【正文】
t for ROM devices can be obtained in the form of variants with 39。 EPROM(Erasable programmable ROM )sockets or devices with EPROM instead of ROM 。 it is unnecessary to make distinction between RAM and processor register as is done in the case of a microprocessor system since RAM and registers are not usually physically separated in a microputer .Central processing unit (CPU). The CPU is much like that of any microprocessor. Many applications of microputers and microcontrollers involve the handling of binarycoded decimal (BCD) data (for numerical displays, for example) ,hence it is mon to find that the CPU is well adapted to handling this type of data .It is also mon to find good facilities for testing, setting and resetting individual bits of memory or I/O since many controller applications involve the turning on and off of single output lines or the reading the single line. These lines are readily interfaced to twostate devices such as switches, thermostats, solidstate relays, valves, motor, etc.Parallel input/output. Parallel input and output schemes vary somewhat in different microputer。這兩種特性在單片機中得到了充分的體現(xiàn)。只讀存貯器(ROM) ROM是通常的永久性的,非應(yīng)用程序的易失性存儲器。這一發(fā)展過程可能涉及仿真,使用硬件仿真功能以及強大的軟件工具使用先進的開發(fā)系統(tǒng)。但仍然可以在我節(jié)省大量成本I/ O和其它芯片相比,可在與39。EPROM(可擦除可編程只讀存儲器)插座或存儲器,而不是ROM器件。隨機存取存儲器(RAM),但具有相同的特征寬度(4,8,16 比特等)作為處理器。中央處理單元(CPU)(十進制處理(BCD)的數(shù)據(jù)為例)數(shù)字顯示,因而,常??梢园l(fā)現(xiàn)該CPU是很適合處理這種類型的數(shù)據(jù)。 / O線直接連接到適當?shù)脑O(shè)備,例如,熒光顯示器,也可以提供足夠的電流, / O端口,其他組件將作為系統(tǒng)總線配置為允許片外存儲器和I / O擴展。串行輸入/輸出。這可以作為一個硬件設(shè)施或U(擰)藝術(shù)(通用執(zhí)行(同步)異步接收器/發(fā)送器)減輕處理器(和應(yīng)用程序)(停止位,奇偶校驗等)和負載號碼(或讀?。?,串行發(fā)送器(或接收),然后由硬件電路完成。這可以由每個程序中的執(zhí)行時間分支認真評估,但除最簡單的程序外,他的工作效率不高。這種類型的定時器通常在所要求的數(shù)量可重載中應(yīng)用。這將緩解重新加載計數(shù)器和評估所用的時間,計時器重新啟動之前這是必要的。這個設(shè)備通常有一個特殊的輸入引腳,可直接驅(qū)動計數(shù)器。許多時鐘電路,還具有電阻和低電容工作成本定時元件,也可以從外部源驅(qū)動。