© 2000 Scenix Semiconductor, Inc. All rights reserved. 13 SX User’s Manual Rev. 3.1 www.scenix.com Chapter 1 Overview Programming and Debugging Support •   On- chip in-system programming support through serial or parallel interface
•   In-system serial programming via oscillator pins
•   On-chip in-system debugging support logic
•   Real-time emulation, full program debug, and integrated development environment offered by third party tool vendors Software Support •   Library of off-the-shelf Virtual Peripheral modules
•   Examples of Virtual Peripheral integration
•   Evaluation Kits for communication intensive applications 1.3     Architecture The SX devices use a modified Harvard architecture. This architecture uses two separate memories
with separate address buses, one for the program and one for data, while allowing transfer of data
from program memory to SRAM. This ability allows accessing data tables from program memory.
The advantage of this architecture is that instruction fetch and memory transfers can be overlapped
with a multi-stage pipeline, which means the next instruction can be fetched from program memory
while the current instruction is being executed using data from the data memory.
Scenix has developed a revolutionary RISC-based architecture and memory design techniques that is
20 times faster than conventional MCUs, deterministic, jitter free, and totally reprogramable.
The  SX  family  implements  a  four-stage  pipeline  (fetch,  decode,  execute,  and  write  back),  which
results  in  execution  of  one  instruction  per  clock  cycle.  At  the  operating  frequency  of  100  MHz,
instructions are executed at the rate of one per 10-ns clock cycle. 1.4 The Virtual Peripheral Concept Virtual Peripheral concept enables the “software system on a chip” approach. Virtual Peripheral, a
software module that replaces a traditional hardware peripheral, takes advantage of the Scenix archi-
tecture’s high performance and deterministic nature to produce same results as the hardware periph-
eral with much greater flexibility. The speed and flexibility of the Scenix architecture complemented with the availability of the Virtual
Peripheral library, simultaneously address a wide range of engineering and product development con-
cerns. They decrease the product development cycle dramatically, shortening time to production to as
little as a few days.
Scenix’s time-saving Virtual Peripheral library gives the system designers a  choice of ready-made
solutions, or a head start on developing their own peripherals. So, with Virtual Peripheral modules
handling established functions, design engineers can concentrate on adding value to other areas of the
application.
The concept of Virtual Peripheral combined with in-system re-programmability provides a powerful
development platform ideal for the communications industry because of the numerous and rapidly
evolving standards and protocols.