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VAX-11/780是微程序化的32位超级小型计算机。它采用水平型微指令,以提高并行操作的能力。微指令长96位(外加3个校验位),分别存于4K的PCS和2K的WCS中,其中微地址UPC12=0,为PCS;UPC 12=1,为WCS。微指令可分成30个微字段。 为了提高微字段的使用效率,有的微字段可用以实现相互独立的两种不同功能。如KMX字段可在一条微指令中作为常数选择控制,在另一条微指令中又可作为ID BUS地址使
The VAX-11/780 is a micro-programmed 32-bit superminiature computer. It uses horizontal microinstructions to improve the ability to operate in parallel. The microinstruction is 96 bits long (plus 3 parity bits) and is stored in 4K PCS and 2K WCS respectively. The micro address UPC12 = 0 is PCS; UPC 12 = 1 is WCS. Micro instructions can be divided into 30 micro-fields. In order to improve the efficiency of the use of micro-fields, some micro-fields can be used to achieve two different functions independent of each other. If the KMX field can be selected as a constant control in a microinstruction, and can be used as an ID BUS address in another microinstruction