The absence of in-circuit emulation facilities on the Ferranti FDS-10 microprocessor development system may force unacceptable restrictions on the development of hardware and software for an FlOO-L-based project. The disadvantages of this lack of support are discussed and a solution is presented, in the form of a pseudo-emulation facility, which provides many of the features normally associated with in-circuit emulation. Development of a special-purpose interface circuit, allowing communication between the FDS-10 and the target hardware and software, is described and details are given of the monitor program which runs in the FDS-10 and which controls the hardware via the interface.