Many bottom end 8086-based MS-DOS machines actually use the NEC Corp V30 or 8-bit bus V20 microprocessors, which are code-compatible with the Intel Corp originals, but offer somewhat better performance as a result of cleaning up of the design – and now NEC has come out with highly-integrated single chip implementations of the entire XT processor board that are likely to appeal to designers of cheap machines, particularly handheld computers, where an MS-DOS capability is required. The parts are the V41 and V51, also dubbed DOS Engines, the 41 using the 8-bit bus V20HL core, the 51 using the full 16-bit V30HL. They are fabricated in 0.8 micron fully static CMOS with single 3V power requirement, and integrate clock generator, Intel 8237A-compatible Direct Memory Access controller, 8259A-compatible interrupt controller, and 8254-compatible counter-timer, XT keyboard interface or PS/2 Model 30 keyboard and mouse interface, and programmable input-output chip select logic. They draw 5mA per MHz at 3V, and the fastest they can be clocked is 16MHz, for which 5V is needed. They include EMS 4.0 memory expansion and support up to 16Mb. Pricing is under $20 when you order 100,000 and there is a sea-of-gates version for custom versions, where which NEC promises 10 to 14 weeks’ turnround time.
