CPSC 409 Oct 7 – Transcript

00:04out of essentially simulated relays. These aren't even from the Bell Lab junk pile. As he actually completes this very simple prototype, two bit accumulator, describe it as it stores two bits, doesn't perform any functions. Um, Stitz's boss essentially was told about the problems that the company was having where it was just limiting operations.

00:28it couldn't perform calculations that it needed to which is coental because you'd see where it's leading. Um the complex number calculator then came out of this.

00:40Now in this case um Stipps was good at tinkering but he wasn't he couldn't build the full-blown project. So he had someone else appointed as the manager of the pro project.

00:57I actually should mention something over here. This is something I'd considered if the class wasn't so bloody big as an alternative to um to just exams. Assignments are just hopeless to or essays. It's just too many to mark for one person. There's no marking support. Uh Chris Wapel had someone build the uh what is it? The step drum, but his class was what? 40 people.

01:23Uh marking just so many of these would be too much. And the other thing is with the step drum things like that it requires that you're good with your hands. You have to build it with precision. In this case this the worst thing that might happen is you zap yourself. But if you have a low 9vt battery probably wouldn't have issues.

01:40But the class is still too big to imagine 175 of these things. It's just marking not so bad but fill up the office area. So I that twigged my memory because I was thinking okay it the stimits could build these small prototypes really students could build these prototypes as well too but actually designing something this is just an accumulator that performs basic

02:07mathematical operations is actually trickier in a class that um we used to have 400 level class you're designing using logic gates a processor and I actually designed one myself that was um about 1,000 or so gates and it could store I think four bit numbers but it could perform mathematic operations like addition subtract I think all the math operations maybe a bit more as well as comparator and it was actually fairly

02:32complex process but I didn't wire it I used a software uh simulation where I I just laid out the gates so came up with the idea but Williams basically had the additional background to be able to design circuits and there's it's it's a fair challenge to do that and his had the additional um complexity

03:00where it was dealing with complex numbers. Mine essentially was just um integers. So the complex number was completed and it was actually quite useful for the operations of the phone company. a very primitive device in terms of gates um its hardware complexity but it was still quite useful.

03:24It performed the operations that my simple CPU could do, but it also had I don't know how they'd implement that complex numbers and there looked at never bothered to look at it myself actually and my couldn't even handle floating point the operation of the complex number calculator. We had essentially a person working at a teletype. Remember I said with zuza there was some um human form

03:49person typing in at a standard It wasn't a querty keyboard, but the standard of that day. So, he had someone who essentially was a clerk typist, a secretary who was typing in stuff. Um, it would send the send the result to the complex number calculator uh in a wired form and then after it computed the result, we get a print out of the results here. And it

04:16took a few minutes to be able to complete it in yearly form. This was still a useful thing. this person didn't know about calculations. Um, she in this case that's the way it was in terms of gender and jobs was someone who was just good at typing without knowing what what she was typing in. Significance.

04:36One significance is I put the quote here. It allowed for or this asteris more than one terminal to be connected. It simulated it. So we could have a number of operators that were remote. They were they could be actually quite far apart. In one case they did a test where it was 500 km apart. We'll talk about

05:02and in principle any of them could connect. Now keep in mind that this is the phone company the American phone company and they use landlines and they didn't have anything fancy like the was it call waiting dead. So if a basic call even with a cell phone you call someone up it's uh a connection you have to actually lock that connection between your device and the other person's device um someone else can

05:28theoretically call any distance but they get a busy signal. So the first machine to allow for more than one well only one more than one means that in principle any of them could call in remotely but only one had that connection because it wasn't like a UDP the internet where you can have mobile people log on to a server. It's not just one person, one connection.

05:53The other ones would get a busy signal. In a way, I don't know how much you've actually learned about how operating systems work now because they really paired down the assembly programming course, but before they had processors that and ignoring even multi multi-CPUs, if you had a processor that could handle multiple threads, that's what right now it can handle

06:20multiple threads. potentially it might have two separate ALUS before that if it was just a single processor that didn't have multi-threading capability how would it do it and this is where the paired down version of assembly you almost certainly have an act I certainly I'd say I'd bet money on this that you have to learn how to do this but what we used to have in the assembly was simulating a processor that only handles one process at a time and you actually

06:48had to write this part of the operating system but assembly along those device drivers. How it would do it is it could be drawing a graphic and that takes up the processor's time. But what students had to do in those days was write device drivers, the mouse and keyboard. So it produced an interrupt. It literally interrupted the operating system. And what would do in the drawing was it would put it on hold and then it would spend a few clock cycles processing the mouse movement. Put that on hold and

07:15then go on to another task. It was just drawing mouse movement. Switch back and forth. So, it looks like it could handle multiple things. Say it's drawing graphics and I'm moving my mouse around. That was a goal and you're supposed to be able to do that smoothly, but it actually wasn't performing two tasks. It was simulating uh multiple tasks, but essentially time slicing. That was actually pretty tricky because you had to save the state of the operating system. Now, you don't need to know um these details for this class, but it's

07:42showing another example of where you can simulate a behavior when you're really not because those time slice are so small. it looks for all intents and purposes when you debug it that it's actually able to do two things at once.

07:55And with the early operating system, foreshadowing something that we'll probably get to, um, there were single user operating systems pre-windows and it was textbased. They shoeboarded a a graph a graphical user interface on top of this. And with a command line type interface, it's essentially one process.

08:14Your command line blocks like the UIX one where it can run things in the background. Um, when they shoehorn the graphical user interface, we've got multiple things. you've got an application loading and then you're moving the mouse around it basically simulated it. Now that will be something that operating system when they went from the U command line to the early gueies that's something we'll probably talk about assuming we get have time

08:40that's under the tech companies remote access. So this is where the connection comes in. They had something set up from Dartmouth College and he used the Got their mic here, sent some complex number equation calculation.

09:01And to put this in perspective, this was the transmission distance, the actual one, 500 kilometers or so. between the operator and the complex number calculator.

09:26However, it's hard to picture this in vision. So then I had some other things here just to and this was in New York. So it's in dark New Hampshire. This is in New York. Two different believe two different states.

09:41the operator typed it in and then within a minute it get g it shot a result back. Now to give you an idea of that distance I tried it's hard to really find something because Canada's so distributed. I picked something in Alberta something that's very close to 500 kilometers. I think I asked the eye of this one Calgary to this little town that straddles Alberta and Saskatchewan.

10:03You can look it up in some mapping system. Lloyd Minister Lloyd Minster or they give you something other landmark. Calgary to Edmonton is only about three about 300 kilometers. So traveled a fair distance and they were quite yeah this is this is pretty this is good that it could work remotely because we could put this in some safe location and have branch locations feed in the equations and it was fairly quick for the time.

10:35This only required 450 relays which was quite impressive. If you think about the relay, a relay is essentially storing one bit. Now I had a processor that had approximately a thousand gates. But a gate can it can involve more bits. It's not quite so simple. But a gate itself, well gates like and and or are more complicated than a single bit. So that

11:00they could perform the complex number calculations in real world work with only 450 relays which approximately is less than 400 far less than 450 gates was truly impressive and on top of it was a complex number calculator. my program my my architecture actually nice thing it's called digal log a program if you're really hardware oriented you can it was a free program that you could download

11:27and get in the past because it was a simulated processor it actually had a simulated assembly language and if one wanted to bother you could write assembly language programs for it but it was only a 4bit 4-bit system so it wasn't too useful as opposed to something like this which was put put to real task by the phone company.