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现在介绍控制器,也就是谈谈为什么计算机能自动工作。为了讨论方便起见,假想有这样一台计算机,它的工作指标是:二进位定点记数制、字长 n=19位、符号位1位、单地址指命系统、并行操作方式、用磁心存储器(设它的存储量为2~6=64字,即一共有64个存储单元,存取周期为8微秒)。运算器中有两个数码寄存器(寄存器_1 和寄存器_2)及一个累加法器(图29);做加减法运算时,加数和减数放在寄存器_1;做乘法时,乘数放在寄存器_2,被乘数放在寄存器_1,运算结束后,在累加法器中得到乘积的前 n 位(连符号位在内共20位),在寄存器_2 中得到乘积的后 n 位;做除法时,被除数放在累加法器,除数放在寄存器_1,商放在寄存器_2,故有时可以把寄存器_2 称为乘数-商寄存器。
Now introduce the controller, that is to say why the computer can work automatically. For the sake of discussion, it is assumed that there is such a computer that its working indicators are: binary fixed-point counting system, word length n = 19 bits, sign bit 1, single-address pointing system, parallel operation mode, (Let it be the storage capacity of 2 to 6 = 64 words, a total of 64 storage units, the access cycle of 8 microseconds). The arithmetic unit has two digital registers (register_1 and register_2) and an accumulator (Figure 29). When adding and subtracting, the addend and subtrahend are placed in register_1. When multiplication is performed, multiply The number is placed in register_2 and the multiplicand is placed in register_1. After the operation is completed, the first n bits of the product (with the sign of 20 bits in total) are obtained from the accumulator, and the product of After the n-bit; Do division, the dividend on the cumulative adder, divisor on the register _1, quoted on the register _2, so sometimes register _2 can be called multiplier - quotient register.