基于單片機(jī)的溫濕度控制系統(tǒng)英文文獻(xiàn)-在線瀏覽
2025-07-18 12:00本頁(yè)面
【正文】 thers follow the philosophy, widely adapted for generalpurpose puters and microprocessors, of making no logical distinction between program and data memory as in the Princeton architecture, shown in .In general terms a singlechip microputer is characterized by the incorporation of all the units of a puter into a single device.Read only memory (ROM) ROM is usually for the permanent, nonvolatile storage of an applications program .Many microputers and microcontrollers are intended for highvolume applications and hence the economical manufacture of the devices requires that the contents of the program memory be mitted permanently during the manufacture of chips . Clearly, this implies a rigorous approach to ROM code development since changes cannot be made after manufacture .This development process may involve emulation using a sophisticated development system with a hardware emulation capability as well as the use of powerful software tools.Some manufacturers provide additional ROM options by including in their range devices with (or intended for use with) user programmable memory. The simplest of these is usually device which can operate in a microprocessor mode by using some of the input/output lines as an address and data bus for accessing external memory. This type of device can behave functionally as the single chip microputer from which it is derived albeit with restricted I/O and a modified external circuit. The use of these ROM less devices is mon even in production circuits where the volume does not justify the development costs of custom onchip ROM[2]。there can still be a significant saving in I/O and other chips pared to a conventional microprocessor based circuit. More exact replacemen
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