rite a symbolic microprogram routine for the ISZ (increment and skip if zero) instruction defined in Chap. 5 (Table 5-4). Use the microinstruction format of Sec. 7-3. Note that DR = 0 status condition is not available in the CD field of the computer defined in Sec. 7-3. However, you can exchange AC and DR and check if AC = 0 with the Z bit. rite a symbolic microprogram routine for the ISZ (increment and skip if zero) instruction defined in Chap. 5 (Table 5-4). Use the microinstruction format of Sec. 7-3. Note that DR = 0 status condition is not available in the CD field of the computer defined in Sec. 7-3. However, you can exchange AC and DR and check if AC = 0 with the Z bit