In Fig. 4-6, the B bus register is encoded in a 4-bit field, but the C bus is represented as a bit map. Why? In Fig. 4-6 there is a box labeled “High bit.” Give a circuit diagram for it. When the JMPC...

In Fig. 4-6, the B bus register is encoded in a 4-bit field, but the C bus is represented as a bit map. Why? In Fig. 4-6 there is a box labeled “High bit.” Give a circuit diagram for it. When the JMPC field in a microinstruction is enabled, MBR is ORed with NEXT_ADDRESS to form the address of the next microinstruction. Are there any circumstances in which it makes sense to have NEXT_ADDRESS be 0x1FF and use JMPC?