By BDTI, 12/10/2004
LSI Logic recently added two new processors, the ZSP200 and the ZSP540, to
its ZSP family of superscalar DSP cores. With the addition of these cores, the
ZSP family has become the largest family of code-compatible DSP cores available
today. As with existing family members—the ZSP400, ZSP500, and ZSP600—the
names of the new cores reflect their levels of parallelism. The ZSP200 offers
less parallelism than the ZSP400, while the ZSP540 falls between the ZSP500
and ZSP600 in terms of parallelism.
In some ways, the ZSP200 resembles a ZSP400 cut in half. For example, the ZSP400
contains two multiply-accumulate (MAC) units, while the ZSP200 offers one MAC
unit. However, the ZSP200 retains both of the ALUs found in the ZSP400. The
ZSP200 also adds hardware loop support that is missing in the ZSP400. These
features will likely make the ZSP200 faster than might be expected for a single-MAC
version of the ZSP400.
The ZSP200 targets low-cost, low-power signal-processing applications. Based
on BDTI’s analysis of the older ZSP400, the ZSP200 is likely to be highly
competitive in these applications. Memory use is a major contributor to system
cost, and the ZSP400 is one of the most memory-efficient processors BDTI has
benchmarked. The ZSP400 is also one of the most energy-efficient cores BDTI
has benchmarked. It will be interesting to see if the ZSP200 can surpass the
high marks set by the ZSP400.
As its name suggests, the ZSP540 is similar to the ZSP500. The main differences
between the cores are that the ZSP540 doubles the number of MAC units from two
to four and doubles the data memory bandwidth from 64 bits to 128 bits per cycle.
The ZSP540 also adds hardware loop support not found in the older cores. These
features will make the ZSP540 faster than the ZSP500 and possibly even faster
than the ZSP600. This possibility casts doubt on the future of the ZSP600. It
will be interesting to see how LSI Logic evolves the ZSP600 to address this
apparent overlap in performance.
For an in-depth
analysis of the older ZSP500, see BDTI’s report Inside
the LSI Logic ZSP500. Excerpts from the report are available online
at http://www.bdti.com/articles/zsp500_summary_report.pdf.
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