1. ASYNCHRONOUS PROCESSORS | The Clockless Future
Akshit Arora (101303012) | Ankit Goyal (101303022)
ABSTRACT
The synchronous processor chips of
computers use a clock to time the entire
chip. But this clock is also the cause of
speed and power consumption
headaches. Here is how an asynchronous
chip overcomes these problems by
eliminating the clock altogether.
WHAT ARE ASYNCHRONOUS
PROCESSORS
An asynchronous circuit, or self-timed
circuit, is a sequential digital logic circuit
which is not governed by a clock circuit
or global clock signal. Instead they often
use signals that indicate completion of
instructions and operations, specified by
simple data transfer protocols.
HISTORY
• 1952 : ILLIAC I and ILLIAC II (University
of Illinois)
• 1960 : PDP6 (Programmed Data
Processor-6) from Digital Equipment
(DEC)
• Late 1970s : until the arrival of VLSI
• 1988 : first single-chip asynchronous
microprocessor was designed at
Caltech
• 1993 : ARM processor (Amulet)
(University of Manchester)
WHY ASYNCHRONOUS
PROCESSORS
World’s first flexible
8-bit asynchronous
microprocessor
developed by Seiko
Epson using low-
temperature
polysilicon thin-film
transistors on a
plastic substrate.
HISTORY
• 1994 : 8-bit microprocessor (TITAC)
Tokyo Institute of Technology
• 1997 : Amulet2e and TITAC-2 (a 32-bit
microprocessor) And Caltech group
designed the MiniMIPS
• 2004 : ACT11, an 8-bit asynchronous
chip (Epson)
• 2014 : IBM announced a SyNAPSE-
developed chip
RESULTS FROM EPSON’S
INVENTION
CONCLUSION
So far, most of the efforts have
been made to redesign already
available architectures without a
clock.
Asynchronous design is competitive
with the best synchronous design in
power efficiency and is close in
performance and silicon area.
• Higher Performance
• No global clock
• proceed data at appropriate rate of
environment
• Do not propagate local delay globally
• Better Power Efficiency
• Only activating functional units
consume power
• Inactivated parts remain in “stand-
by” state
• No wasteful power dissipation by
glitches
• Smaller Chip Size
• Less high-frequency EMI
components due to small
amplitude and wide current peaks
1. Make a stable 8-bit
microprocessor composed of
32,000 LTPS-TFTs
2. Achieve energy consumption
70% lower than the synchronous
design
3. Reduce electromagnetic
radiation by 20dB.