The show controllers command provides hardware-related information used to troubleshoot and diagnose issues with Cisco router interfaces. The output of the command is as follows:
routerA# show controllers serial 0 HD unit 1, idb = 0x1C44E8, driver structure at 0x1CBAC8 buffer size 1524 HD unit 1 V.35 DTE cable, clock rate 64000

The preceding output indicates that a V.35 DTE cable is currently connected to interface Serial 0, and that a clock rate of 64000 bps has been detected from the DCE (the other side of the serial link). When the other end is a CSU/DSU, as is usually the case, the clock rate is provided by the CSU/DSU. The clocks stopped portion of the following output would indicate that a clock rate has not been detected from the DCE:
routerA# show controllers serial 0 HD unit 1, idb = 0x1C44E8, driver structure at 0x1CBAC8 buffer size 1524 HD unit 1 V.35 DTE cable, clocks stopped

This condition would be rectified by configuring a clock rate on the DCE router.

The show interfaces, show ip interface, and show interface switchport commands do not display any hardware-related information, such as connected cable types.

The show interface dce command is incorrect because this is not a valid Cisco IOS command.