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00:00:00,000 --> 00:00:03,060
[ The comments being read snarkily ]

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00:00:11,200 --> 00:00:12,720
...the rest of that comment was really insightful,

3
00:00:12,720 --> 00:00:13,620
thanks for sharing.

4
00:00:13,620 --> 00:00:15,380
OK, could I have been a little more clear?

5
00:00:15,500 --> 00:00:18,679
“I’ll show you Sony’s system later on,
but if you…”

6
00:00:19,120 --> 00:00:19,720
Yes.

7
00:00:19,730 --> 00:00:20,730
Yes I could have.

8
00:00:20,730 --> 00:00:26,449
But, this is in fact “later on”, so perhaps
maybe we shouldn’t jump to conclusions so quickly.

9
00:00:26,449 --> 00:00:30,359
Tell you what, I’ll work on being a little
more precise in my choice of words.

10
00:00:30,359 --> 00:00:35,650
And perhaps you, dear viewer, could refrain
from jumping to conclusions quite so quickly.

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00:00:35,650 --> 00:00:40,000
If we put our minds to it, together, we can
enhance our understanding through complex

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00:00:40,000 --> 00:00:43,960
thought both on the part of the speaker, and
on the part of the listener.

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00:00:43,960 --> 00:00:48,020
♫ And that’s how the world gets better ♫

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00:00:48,020 --> 00:00:50,440
Alright, this video is coming at you in three
parts.

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00:00:50,450 --> 00:00:51,680
As we discussed in the last video--

16
00:00:51,680 --> 00:00:53,200
NO WAIT,
wait wait wait.

17
00:00:53,200 --> 00:00:55,470
The ding was way too loud, let’s tone it
down.

18
00:00:55,470 --> 00:00:56,340
[ Ding sound from Jeopardy! ]

19
00:00:56,340 --> 00:00:57,380
Much better.

20
00:00:57,510 --> 00:01:00,760
So as we discussed in the last video, we’re
gonna take a look at some of the waveforms

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00:01:00,770 --> 00:01:05,339
coming from the components of this Magnavox
(which is really a rebadged Philips because

22
00:01:05,339 --> 00:01:08,960
Philips couldn’t use that name in the US
due to it’s passing similarity to Philco,

23
00:01:08,960 --> 00:01:11,970
I guess, but that’s a stretch) CD player.

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00:01:11,970 --> 00:01:13,530
That will be part one.

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00:01:13,530 --> 00:01:17,540
In part 2, we’ll take a look at a Sony laser
pickup and discuss the differences.

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00:01:17,540 --> 00:01:21,700
Plus I will tear this one apart to expose
the laser diode and photodiodes.

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00:01:21,700 --> 00:01:25,950
And in Part 3, we’ll discuss why Sony’s
pickup solution would become the default standard,

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00:01:25,950 --> 00:01:27,740
used to this day in optical drives.

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00:01:27,740 --> 00:01:29,670
We’ll begin with Part 1.

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00:01:29,670 --> 00:01:32,600
And Part 1 will be quite a bit different from
most other videos.

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That’s because much of it is unscripted.

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00:01:35,370 --> 00:01:36,430
Off the cuff.

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00:01:36,430 --> 00:01:37,580
Just gonna wing it.

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Yeah.

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But first, a few corrections.

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00:01:39,640 --> 00:01:43,620
As usual, the Internet has provided answers
that I did not find, and has revealed some

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00:01:43,620 --> 00:01:46,570
mistakes and false assumption from the last
video.

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Of course.

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00:01:47,570 --> 00:01:51,210
But that’s OK, we all make mistakes, and
now I’m gonna tell you what we learned thanks

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00:01:51,210 --> 00:01:54,600
to the diligent research of more knowledgeable
people than me.

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00:01:54,600 --> 00:01:56,420
Remember it’s OK to not know everything.

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00:01:56,420 --> 00:01:59,340
And it’s OK to ask for advice from professionals.

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00:01:59,340 --> 00:02:00,220
♫ And that’s h--♫

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00:02:00,220 --> 00:02:04,119
Let me reveal the most dumb mistake, and it
was right on screen.

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00:02:04,119 --> 00:02:06,690
The best kind of mistake.

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00:02:06,690 --> 00:02:11,090
I had been assuming that pin 10 was the output
signal from the focus chip, and that it would

47
00:02:11,090 --> 00:02:13,260
be a binary stream from the pits and lands.

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00:02:13,260 --> 00:02:15,440
Boy was that wrong on many counts.

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00:02:15,440 --> 00:02:18,769
First, it’s not pin 10 that does that, it’s
pin 3.

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00:02:18,769 --> 00:02:21,560
And it’s labeled right here on the datasheet.

51
00:02:21,560 --> 00:02:26,330
Pin 3 is also labeled to decoder, which I
missed, and most importantly it’s a sum

52
00:02:26,330 --> 00:02:30,610
of the outputs from all 4 photodiodes as illustrated
right here.

53
00:02:30,610 --> 00:02:35,980
Yes pin 10 also gets the sum of the 4 diodes,
but unlike pin 10, pin three has an amplifier,

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00:02:35,980 --> 00:02:38,879
equalizer, and another amplifier to boost
the output.

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00:02:38,879 --> 00:02:39,980
Hm hmmm.

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00:02:39,980 --> 00:02:45,029
I want to give a big thanks and shoutout to
Zim0256 who not only created the helpful diagram

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00:02:45,029 --> 00:02:50,230
that I used on a few occasions but who also
gave more complete info on what is going on.

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The Motorola processor is a custom chip based
around an HC08 microcontroller, and it is

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00:02:55,569 --> 00:02:58,769
in fact the decoder that is doing most of
the work.

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00:02:58,769 --> 00:03:03,019
I couldn’t find its datasheet because the
P on the end was limiting my search results.

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00:03:03,019 --> 00:03:06,180
And to think, we just learned about minding
our p’s and q’s.

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00:03:06,180 --> 00:03:10,379
Anyway, in fact the decoder is handling all
the raw data; undoing the eight-to-fourteen

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00:03:10,379 --> 00:03:12,970
modulation, isolating the subcode, and all
that.

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00:03:12,970 --> 00:03:17,069
It even digitizes the output from pin 3, which
at this point is still analog which we’ll

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00:03:17,069 --> 00:03:18,180
see in a moment.

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00:03:18,180 --> 00:03:22,670
It sends the extracted subcode to the processor
so it knows how to handle the disc and respond

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00:03:22,670 --> 00:03:23,829
to user requests.

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00:03:23,829 --> 00:03:28,040
Really, the processor is just managing the
living and breathing tasks of the machine,

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00:03:28,040 --> 00:03:31,859
such as the user interface, display, and other
goodies like popping the disc tray in and

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00:03:31,859 --> 00:03:34,059
out and getting the whole process going.

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00:03:34,059 --> 00:03:37,939
Speaking of the disc tray, a few people had
asked how the machine can tell that the disc

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00:03:37,939 --> 00:03:42,959
tray has been pushed in manually as opposed
to someone hitting the open/close button.

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Some other people noticed this strange button
switch near the decoder.

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00:03:47,120 --> 00:03:49,969
These two groups of people are discussing
the same thing.

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00:03:49,969 --> 00:03:53,879
To the right of the disc tray is a little
series of levers that rest on top of this

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00:03:53,879 --> 00:03:56,329
button when it’s assembled.

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Little nubs on the bottom of the tray will
cause this to push down on the button in either

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00:04:00,529 --> 00:04:02,870
the open or closed position.

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00:04:02,870 --> 00:04:06,459
This not only tells the processor that the
tray has reached the end of its travel in

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00:04:06,459 --> 00:04:10,560
either direction, but it also means that it
can detect if the tray has been pushed in,

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00:04:10,560 --> 00:04:14,730
as the button will be released (and thus the
switch opened) as soon as the tray is moved

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00:04:14,730 --> 00:04:15,829
out of its open position.

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00:04:15,829 --> 00:04:18,329
OK, it’s time for the script to be put to
the side.

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00:04:18,329 --> 00:04:22,310
I’ve got a sort of odd setup here, because
I need to see both the oscilloscope screen

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00:04:22,310 --> 00:04:26,930
and what I’m poking on the board, so we’re
gonna do some picture-in-picture editing magic

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00:04:26,930 --> 00:04:29,069
and throw the scope screen up high.

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00:04:29,069 --> 00:04:30,069
Excellent!

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00:04:30,069 --> 00:04:35,100
And you know what, maybe we’ll throw another
camera up here so you can see what I’m doing.

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00:04:35,100 --> 00:04:35,820
Even better.

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00:04:35,820 --> 00:04:36,640
All the cameras!

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00:04:36,640 --> 00:04:37,820
All the tripods!

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00:04:38,260 --> 00:04:40,620
Well this is… awkward.

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00:04:40,620 --> 00:04:42,680
It’ll have to do.

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00:04:42,680 --> 00:04:45,169
As promised, we’re gonna poke around on
some of the things here!

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00:04:45,169 --> 00:04:49,639
Now I brought my laptop here so I can actually
go and look and see what I’m looking at,

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00:04:49,639 --> 00:04:54,110
and you’ll notice these, uh, wires that
I’ve soldered onto chips underneath.

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00:04:54,110 --> 00:04:56,180
I’ll bring up the image of that.

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00:04:56,180 --> 00:05:00,430
Part of the issue with this player is that
it has to be--the ribbon cable between the

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00:05:00,430 --> 00:05:05,560
drive and the board is very very short, and
there’s pretty much no way to operate this

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00:05:05,560 --> 00:05:06,580
unless it’s assembled.

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00:05:06,580 --> 00:05:10,990
I really don’t know how people would service
these things, ‘cause it, ya know… a lot

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00:05:10,990 --> 00:05:16,830
of the… a lot of the stuff that I wanna
see is underneath the CD reader like the,

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00:05:16,830 --> 00:05:20,069
uh, the tracking and focus chips are basically
directly under here.

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00:05:20,069 --> 00:05:22,050
That’s not helpful.

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00:05:22,050 --> 00:05:25,870
But we can see what else we can take a look
at.

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00:05:25,870 --> 00:05:32,600
I did find, just from poking--at one point
I found the raw datastream.

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I think it was one of these guys.

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Unfortun… what is happening here?

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00:05:39,620 --> 00:05:40,200
Oh.

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00:05:44,960 --> 00:05:48,259
Well this is kind of interesting, what’s…
uh I wonder what’s on this line, let’s

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00:05:48,260 --> 00:05:49,900
see if I can figure it out.

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00:05:49,900 --> 00:05:54,380
Notice that we’re on a really long time
scale.

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I think this is the subcode.

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If I can hopefully… get the... trigger…

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00:05:59,990 --> 00:06:00,990
I’m...eurgh…

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00:06:00,990 --> 00:06:04,129
I’m really...have no experience with a scope.

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00:06:04,129 --> 00:06:05,139
So, just.

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00:06:05,140 --> 00:06:06,460
Just so ya know.

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00:06:07,460 --> 00:06:09,360
Let’s try…

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00:06:09,360 --> 00:06:10,379
Oops that’s what I meant.

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That’s what I meant!

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The other way…

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00:06:12,640 --> 00:06:13,140
Oh!

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00:06:13,140 --> 00:06:14,140
It’s probably you, OK.

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Yep, OK.

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00:06:16,600 --> 00:06:17,520
Ha ha!

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00:06:17,520 --> 00:06:18,520
I found it!

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00:06:18,530 --> 00:06:25,530
So this here is the waveform that’s coming
from the amplifier chip from the au, from

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00:06:25,530 --> 00:06:28,800
uh the TDA8808T augh that one, that one.

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00:06:28,800 --> 00:06:35,229
So this, this is the amplified output of the…
oops, of the pits and lands.

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00:06:35,229 --> 00:06:39,949
So this is the raw analog signal coming from
the disc.

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And if we look a little closer… you can
see if I touch the disc… see how that’s…

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00:06:49,500 --> 00:06:50,680
Oh. Well I’ve killed it.

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00:06:51,120 --> 00:06:52,120
Great.

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00:06:52,280 --> 00:06:53,840
Great job!

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00:06:53,840 --> 00:06:57,940
So if I kinda just touch it you can see the--it
slows down a bit.

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00:06:58,600 --> 00:06:59,980
Let me zoom out a bit.

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00:06:59,980 --> 00:07:02,900
Oop--zoom out a bit.

139
00:07:04,660 --> 00:07:06,259
See that?

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00:07:07,560 --> 00:07:10,120
It just completely--it gave up there.

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00:07:10,120 --> 00:07:16,200
That click sound you heard I believe is the
laser kicking up all the way.

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00:07:19,260 --> 00:07:23,060
But yeah so this--this isn’t the raw output
from the photodiodes but this is the amplified

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00:07:23,060 --> 00:07:26,979
output coming from pin 3, going to the decoder.

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00:07:26,979 --> 00:07:34,280
The output from the photodiodes is very very
small, this is… if we take a look and compare

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00:07:34,280 --> 00:07:36,520
the voltage level there’s almost nothing
there.

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00:07:37,140 --> 00:07:39,900
And it’s so noisy I can’t see anything.

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00:07:39,900 --> 00:07:45,319
These all should be the same.

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00:07:46,680 --> 00:07:49,840
There’s nothing there.

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00:07:49,849 --> 00:07:52,789
Which is a shame because I really wanted to
show you that!

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00:07:52,789 --> 00:07:54,680
Oh well.

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00:07:56,020 --> 00:08:00,080
Wanted to show you some interesting stuff,
and I think that we saw some interesting things

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00:08:00,080 --> 00:08:03,550
but not as many as I was hoping.

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00:08:03,550 --> 00:08:06,969
Well, with that disappointing segment out
of the way, let’s move on to the part that

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I didn’t forget about.

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00:08:08,009 --> 00:08:12,180
To see how Sony handled the optical system
differently, we need to get our hands on a

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00:08:12,180 --> 00:08:15,949
Sony CD player, hopefully of similar vintage
to this Philips one.

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00:08:15,949 --> 00:08:20,129
Oh perfect, a Sony CD changer from 1992!

158
00:08:20,129 --> 00:08:23,819
Now it doesn’t really matter that it’s
a changer, there’s still a standard CD mechanism

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00:08:23,819 --> 00:08:28,219
in here, it’s just on a pivot and will happily
pop up and fall down to greet or say farewell

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00:08:28,219 --> 00:08:30,060
to the disc it plays.

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00:08:30,060 --> 00:08:34,570
It works in tandem with the disc tray, which
rather than just being an inny-outty operation,

162
00:08:34,570 --> 00:08:37,400
it’s an inny-outty with rotational flair.

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00:08:37,400 --> 00:08:42,450
Now I embarked on the frightening task of
getting this mechanism out of this player.

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00:08:42,450 --> 00:08:47,480
Armed only with an ordinary screwdriver, I
went hamfisted and started unscrewing stuff,

165
00:08:47,480 --> 00:08:52,840
before I realized I hadn’t filmed the close
up segments of the laser tracking a disc.

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00:08:52,840 --> 00:08:55,700
After undoing what I had begun, I began once
more.

167
00:08:55,710 --> 00:08:57,040
The screws are the enemy!

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00:08:57,040 --> 00:08:58,040
Be gone!

169
00:08:58,040 --> 00:09:02,620
Or, be twisted counterclockwise sufficiently
until such time that they can be gone!

170
00:09:02,620 --> 00:09:07,500
Having gained unrestricted access to our prize,
I loosened the four screws holding it in place.

171
00:09:07,500 --> 00:09:09,120
But it wouldn’t budge.

172
00:09:09,120 --> 00:09:13,680
Yet more screws needed liberation, until finally
I had successfully removed the crown jewel

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00:09:13,680 --> 00:09:15,960
from the temple of forbidden technology.

174
00:09:15,960 --> 00:09:17,600
And, uh, here it is.

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00:09:17,600 --> 00:09:21,520
One of the big differences you’ll see between
this and the Philips mechanism is everything

176
00:09:21,520 --> 00:09:23,360
is much more integrated.

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00:09:23,360 --> 00:09:27,780
In fact this one chip here, if the datasheet
I found is at all correct (link below) has

178
00:09:27,780 --> 00:09:33,120
32 k of RAM built in, does the EFM demodulation
as well as the CIRC error correction, handles

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00:09:33,120 --> 00:09:37,870
the focus, tracking, and spindle motor (using
this chip as a driver to handle the power),

180
00:09:37,870 --> 00:09:41,870
extracts the subcode, provides a data output
for the DAC, and can even do such exotic things

181
00:09:41,870 --> 00:09:46,120
as double-speed playback and variable pitch
playback (assuming the player it’s inside

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00:09:46,120 --> 00:09:48,020
has those functions enabled).

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00:09:48,020 --> 00:09:49,450
Did I mention it’s bilingual?

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00:09:49,450 --> 00:09:53,470
It’s interesting how just 4 years time managed
to integrate functions that are spread out

185
00:09:53,470 --> 00:09:58,030
via multiple chips on this Philips machine
into just this one chip on the board of the

186
00:09:58,030 --> 00:09:59,440
laser pickup.

187
00:09:59,440 --> 00:10:00,870
But that makes a lot of sense.

188
00:10:00,870 --> 00:10:04,480
See, this Philips board only works with
one mechanism.

189
00:10:04,480 --> 00:10:08,560
Because its driver components are part of
the main board design, anything but a Philips

190
00:10:08,560 --> 00:10:13,000
CDM4 pickup won’t work without at least
some modification.

191
00:10:13,000 --> 00:10:17,280
But for the Sony machine, this ribbon cable
is essentially just proving a power, ground,

192
00:10:17,280 --> 00:10:21,180
a communication bus to the CPU, and a datastream
for the DAC.

193
00:10:21,180 --> 00:10:25,530
This component can be completely redesigned,
and so long as it accepts the same inputs

194
00:10:25,530 --> 00:10:29,710
and produce the same outputs, the main board
really won’t care.

195
00:10:29,710 --> 00:10:33,730
This allows Sony to make production improvements
and even radical changes to this mechanism

196
00:10:33,730 --> 00:10:36,220
and how it works without disturbing the main
board.

197
00:10:36,220 --> 00:10:40,010
You can see how Sony played a modular approach
via the markings on the board.

198
00:10:40,010 --> 00:10:43,620
This one board was used in many different
players, with different components marked

199
00:10:43,620 --> 00:10:45,600
“FOR X player only”.

200
00:10:45,600 --> 00:10:48,290
By my count it was used in at least 5 players.

201
00:10:48,290 --> 00:10:51,650
Really, Sony’s markings are just a lot more
helpful.

202
00:10:51,650 --> 00:10:53,580
Wondering which one of these is the DAC?

203
00:10:53,580 --> 00:10:55,660
Hey look, it’s labeled right here.

204
00:10:55,660 --> 00:10:58,010
And you’ll find a PULSE chip on the bottom.

205
00:10:58,010 --> 00:11:01,430
I’m pretty sure these are 1-bit DACs, based
on some vague research.

206
00:11:01,430 --> 00:11:04,720
I’m sure someone will correct me if I’m
wrong, and I’m counting on it.

207
00:11:04,720 --> 00:11:07,940
And the fact that they’ve labeled these
jumper connections on the top of the board

208
00:11:07,940 --> 00:11:10,690
for what they are sure is helpful.

209
00:11:10,690 --> 00:11:11,640
That would’ve been nice,

210
00:11:11,640 --> 00:11:12,320
PHILIPS.

211
00:11:12,320 --> 00:11:15,120
Anyway, back to the laser because that’s
the real difference.

212
00:11:15,120 --> 00:11:17,030
First, gone is the swing-arm.

213
00:11:17,030 --> 00:11:21,880
Instead, the laser is mounted on a sled, which
moves linearly with the help of this rack

214
00:11:21,880 --> 00:11:23,270
and pinion drive.

215
00:11:23,270 --> 00:11:28,270
Now, you might suspect that this drive arrangement
does not have the precision to track the disc.

216
00:11:28,270 --> 00:11:32,090
The floating arm of the Philips system means
it can move subtly and precisely to track

217
00:11:32,090 --> 00:11:33,400
an off-center disc.

218
00:11:33,400 --> 00:11:37,920
But this brutal, inelegant plastic gear train
can’t possibly be used for the tracking.

219
00:11:37,920 --> 00:11:38,820
And it isn’t.

220
00:11:38,820 --> 00:11:42,640
Just like the Philips system, this lens is
floating and can move up and down.

221
00:11:42,650 --> 00:11:47,170
But unlike the philips system, this lens can
also move left and right.

222
00:11:47,170 --> 00:11:50,720
With the help of a diode I have laying around,
you can see that the laser can move quite

223
00:11:50,720 --> 00:11:52,230
a bit to either side.

224
00:11:52,230 --> 00:11:55,150
Let’s take off this plastic shroud to get
a better look.

225
00:11:55,150 --> 00:11:57,600
Ah this one is perfect for showing this.

226
00:11:57,600 --> 00:11:58,600
Yes.

227
00:11:58,600 --> 00:12:03,250
OK, I’m sure you can see these rectangular
coils surrounding a vertical structure.

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These coils will push the lens upward if a
voltage is passed through them.

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But if you look very carefully, you’ll also
see a pair of circular coils on the outer edges.

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When a voltage is applied to these, depending
on the polarity it will attract itself to

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these handy magnets placed on the sides, or
it will push itself away.

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This causes the lens to pivot either left
or right, depending on which way you slice it.

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The best part of this setup is that the lens
is completely independent of the sled that

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it’s riding on.

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If the sled moves a bit, it doesn’t care--it
will just react to that movement as though

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the track of pits it’s... tracking has moved
slightly.

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That means that the sled only has to move
in coarse steps, and the lens will take care

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of the rest.

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But that’s just one significant difference.

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The other is in the photodiode arrangement.

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You may have seen the term

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THREE-BEAM LASER
TRACKING

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before.  Or something like that.

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In these systems, rather than using only four
photodiodes like in the Philips system, we

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use six.

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In the middle are four cells arranged…

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actually
exactly like the Philips system.

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These are used in an identical fashion for
focus--an elliptical reflection indicates

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an out-of-focus beam, and its orientation
indicates if focus is near or far.

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But to correct tracking errors, two additional
diodes to either side are monitoring for an

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off-center beam.

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In these systems, a diffraction grating splits
the laser beam into three.

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In reality it splits it into infinite beams
of increasingly weak intensity as they deviate

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from the center but we only care about the
center beam and the two immediately surrounding it.

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Now, when tracked correctly, the outside beams
shouldn’t land on the stream of pits.

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They should instead land just outside of them,
which will thus cause them to reflect the

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featureless boundaries.

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The reason this works to track the stream
is that if the track deviates, suddenly one

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of the tracking diodes will start seeing the
datastream.

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That’s not supposed to happen, so the player
will react by nudging the lens in the direction

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00:13:48,810 --> 00:13:50,890
of the activated tracking diode.

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This system is certainly more complex on the
hardware side, but given how simple the trigger

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is--no need to compare ratios, simply see
if a single thing is happening--it’s probably

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a lot easier to implement.

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However, this make me wonder if this system
is fundamentally worse at tracking discs.

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See, I’ve heard anecdotal evidence that
the original Philips single-beam tracking

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is superior at tracking scratched or damaged
discs.

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And with the knowledge of how the three-beam
tracking works, that kind of makes sense.

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Imagine a scratch appears just next to the
datastream.

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00:14:22,630 --> 00:14:26,950
If that scratch is bad enough, it might bend
one of the tracking beams towards the raw

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00:14:26,950 --> 00:14:31,570
datastream, causing the lens to deflect for
a defect that isn’t really there.

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00:14:31,570 --> 00:14:36,180
With the Philips system, it wouldn’t see
this scratch because it only has the one scanning beam.

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It would ignore it and thus be unaffected.

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00:14:38,200 --> 00:14:41,900
Now of course, these conventional systems
aren’t remarkably inferior.

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They can tolerate scratches pretty well, too.

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00:14:43,730 --> 00:14:48,890
But it makes me wonder if there is truth to
the anecdote that the swing-arm servo, Philips

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00:14:48,890 --> 00:14:51,730
single beam tracking whatever is indeed superior.

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One last thing before we answer why this became
the standard.

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I’m not afraid to tear this apart and find
what inside.

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So first, you can see the actual laser diode
here as opposed to the Philips machine where

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its housed in this plastic.

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This, like in the Philips setup, projects
the light sideways where it hits a prism,

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00:15:08,140 --> 00:15:12,700
get shot up at the disc surface (which the
floating lens helps to keep tracked and focused)

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00:15:12,700 --> 00:15:16,130
and it gets reflected back, goes straight
through the prism, and lands on this little

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00:15:16,130 --> 00:15:17,580
chip here.

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00:15:17,580 --> 00:15:21,860
Now this is interesting, because on this machine
we can actually see the backside of the photodiode

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00:15:21,860 --> 00:15:25,840
array, unlike on the Philips machine where
we could only see the board.

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00:15:25,840 --> 00:15:30,440
If I keep going to remove the lens and get
everything apart, you can see the prism in here.

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00:15:30,440 --> 00:15:34,420
Take a look, it does a great job of reflecting
light at a 90 degree angle.

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00:15:34,420 --> 00:15:36,880
And now, let’s see what we can see of the
photodiodes.

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Well, don’t get your hopes up--they are
pretty much microscopic.

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00:15:40,680 --> 00:15:44,940
To be fair, we are dealing with laser light
focused on microscopic pits, so its

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00:15:44,940 --> 00:15:47,440
stands to reason that these are probably pretty
small.

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00:15:47,440 --> 00:15:49,340
I don’t have a microscope handy

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00:15:49,340 --> 00:15:50,140
--yet--

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00:15:50,140 --> 00:15:52,920
but I do have my ridiculous macro lens setup so

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00:15:52,930 --> 00:15:55,380
I could get these extreme closeups.

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00:15:55,380 --> 00:15:59,840
You can definitely see that these are three
clusters, with one used for data capture and

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00:15:59,840 --> 00:16:03,330
focus control, and the two to either side
for tracking.

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00:16:03,330 --> 00:16:07,230
To show how small this is, I’ve placed a
dime next to it for scale.

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00:16:07,230 --> 00:16:10,750
For a more International perspective, how
about a micro SD card?

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00:16:10,750 --> 00:16:13,720
And just for fun, here’s the point of a
safety pin.

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These really are tiny.

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00:16:15,270 --> 00:16:19,510
So now, why did Sony’s floating lens and
stepping platform become the de facto method

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00:16:19,510 --> 00:16:21,430
of reading optical discs?

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00:16:21,430 --> 00:16:26,650
With more photodiodes and greater mechanical
complexity, you might think it to be inefficient.

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00:16:26,650 --> 00:16:31,720
Well it may be inefficient in some ways, but
in most ways it’s in fact much more efficient.

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00:16:31,720 --> 00:16:34,170
First, let’s take size.

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00:16:34,170 --> 00:16:38,020
If we look at the Philips system, you’ll
notice that the entire laser pickup is essentially

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00:16:38,020 --> 00:16:39,930
behind the disc.

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00:16:39,930 --> 00:16:44,400
The pivot point for the swing arm has to be
farther to the rear of the player, otherwise

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00:16:44,400 --> 00:16:49,100
it would simply rotate around the circumference
of the disc, and that wouldn’t be very helpful.

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00:16:49,100 --> 00:16:52,420
This off the bat limited its potential to
miniaturize.

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00:16:52,420 --> 00:16:55,020
And boy, did this get smaller quickly.

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00:16:55,020 --> 00:16:57,720
Portable CD players burst on the scene in
1984.

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00:16:57,730 --> 00:17:01,880
And they would only continue to get smaller,
with one CD player featured by Techmoan actually

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00:17:01,880 --> 00:17:04,240
being smaller than a CD.

318
00:17:04,240 --> 00:17:08,209
And that was in 1988, the same year as this
Philips machine was made!

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00:17:08,209 --> 00:17:11,470
In fact, this very mechanism is larger than
it needs to be.

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00:17:11,470 --> 00:17:16,370
If these parts were shifted downward, it could
be no longer than the distance here.

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00:17:16,370 --> 00:17:18,440
And this laser platform could get smaller.

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00:17:18,540 --> 00:17:19,160
And smaller.

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00:17:19,340 --> 00:17:19,840
And smaller.

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00:17:20,260 --> 00:17:25,380
Until eventually you’re into modern slim
drives for PCs which have the tiniest of lenses

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00:17:25,380 --> 00:17:27,220
and thinnest of assemblies.

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00:17:27,220 --> 00:17:32,150
And the PC market would only continue to make
this Philips system harder to justify.

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00:17:32,150 --> 00:17:37,130
In fact, one fatal flaw of the Philips reader
would make sure it fizzled into obscurity:

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00:17:37,130 --> 00:17:38,250
its mass.

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00:17:38,250 --> 00:17:42,070
Imagine in a portable player, which can be
set in any position, or even moved around

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00:17:42,070 --> 00:17:45,440
while playing, that it had this swinging laser
pickup.

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00:17:45,440 --> 00:17:50,130
It’s so loosey-goosey that it’s doubtful
it will track very well.

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00:17:50,130 --> 00:17:53,270
And its mass also limits how quickly it can
move.

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00:17:53,270 --> 00:17:58,290
When CD-ROM drives appeared, and getting faster
and faster and faster, the laser would have

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00:17:58,290 --> 00:18:02,910
to be able to wiggle itself back and forth
at frequencies in excess of 10 kilohertz.

335
00:18:02,910 --> 00:18:06,780
That’s easy if you’re just wiggling at
small piece of plastic back and forth, but

336
00:18:06,780 --> 00:18:10,320
a lot harder if you’re wiggling this big
swinging thing.

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00:18:10,320 --> 00:18:14,940
And so, Sony’s three-beam laser tracking
would be miniaturized and improved over the years.

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00:18:14,940 --> 00:18:19,260
Developments in anti-skip functionality meant
that CD walkmen could be tossed around without

339
00:18:19,260 --> 00:18:23,530
fear of skipping or glitches, or getting stuck
repeating a bit of the track.

340
00:18:23,530 --> 00:18:27,780
That was accomplished simply by reading the
disc at faster than normal speeds, creating

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00:18:27,780 --> 00:18:31,860
an intermediary data buffer between the disc
and the processor.

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00:18:31,860 --> 00:18:35,970
The DAC could have upwards of 40 seconds at
its disposal for the laser to get back on

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00:18:35,970 --> 00:18:37,820
track and resume the datastream.

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00:18:37,820 --> 00:18:42,620
Which, thanks to the timecode, is easy to
piece together if a problem does arise, thus

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00:18:42,620 --> 00:18:44,740
eliminating the effects of skipping.

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00:18:44,740 --> 00:18:48,700
And of course, later on the wavelength of
light would change to red, packing the pits

347
00:18:48,700 --> 00:18:52,680
closer together and creating the MUSE high
definition laserdisc.

348
00:18:52,680 --> 00:18:56,680
And then later the DVD, an obscure digital
video format you might have heard of.

349
00:18:56,680 --> 00:19:01,240
Later we’d say, enough with the red, in
with the blue and we’d be packing upwards

350
00:19:01,250 --> 00:19:06,650
of 25 gigabytes onto a slightly different
silver plastic thing, after we briefly reenacted

351
00:19:06,650 --> 00:19:09,180
the videotape format wars of the 1980’s.

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00:19:09,180 --> 00:19:10,180
Because why not.

353
00:19:10,380 --> 00:19:11,860
But we’re getting ahead of ourselves.

354
00:19:11,860 --> 00:19:13,780
There’s lots more to talk about.

355
00:19:13,780 --> 00:19:18,270
When we next check in on optical disc technology,
we’ll discuss the Yellow Book, the standard

356
00:19:18,270 --> 00:19:22,210
published in 1988 that defines the specifications
of the CD-ROM.

357
00:19:22,210 --> 00:19:27,820
Then we’ll talk about some writable disc
technologies like CD-R and CD-RW, and then,

358
00:19:27,820 --> 00:19:31,990
if interests persists, we might dig a little
deeper into the DVD and some of the follies

359
00:19:31,990 --> 00:19:33,450
of its development.

360
00:19:33,450 --> 00:19:39,430
Such as how this logo mysteriously features
a disc for a solid state memory format.

361
00:19:39,430 --> 00:19:40,430
Hmm.

362
00:19:40,430 --> 00:19:43,010
Thanks for watching, I hope you enjoyed the
video!

363
00:19:43,010 --> 00:19:46,250
If you missed the first two videos on the
Compact Disc, you can check them out in the

364
00:19:46,250 --> 00:19:49,740
playlist on Digital Sound that will quietly
pop up above me.

365
00:19:50,020 --> 00:19:51,760
So serene.

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00:19:52,060 --> 00:19:55,900
As always, a great big thank you to every
who supports this channel on Patreon, especially

367
00:19:55,910 --> 00:19:58,720
the fine folks that are scrolling up your
screen.

368
00:19:58,720 --> 00:20:02,400
If you’re interested in pledging some support
to the channel to help it grow, please check

369
00:20:02,400 --> 00:20:03,670
out my Patreon page.

370
00:20:03,670 --> 00:20:06,160
Thanks for your consideration, and I’ll
see you next time!

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00:20:06,340 --> 00:20:08,060
[ everyone’s favorite, gloriously tacky
music plays ]

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00:20:08,640 --> 00:20:13,540
Hey one thing, my most viral video to date
was about how Sony used the tracking servos

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00:20:13,550 --> 00:20:18,230
in a CD player to create the copy protection
scheme in the original Playstation.

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00:20:18,230 --> 00:20:22,270
You might want to check that video out, but
be warned that there are a number of annoying

375
00:20:22,270 --> 00:20:25,470
things about the flow of information over
there.

376
00:20:25,470 --> 00:20:29,440
It goes into a lot of detail about the PlayStation
and some of its history, and the comments

377
00:20:29,440 --> 00:20:35,480
on there (if you dare to look at them) indicate
that many people were… not happy about it.

378
00:20:35,480 --> 00:20:38,720
So if you haven’t seen it, check it out,
and apologies in advance.

379
00:20:38,720 --> 00:20:40,860
Ha, and another thing!

380
00:20:40,860 --> 00:20:44,950
So if you didn’t know, there’s a second
channel - Technology Connections 2 - where

381
00:20:44,950 --> 00:20:47,750
I upload weird stuff from time to time.

382
00:20:47,750 --> 00:20:52,559
And I just uploaded a video of a couple of
CD players that are very similar but have

383
00:20:52,559 --> 00:20:53,559
some unique differences.

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00:20:53,560 --> 00:20:57,860
So if you want to check if out, please feel
free to click the link down below or up above.