通用数字计算机 SD-2有一个存取时间为20微秒的磁心存贮器和一个存贮微程序的二极管存贮器。机器的字长为19位,指令系统有31条指令;程序存放在磁心存贮器中。每条指令中的地址码用14位,其中12位用作主地址,一位用作变址地址,另一位作间接地址。第32条指令是无地址指令,用来完成不需要地址的操作。机器采用晶体管逻辑电路。这台用微程序 The Universal Digital Computer SD-2 has a magnetic core memory with 20 microsecond access time and a diode memory for storing microprograms. The machine’s word length is 19 bits and the instruction system has 31 instructions; the program is stored in the core memory. The address code in each instruction uses 14 bits, of which 12 bits serve as the master address, one for the indexed address and the other as the indirect address. The 32nd instruction is an addressless instruction that is used to complete an operation that does not require an address. The machine uses transistor logic. This micro-program