Read-only memory (ROM) is a type of non-volatile memory used in computers and other electronic devices. Data stored in ROM cannot be electronically modified after the manufacture of the memory device. Read-only memory is useful for storing software that is rarely changed during the life of the system, sometimes known as firmware. Software applications for programmable devices can be distributed as plug-in cartridges containing read-only memory. Strictly, read-only memory refers to memory that is hard-wired, such as diode matrix or a mask ROM integrated circuit, which cannot be electronically changed after manufacture. Although discrete circuits can be altered in principle, integrated circuits (ICs) cannot. Correction of errors, or updates to the software, require new devices to be manufactured and to replace the installed device. Erasable programmable read-only memory (EPROM) and electrically erasable programmable read-only memory (EEPROM) can be erased and re-programmed, but usually this can only be done at relatively slow speeds, may require special equipment to achieve, and is typically only possible a certain number of times.
“This article presents an very original computer. Its CPU is only made of ROM, but it can execute complex programs, such as finding all the solutions of the 8-queens problem. Since the 1970s, computers are essentially composed of microprocessors, memory …