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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 21st Nov 2020, 1:52 pm   #1
nigelr2000
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Default Old exam paper

I have had to clear the loft ready for my bungalow to be re-roofed and found this paper in a box of stuff, bet I could only answer half or less of the questions now though I passed it with a distinction at the time. Amazing how unused knowledge just disappears
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File Type: pdf C&G Paper038.pdf (3.80 MB, 262 views)
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Old 21st Nov 2020, 2:15 pm   #2
Craig Sawyers
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Default Re: Old exam paper

Answer *all* 15 questions? I could have a decent stab at a few. When I was at university more than a decade earlier it was before the days of microprocessors - it was all mainframe stuff and punch cards. So although we did logic - as in TTL type logic - that was it.

And the general instruction was to answer four questions out of ten in the three hours. I took quite a few maths options, and one of the maths students (a petite lady) used to rattle through all ten and leave the exam early. A really smart cookie.

Happy days!

Craig
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Old 21st Nov 2020, 7:10 pm   #3
duncanlowe
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Default Re: Old exam paper

It's just a fraction after my time doing A level computer science. There's a fair bit in there that's different from what we studied, but I reckon I could have a good stab at a lot of it!
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Old 21st Nov 2020, 7:45 pm   #4
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Default Re: Old exam paper

I wouldn't bother.

After looking at some of the diagrams and the questions being asked about various blocks on them, those blocks could have operated in several different ways. Were they just tristate buffers, or were they latched? You could only do this exam after doing the relevant course because there is a lot of assumed information. The diagrams look general, but the questions will have to relate to specific processors which are not specified.

You'll find a lot of C&G stuff like this. Someone truly an expert in the field would be perplexed unable to select possible answers because he lacks the context. These exams are very much the finales of a particular course.

David
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Old 21st Nov 2020, 9:13 pm   #5
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Default Re: Old exam paper

Quote:
Originally Posted by C&G exam
Q13 Explain why, once manufactured, a dedicated microprocessor device can only be used for the purpose for which it was originally designed.
Oh yeah?
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Old 21st Nov 2020, 9:27 pm   #6
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Default Re: Old exam paper

I agree - very hard to give definitive answers. Eg
There are different ways of calculating relative addressing depending when
in the instruction the PC is incremented.

The partial instruction set matches the 6502
The partial circuit has rom at address 0 - therefore not 6502 (Stack in rom is silly)

Floppy disk diagram item D could be
Density Select sensor
Speed Select sensor
Disk Present sensor
Write protect/Write enable sensor

Divide routine - I would preset Q to 1 in step A and look for carry
after shifting Q left. But depends on how flags behave.

I would hate to mark this exam - so many different answers that could be argued to be correct.


PS - ZX80/ZX81 used the cpu as a crt controller to time character generation on a vdu! I bet it was not designed for that!
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Old 21st Nov 2020, 10:52 pm   #7
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Default Re: Old exam paper

Anyone notice that the available marks for all fifteen questions adds up to 150?
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Old 21st Nov 2020, 10:54 pm   #8
dave walsh
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Default Re: Old exam paper

This is really great although I don't grasp any of the detail? I had an interview [via the open entry scheme] at the Beeb once and could ID all the circuits but not explain them?? One chap leaned across the desk and said. "You do realise this is just a technician support job?"

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Old 21st Nov 2020, 11:02 pm   #9
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Default Re: Old exam paper

Quote:
Originally Posted by JohnBHanson View Post
I would hate to mark this exam - so many different answers that could be argued to be correct.
I'm afraid they will have marked it the easy way. They decide there is one right answer, and anything else is wrong. Nil points!

The fact that other interpretations could also be true gets ignored.

It comes from a system where a course is presented and the students must memorise it and trot it out parrot fashion to score points. Should any start to think during the process, they are headed for trouble.

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Old 22nd Nov 2020, 9:08 am   #10
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Default Re: Old exam paper

I dropped out of G&G during my apprenticeship. I found maths a struggle and there were too many distractions in my teen years. About 20 years later I applied for a day release BTEC ONC course. I enjoyed it so much I signed up for another two years to get the HNC in telecommunications. I found the BTEC learning experience to be far more interesting- very much 'hands on' with test equipment and microcomputer modules.
The canteen food was just as bad!
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Old 22nd Nov 2020, 11:13 am   #11
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Default Re: Old exam paper

I don't see any problem with it, the questions are set to reflect what was being taught on the course, like most exam questions are.

I would have managed most of those questions back in the day had I done the course, was into some of that early processor stuff back then, I remember designing a circuit and writing a program to display waveforms on a computer screen......all forgotten now.

I still have one of my old books somewhere.....Programing The Z80 by Rodney Zacks.

As someone that went through a City & Guilds course all I can say is that they did a very good job, I managed to get qualified in the art of R&TV servicing no problem and enjoyed doing all the exams so long as I had my logarithm tables with me (I was not too hot at maths...just like now)

As to where those connections are supposed to connect to, it's the same as a lot of stuff, Eg: In a TV, apart from the CRT in a TV what does the output of a video amplifier go to.....obvious answer for a pass, a not so obvious answer but technically correct would lead to a fail, but in the grand scheme of TV servicing in the real world then the obvious answer makes total sense in relation to the object of the course.

Lawrence.
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Old 22nd Nov 2020, 11:50 am   #12
Phil__G
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Quote:
Originally Posted by Avinunca View Post
I found the BTEC learning experience to be far more interesting- very much 'hands on' with test equipment and microcomputer modules.
I always tried to make BTEC fun and interesting with loads of practicals, quizzes and 'tailored tangents' to suit the class - I taught BTEC level 5 "electronics" & "microprocessor based systems" at Sheffield Poly as it was then, as well as "Telecomms Principles" for BT, thoroughly enjoyed the whole experience there are probably papers, worksheets & lesson plans up in the loft somewhere...
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Old 22nd Nov 2020, 12:43 pm   #13
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Default Re: Old exam paper

Quote:
I'm afraid they will have marked it the easy way. They decide there is one right answer, and anything else is wrong. Nil points!
I did argue that point when an exam question asked for a description of a Klystron, I described a beam Klystron and got "nil points", their argument was a reflex Klystron was taught. It took a while but I did get full marks in the end.

Back to the exam paper, I can answer all the questions with reasonable conviction that my answers are right, one of the big issues is what is a "current tracer", in my mind it's a millivolt meter so you can see which way a fault current is going.
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Old 22nd Nov 2020, 5:28 pm   #14
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I think a current tracer was some kind of magnetic pickup probe which you could align with a pcb track to see how much and which way the current was flowing along it. It would be especially useful for finding which of the many devices across a supply rail had gone short-circuit or low resistance without having to cut tracks.

I had a case several days ago where an old PCB full of soldered-in logic ICs clearly had one or more ICs short-circuit, so I could have done with one of those. I had to do it the other way - desolder the onboard 5V regulator (which was going into limit) and apply 5V power from a very heavy bench supply, ramping up the current limit until one of the chips started to get very hot.
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Old 22nd Nov 2020, 7:09 pm   #15
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Default Re: Old exam paper

HP made a pair of probes. One produced voltage spikes (scaled not to devastate TTL) and the other had a small magnetic pickup head and an edgewise pot to set sensitivity for the flashing LED display.

They worked quite well, and you could, with care follow currents in groundplanes to find shorted decouplers and dead ICs.

David
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Old 22nd Nov 2020, 9:06 pm   #16
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Default Re: Old exam paper

Quote:
Originally Posted by Radio Wrangler View Post
Quote:
Originally Posted by JohnBHanson View Post
I would hate to mark this exam - so many different answers that could be argued to be correct.
I'm afraid they will have marked it the easy way. They decide there is one right answer, and anything else is wrong. Nil points!

The fact that other interpretations could also be true gets ignored.

It comes from a system where a course is presented and the students must memorise it and trot it out parrot fashion to score points. Should any start to think during the process, they are headed for trouble.

David
AH- you mean the C & G way, where first you had to work out what the question was really asking, then work out how best to answer it.
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Old 23rd Nov 2020, 1:51 pm   #17
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Default Re: Old exam paper

To be fair, these aren't degrees. They were to judge whether or not you were safe to let loose in the workplace. Most practical education is lifetime learned, or at least honed.
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