ROM in the context of Diode matrix

Very-large-scale integration (VLSI) is the process of creating an integrated circuit (IC) by combining millions or billions of MOS transistors onto a single chip. VLSI began in the 1970s when MOS integrated circuit (metal oxide semiconductor) chips were developed and then widely adopted, enabling complex semiconductor and telecommunications technologies. Microprocessors and memory chips are VLSI devices.

Before the introduction of VLSI technology, most ICs had a limited set of functions they could perform. An electronic circuit might consist of a CPU, ROM, RAM and other glue logic. VLSI enables IC designers to add all of these into one chip.

Integrated circuit design, semiconductor design, chip design or IC design, is a sub-field of electronics engineering, encompassing the particular logic and circuit design techniques required to design integrated circuits (ICs). An IC consists of miniaturized electronic components built into an electrical network on a monolithic semiconductor substrate by photolithography.

IC design can be divided into the broad categories of digital and analog IC design. Digital IC design is to produce components such as microprocessors, FPGAs, memories (RAM, ROM, and flash) and digital ASICs. Digital design focuses on logical correctness, maximizing circuit density, and placing circuits so that clock and timing signals are routed efficiently. Analog IC design also has specializations in power IC design and RF IC design. Analog IC design is used in the design of op-amps, linear regulators, phase locked loops, oscillators and active filters. Analog design is more concerned with the physics of the semiconductor devices such as gain, matching, power dissipation, and resistance. Fidelity of analog signal amplification and filtering is usually critical, and as a result analog ICs use larger area active devices than digital designs and are usually less dense in circuitry.

The TRS-80 Micro Computer System (TRS-80, colloquially known as the "Trash-80", later renamed the TRS-80 Model I to distinguish it from its successors) is a desktop microcomputer developed by American company Tandy Corporation and sold through their Radio Shack stores. Launched in 1977, it is one of the earliest mass-produced and mass-marketed retail home computers. The name is derived from Tandy Radio Shack Z80, referring to its Zilog Z80 8-bit microprocessor.

The TRS-80 has a full-stroke QWERTY keyboard, 4 KB DRAM standard memory, small size and desk area, floating-point Level I BASIC language interpreter in ROM, 64-character-per-line video monitor, and had a starting price of US$600 (equivalent to US$3,100 in 2024). A cassette tape drive for program storage was included in the original package. While the software environment was stable, the cassette load/save process combined with keyboard bounce issues and a troublesome Expansion Interface contributed to the Model I's reputation as not well-suited for serious use. Initially (until 1981), it lacked support for lowercase characters which may have hampered business adoption. An extensive line of upgrades and peripherals for the TRS-80 were developed and marketed by Tandy/Radio Shack. The basic system can be expanded with up to 48 KB of RAM, and up to four floppy disk drives and/or hard disk drives. Tandy/Radio Shack provided full-service support including upgrade, repair, and training services in their thousands of stores worldwide.