【導讀】序能被單片機執(zhí)行。這種通用程序具有將數(shù)據(jù)寫到數(shù)據(jù)處理和，或存儲設備的基。本功能，寫入功能用于裝載程序，因為裝載程序并非永久地存儲在只讀存儲器重，在微處理器系統(tǒng)中，處理是由微處理器本身完成的。而進入和出自系統(tǒng)的信息傳輸則是利用特定的輸入/輸出（I/O）電路。在存儲器中，而在固定的時間間隔下由微處理器控制增值。過程的軟件包含實現(xiàn)計數(shù)器功能的單元。由于系統(tǒng)幾乎完全由軟件所定義，所以。規(guī)工程中相似的構造和維護問題。按寫入時的相同次序，所以有“隨機”存取存儲器。丟失，并通常用來保存規(guī)定微處理器化系統(tǒng)運轉過程的程序。一樣被讀取，但與RAM不一樣的是不能用來存儲可變的信息。被廣泛使用的可編程ROM可利用特殊紫外線燈察除，并被成為E. PROM，即可察除可編程只讀存儲器的縮寫。燈而用電察除，所以稱為電可察除可編程只讀存儲器EEPROM。的I/O裝置不用主微處理器的直接干預，就可實施非常復雜的操作。微計算機的另一主要工程應用是在過程控制中。

　　

【正文】 t the time, but must first be returned to a place where a test device is available. Troubleshooting a microcontrollerbased system in this way is timeconsuming, irksome and costly. To avoid the need for direct action on the microcontrollerbased system each time the application program executed by the microcontroller of the system is changed, it is standard practice to use a downloadable read only memory to store the application program, a loading program being written into a maskprogrammed read only memory of the microcontroller, The maskprogrammed read only memory of the microcontroller is integrated into the microcontroller and programmed once and for all during manufacture of the microcontroller. To change the application program the microcontroller is reset by running the downloading program. This downloading program can then municate with a workstation connected to the microcontroller by an appropriate transmission line, this workstation the new application program to be written into the microcontroller, The downloading program receives the new application program and loads it into a read only memory external to the microcontroller. Although this solution avoids the need for direct action on the microcontroller=based system (which would entail removing from the system the reprogrammable read only memories containing the application program, writing into these memories the new application program using an appropriate programming device and then replacing them in the system), it nevertheless has a major drawback, namely specialization of the microcontroller during manufacture. Each type of reprogrammable memory is associated with a different downloading program because the programming parameters (voltage to be applied, duration for which the voltage is to be applied) vary with the technology employed, The downloading program is written once and for all into the maskprogrammed internal memory of the microcontroller and the latter is therefore restricted to using memory ponents of the type for which this downloading program was written. In other words,the microcontroller is not a standard ponent and this increases its cost of manufacture. One object of the invention is to overe these various drawbacks of the prior art, To be more precise, an object of the invention is to provide a microcontroller circuit which can verify quickly, simply, reliably and at low cost the operation of a system based on the microcontroller. Another object of the invention is to provide a microcontroller integrated circuit which can accurately locate the defective ponent or ponents of a system using the microcontroller in the event of dysfunction of the system. A further object of the invention is to provide a microcontroller integrated circuit which avoids the need for direct action on the microcontrollerbased system to change the application program, whilst remaining standard as regards the type of memory ponent with which it can be used in a system.