HP-150 (aka HP Touchscreen or HP 45611A) was a compact, powerful and innovative computer made by Hewlett-Packard in 1983. It was based on the Intel 8088 CPU and was one of the world's earliest commercialized touch screen computers. Like other "workalike" IBM PC clones of the time, despite running customized MS-DOS versions 2.01, 2.11 and 3.20, the machine was not IBM PC DOS compatible. Its 8088 CPU, rated at 8 MHz, was faster than the 4.77 MHz CPUs used by the IBM PC of that period. Using add-on cards, main memory could be increased from 256 KB to 640 KB. However, its mainboard did not have a slot for the optional Intel 8087 math coprocessor due to space constraints. An HP-150 with an optional hard disk was called HP Touchscreen MAX. The computer's screen was a 9-inch Sony CRT surrounded by infrared emitters and detectors which detected the position of any non-transparent object that touched the screen. In the original HP-150, these emitters and detectors were placed within small holes located on the inside of the monitor's bezel (which resulted in the bottom series of holes sometimes filling with dust, causing the touchscreen to fail until the dust was vacuumed from the holes). Like the original Macintosh, HP-150 was packaged with the CRT display as a single unit, and made use of 3½-inch floppy disks. Unlike the Mac, however, HP-150 had no internal floppy drive; the machine sat atop the phone book-sized 9121D dual 3½-inch floppy (76 mm high, 325 mm wide, 285 mm deep) or similarly sized hard disk devices, connected by HP-IB. Invisible to the user, the HP 150 runs "Terminal Operating System" ("TOS", code-named "Magic" during development). This operating system generally runs only two tasks: the terminal emulator and MST (which is Microsoft DOS). Hardware Display Display resolutions: Text: 80 columns × 27 lines (720 × 378 pixels) Character size: 7 × 10 pixels Character cell size: 9 × 14 pixels Inherent HP Terminal emulation equivalent to HP 2623 Graphics Terminal Bit-map: 512 × 390 pixels Separate plane for text and graphics Monitor sensor grid: 40 (h) × 24 (v) HP-150's touch screen sensor grid is quite coarse. Its resolution is only two characters wide. Used mainly for rough cursor positioning and function key control, it could not be used to draw pictures. Processor unit Optional internal thermal printer HP 2647A (fax roll) Communication ports: Two RS-232