We are developing techniques for building retargetable debuggers. Our prototype, 1db, debugs C programs compiled for the MIPS R3000, Motorola 68020, SPARC, and VAX architectures. It can use a network to connect to faulty processes and can do cross-architecture debugging. 1db's total code size is about 16,000 lines, but it needs only 250–550 lines of machine-dependent code for each target. 1db owes its retargetability to three techniques: getting help from the compiler, using a machine-independent embedded interpreter, and choosing abstractions that minimize and isolate machine-dependent code. 1db reuses existing compiler function by having the compiler emit PostScript code that 1db later interprets; PostScript works well in this unusual context.