lecture3

CPE319 LECTURE NOTES WINTER 1998 PART THREE

INTRODUCTION TO DIGITAL DESIGN IN THE 21^ST CENTURY - A PERSPECTIVE!

Cost = K₁V+K₂L V=# of Variables (fixed) and L=# of literals. Minimize L for least cost.
Quine and McCluscky develop tabular reduction
Karnaugh develops map method

Faster
Expensive
Not very reliable (burned out)
EINAC the first Vacuum Tube Computer (in USA), followed by UNIVAC, firs commercial computer, circa 1951.
Minimum cost procedures - I don't remember!

Still faster
Less Expensive (especially in terms of power needed)
Quite reliable (as soon as good transistors were available)
Early computers: IBM 7090, IBM1620, UNIVAC Missile Guidance Computers. DEC PDP8 first successful minicomputer using transistor technology
Minium cost procedures _ I don't remember!

Somewhat faster (faster transistors)
Considerably less expensive
Even more reliable (less solder joints)
Many computer using this technology, many of them minicomputers. HP2100 series used early IC's as did the DEC PDP8I.
Minimum Cost procedures

Cost = K(2P+L) where P=# of product terms and L= # of literals. Twice as inportant to reduce product terms as to reduce literals. This relation comes from the observed fact that SSI costs are essentially dependant on the number of pins in the DIP.
Since reducing L to a minimum has to reduce P as well, Relay design techniques were still applied!

Somewhat faster since PLD's use less levels of logic that SSI gates
Somewhat less expensive since fewer IC's needed
Somewhat more reliable (less IC's)
By now computers using microchips. Digital design used for special purpose digital functions.
Minimum cost procedures change dramatically. If the design fits in the desired PLD, all implementations cost the same (same IC!). Only consideration is the number of product terms. Number of literals immaterial.
Hardware Design/Description Languages (HDL) come into being since some sort of software is required to "burn" the PLD. As time goes by, the software becomes more sophisticated doing more than simply producing a JEDEC Fuse file.

Still faster since delays inside a CPLD or FPGA are considerably less than between chips.
Probable less expansive, but who knows? Who cares?
Still more reliable (one or only a few IC's for the entire system
Used for special purpose functions. Could be used to fabricate a microprocessor, but probably not.
With the rapid change in technology, fabrication costs are often not the critical factor. Often it is more important to get the product on the market fast (before the competition). Synthesis costs very difficult to estimate. Not necessary anyway. See NOTES07!
HDL becomes more sophisticated. Several HDL's become standard, VHDL and Verilog being the most common. Digital design becomes much more abstract (i.e., we don't look at the individual logic gates and flip-flops anymore (not very much, anyway).

The 21^st century. By the time you get an engineering design job, the 21^st century will be here (or almost here). Digital design in the 21^st century will be radically different, relying more and more heavily on HDL's and design software. To be ready, you need to know one (or more) HDL reasonably well. So there's the goal of this class.