Notes

Note 1: Augarten (1984) points out that there weren't any courses in solid state physics courses in any of the big science and engineering universities in the U.S. until the mid-1950's.

Note 2: Because silicon was more heat resistant, it became of great interest to the military. increased interest of the military in silicon based semiconductor electronics was an important economic factor in the growth of the semiconductor industry in the early days.

Note 3: The claim was made by David Florida that the DRTE computer was the first solid state general purpose computer designed and built in Canada. The development of the system evolved from 1956 to 1960. Though a partial system consisting of "550 transistors and 2500 diodes was tested in 1957 the full system wasn't fully operational until some time in 1960. In this same period Ferranti-Packard was designing and building the Gemini computer for Trans-Canada's Reservec I system. Therefore there is some doubt as to which was the first general purpose solid state computer built in Canada. However, it must be added that the DRTE computer was a more advanced machine from the point of view of scientific computations.

Note 4: I have not used the original notation used by DRTE electronics group. They adopted their own symbolic notation for semiconductor devises. In the 1950's transistor technology was still in great flux and as a consequence there was considerable variation in notations used to represent transistors. In the 1957 IRE-AIEE conference on Transistor and Solid State Circuits there were 5 different notations used:

Note 5: (Richards,l967)

Note 6: "[In Chalk River] I learned that you don't want your trigger fired too easily because otherwise every bit of interference would be counted. Many of the early nuclear counters counted electrical razors and everything else in the place. For instance if you are looking for alpha emission in urine, you are only looking for a half dozen particles a day. This sort of thing puts the iron into your soul and so these trigger circuits had a reasonable threshold"(Moody,l975:15)

Note 7: In a paper delivered in 1960, Florida listed 11 desirable features incorporated in the DRTE computer:a) Floating Point Arithmetic
b) 3 Address Code
c) Simple Iteration
d) Simple Sub-routine In And Out
e) Random Access Core Memory
f) Decimal/Binary and Binary/Decimal Conversions in Separate Unit
g) Index Registers
h) Division and Square Root
i) Mnemonic Order Code
j) Small Physical Size
k) Low Power Consumption

Note 8: "If this failure rate is 1% per annum, then by using 10,000 components a failure must be expected about once every 3 days; with 100,000 components there would be a failure, on an average, every 8 3/4 hours. If, for the purpose of the equipment, this is intolerable then the number of components just cannot be used and a simpler system must be considered. On the other hand, if the component failure rate can be reduced to 0.01% per annum instead of 1%, then 100,000 components can be used with a failure only once every 5 weeks" (Florida,1960:300).

Note 9: The failure rates of the various components used in the experimental logic unit are summarized in (Florida,1960:299):

Component	Transistors	Diodes	Resistors	Capacitors
Number in use	550	2500	1700	700
Number Failed in 2 1/2 years	0	1	1	2
% Failure Rate Per Annum	0	0.016	0.023	0.11

Note 10: "An interesting example, is the square root where the hardware performed the square root very efficiently and very well. But there is a problem with all square root taking machines. You can't take the square root of negative numbers. Now the only thing the DRTE computer would be able to do when asked to take the square root of a negative number would simply be to indicate that it was an error. If you do that with software, you can make a decision about what you are going to do when you are asked to take the square root of a negative number. Some machines simply come back us and say: 'Look that's an error, I can't do it. Mr. Programmer go away and fix your problem'. But you could also say: 'Look for this h particular problem. If I happen to ask you to take the square root of a negative number, what I really would like you to do is take the square root of the corresponding positive number and put a minus sign in front of the answer'. It's not mathematica7ly 1 correct, but for some problems that may be exactly what you want to do. By building the square root into the hardware you've taken away that option" (Lake, 1985:6-7).