other way around. Of course, this also mandated rather high manufacturing costs as standard parts could not be used.
HP took pains to further improve the rendering of displayed characters via half-pixel positioning of individual lines within each character. Although the character cell was only 7 horizontal by 9 vertical dots, half-pixel positioning effectively doubled the horizontal resolution to 14 dots, giving the characters very smooth outlines. (The initial sales literature referred to it as using a 7×9 matrix generated in a 9×15 dot character cell).
All of this resulted in an extremely easy to read display with the dot-matrix nature, and the scan lines, almost invisible.
The keyboard had flat tops, similar to the HP 9800 series desktop computers rather than the curved contours now considered to be ergonomic. It featured three keypad areas: Alphabetic, numeric, and an array of cursor positioning and editing keys somewhat similar to modern PC keyboard layouts. There were also a number of smaller function and feature control keys arrayed in two rows above the normal keypad areas. The keyboard chassis was separate from the main body, connected via a thick cable. The keyboard used a bit-paired layout (similar to that on a teleprinter machine) rather than the typewriter-paired arrangement on DEC's VT100. Although large, users loved the keyboard because "it had a key for everything".