VLSI Systems Design CS250 Fall 2020 John Wawrzynek with Arya Reais Parsi Lecture 02 History CS250 UC Berkeley Fall 20 Why is it CS250 and not EE250 We answer that with a course history with a few embedded lessons Warning What follows is principally from memory I ve done my best to be accurate but some errors or misinterpretations might exist Starts in 1958 with the invention of the Integrated Circuit independently by Robert Noyce co founder of Fairchild Semiconductor Corporation and Jack Kilby engineer at Texas Instruments Bob Noyce Fairchild Jack Kilby Texas Instruments Lecture 02 History 2 CS250 UC Berkeley Fall 20 IC Design in the 70 s and early 80 s Move from LSI to VLSI Circuit design layout and processing tightly linked Logic design and layout was random Chip design was the domain of industry Fairchild Intel Texas Instruments These were IC processing companies Those who controlled the physics controlled the creative agenda Federico Faggin Ted Ho Stan Mazor Introduced to help sell memory chips Lecture 02 History The Intel 4004 microprocessor which was introduced in 1971 The 4004 contained 2300 transistors and performed 60 000 calculations per second Courtesy Intel 3 CS250 UC Berkeley Fall 20 Meanwhile at Caltech Carver Mead was designing and building prototype ICs with help from his friends at Intel His background was in physical electronics invented several semiconductor devices such as the GaAs MESFET but was deeply interested in the interaction of physical implementation and the higher level design of electronic systems Listen to the technology nd out what it s telling you Lecture 02 History 4 CS250 UC Berkeley Fall 20 CS At Caltech Ivan Sutherland became founding head of the computer science division at in 1974 after leaving E S He and Mead teamed up to get the division o the ground making IC design Integrated Systems a key component of the research and teaching My take These two believed that IC design was at the heart of computer science because CS was largely about inventing and building computing devices The future of computing was integrated circuits Very exible boundless growth potential Gordon Moore had predicted an exponential grow curve with no end in sight Close to pure thought with few constraints and nasty realities The potential of VLSI was not going to be reached with the status quo in industry Worked together over the next 10 years to establish the faculty industrial ties curriculum research projects with silicon structures as a key component Lecture 02 History 5 CS250 UC Berkeley Fall 20 Pushing forward 1 The reality of integrated circuits Wires are expensive area delay power transistors are cheap Pre ICs the opposite was true Therefore plan the communication and the layout Exploit locality think about the geometry of the problem from the beginning Choose algorithms designs accordingly Algorithms designs represented as communication graphs in a large number of dimensions not a good idea Lecture 02 History 6 CS250 UC Berkeley Fall 20 Pushing Forward 2 Traditionally IC design had been strati ed Algorithm architecture Micro architecture Circuit design Layout Put IC design expertise into the hands of those best quali ed to take advantage of its potential Those with intimate knowledge of computation and algorithms computer scientists Emergence of the tall thin designer Spans all levels of the design and implementation stack Would lead to more successful innovation and highly optimized designs Lecture 02 History 7 CS250 UC Berkeley Fall 20 Pushing Forward 3 How to enable system architects Managing the complexity was the key challenge Manipulating multiple levels of design complexity was di cult and projected to get much worse looking forward remember Moore s Law Providing universal access to IC fabrication Solutions 1 Ideas from software 2 New design representations 3 Computer aided design tools 4 Silicon foundries 5 Education All inter linked Lecture 02 History 8 CS250 UC Berkeley Fall 20 Ideas from Software help manage complexity Structured Programming was getting popular Dijstra el al No goto statements Block organization Use of hierarchy abstraction sub routines Structured Design for ICs Exploit regularity and symmetry Use and reuse common sub blocks ip ops gates Represent designs hierarchically arithmetic etc Lecture 02 History 9 CS250 UC Berkeley Fall 20 Previously to generate the mask information for fabrication the Design Representations 1 designed needed intimate knowledge of the manufacturing process Even once this knowledge was distilled to a set of Geometric Design Rules this set of rules was voluminous with many special cases Mead and associates come up with a much simpli ed set of design rules single page description A sort of API or abstraction of the process back end processing could automatically convert this information into masks Su ciently small set that designers could memorize Su ciently abstract to allow process engineers to shrink the process and preserve existing layouts Process resolution becomes a parameter Lecture 02 History 10 CS250 UC Berkeley Fall 20 Scalable CMOS Design Rules Created with the transition from nMOS to CMOS a much nicer technology around 1985 Little changed over the years Lecture 02 History 11 CS250 UC Berkeley Fall 20 Design Representations 2 Caltech Intermediate Form CIF Capture layout information needed to generate masks and process ASCII text le with geometric primitives and hierarchical de nitions Simple and human readable Easy to generate and parse Common sub blocks could be reused from one design to the next output pad drivers etc A sample CIF wire statement The statement is W25 100 200 100 100 200 200 300 200 Lecture 02 History 12 CS250 UC Berkeley Fall 20 Design Representations 3 Previously designed were represented by hand drawings Then masks where made by transferring drawings to rubylith Base layer of heavy transparent dimensionally stable Mylar A thin lm of deep red cellophane like material covers the base layer Patterns formed by cutting often by hand the transparent covering Using an electronic format CIF meant Layouts easily stored and transmitted Written to tape and transferred to Transmitted over the network new Software could automatically check for Generated from a program huge idea manufacturer tape out idea back then layout errors 13 Lecture 02 History CS250 UC Berkeley Fall 20 Design Representations 3 Simpli ed approach extended upward Sticks diagrams for layout Simultaneously captures