  Efficiency in embedded systems is paramount to achieve high performance while
consuming less area and power. Processors in embedded systems have to be
designed carefully to achieve such design constraints. Application Specific
Instruction set Processors (ASIPs) exploit the nature of applications to design
an optimal instruction set. Despite being not general to execute any
application, ASIPs are highly preferred in the embedded systems industry where
the devices are produced to satisfy a certain type of application domain/s
(either intra-domain or inter-domain). Typically, ASIPs are designed from a
base-processor and functionalities are added for applications. This paper
studies the multi-application ASIPs and their instruction sets, extensively
analysing the instructions for inter-domain and intra-domain designs. Metrics
analysed are the reusable instructions and the extra cost to add a certain
application. A wide range of applications from various application benchmarks
(MiBench, MediaBench and SPEC2006) and domains are analysed for two different
architectures (ARM-Thumb and PISA). Our study shows that the intra-domain
applications contain larger number of common instructions, whereas the
inter-domain applications have very less common instructions, regardless of the
architecture (and therefore the ISA).
