A design 
system for generating configuration information and associated 
executable code based on a customisation specification, which includes application information including application 
source code and customisation information including design constraints, for implementing an instruction processor using re-
programmable hardware, the 
system comprises a template generator for generating a template for each processor style identified as a candidate for implementation; an 
analyser for analysing instruction information for each template and determining instruction optimisations; a 
compiler for compiling the application 
source code to include the instruction optimisations and generate 
executable code; an instantiator for analysing architecture information for each template, determining architecture optimisations and generating configuration information including the architecture optimisations; and a builder for generating device-specific configuration information from the configuration information including the architecture optimisations. In another aspect, a 
management system for managing run-time re-configuration of an instruction processor implemented using re-
programmable hardware, comprises a configuration 
library containing configuration information for a plurality of instruction processor implementations; a code 
library for containing associated 
executable code for the implementations; a 
loader for loading application data and, as required, configuration information and associated executable code into re-
programmable hardware for implementation and execution of an instruction processor; a 
loader controller for signalling the 
loader to load application data and, as required, configuration information and associated executable code, and execute the executable code; a run-time monitor for obtaining run-time statistics relating to operation of the instruction processor; an optimisation determiner configured to receive the run-time statistics, and being operable to instruct the loader to load new configuration information and associated executable code for a new implementation into the re-programmable hardware; and an optimisation instructor for invoking the optimisation determiner.