II, TRS-80, and Commodore PET during the home computer boom of 1977, the vast majority of microcomputers came with keyboards and connections for TV screens or other monitors. Common usage An operator would use the front panel to bootstrap the computer, to debug running programs, and to find hardware faults. Storage alteration and display Many computers had controls, e.g., buttons, dials, keyboards, toggle switches, for entering addresses, controls for displaying the data at an address and controls for altering storage contents. These were typically used for booting and debugging. Booting Typically, the operator would have a written procedure containing a short series of bootstrap instructions to be hand-entered using, e.g., dials, keyboard, toggle switches. First, the operator would, e.g., press the address switch and enter the address. For easier entry and readout, on some computers (such as the DEC PDP-8 or MITS Altair 8800) binary digits were grouped into threes or fours on the front panel, with each group of lights or switches representing a single octal (between 0 and 7) or hexadecimal (between 0 and F) digit. Some decimal computers, e.g., IBM 1620, used binary-coded decimal for memory addresses. Next the operator would enter the value intended for that address. After entering several of these instructions (some computers had a deposit next button, which would deposit subsequent values in subsequent addresses, relieving the operator of needing to enter subsequent addresses), the operator would then set the starting address of the bootstrap program and press the run switch to begin the execution of the program. The bootstrap program usually read a somewhat longer program from punched paper-tape, punched cards, magnetic tape, drum or disk which in turn would load the operating system from disk. Some machines accelerated the bootstrap process by allowing the operator to set the controls to contain one or two machine language instructions and then directly executing those instructions. Other machines allowed I/O devices to be explicitly commanded from the front panel (for example, "Read-In Preset" on the PDP-10 or the accessing of memory-mapped I/O devices on a PDP-11). Some machines also contained various bootstrap programs in ROM and all that was required to boot the system was to start it executing at the address of the correct ROM program. Debugging Front panels were often used to debug programs when operating support was limited and most programs were run in stand-alone mode. Typically a front-panel switch could