Inside the Apple II

A detailed description of some of the tricks Steve Wozniak used inside the Apple II computer of 1977, including how he generates color graphics, the minimalist Disk II floppy drive, the 16K card, and the unusual-for-the-time switching power supply.

[@cbmeeks]

One of the best Apple II videos ever made.

[@acasualviewer5861]

Yeah, I really needed this 40 years ago.. info was very scarce

[@EvilSandwich]

You guys should watch this video because it's super informative and well done but to sum it up in a nutshell: Woz is basically Cyborg Gandalf. The end.

[@Revelator2025]

I was on the family’s Apple ][+ in 1980 when I heard from the living room that John Lennon was shot on Monday Night Football with Howard Cosell. I’ll never forget that moment. I was playing Castle Wolfenstein. 💣

[@RadosawKorzeniewski]

The lucky men who could get these manuals and books that time. I had an Apple //c without a single manual - in eastern Europe, in Poland a long time before it become democratic country. Basically no one in my town had this kind of hardware. Others had some Atari or Commodore or Sinclair at that time. I have to learn all by try and error sniffing around bits and bytes and analyzing machine code. I even wrote my own 6502 assembler and debugger to develop my own software. I could not imagine what I could develop if I had these books and manuals.

[@applemuzeumpolska]

Piękna pionierska historia!

[@acasualviewer5861]

Same here.. I had to learn Assembly language at the age of 15 with fragmented examples here and there. I guess it made me a better developer today.. but I still feel the hunger to know how this stuff worked. What was cool back then is that the system could be more fully understood back then than today's huge complex systems.

[@arrongoldberg697]

But Poland is central Europe mate. So you don’t know exactly where you are!

[@RadosawKorzeniewski]

@@arrongoldberg697 I know exactly where I live. During cold war there was no „central” part from political point of view. East part, vs. West part only. Communism vs. Democracy. I grew up on east part. Even Germany was split to west and east part. Do you remember DDR?

[@antonioruiz9923]

This is a very informative video. :)

[@wiolettabozenka9340]

Clear message, clear structure, easy to understand, thank you

[@1stSilence]

What an excellent video. I like the short on point descriptions of what made the apple II so valuable. Thank you so much for sharing!

[@Geoff160]

Brilliant! Really fantastic work.

[@fnordist]

4 days to design a floppy drive, amazing!

[@caiomar]

Exactly what I was looking for! Thank you for such great content!

[@non_maskable_interrupt]

Amazing video! Thanks for sharing the knowledge!

[@aa664_]

awesome video. nice job capturing such important history (...and explaining it so clearly ;-)

[@bb-ki3fe]

great work

[@dk418]

Great work!

[@americancitizen748]

This is excellent!

[@mr_noodler]

This video is excellent thank you for sharing your knowledge and experience for new comers like myself

[@derekchristenson5711]

Well done!

[@SU37]

brings back nice memories

[@panographic]

Wow! I learn something new every time I rewatch this video (last count: 5). I believe that Rod Holt was the designer of the Apple II's switching power supply. He was recruited by Steve Jobs while working at Atari.

[@maxxdahl6062]

Nice. I was more of a commodore 64 and IBM guy. But my aunt and uncle had Apple II that I'd play on all the time.

[@farangith]

Nostalgic video.....

[@haraldkrieger6562]

❤Woz

[@tetsujin_144]

27:25 - "Commodore drives could hold 170K, but required double-density diskettes and had a microprocessor in the drive" Unless I'm very much mistaken, there is no difference between "single-density" and "double-density" media in 5.25" disks. The difference is entirely in the drive hardware, its track/sector layout and how it encodes the data.. High density disks are a different beast (different magnetic medium, smaller, more powerful read/write head in the drive, etc.) but Apple II and Commodore machines use the same media.

[@rbrtck]

I've used a number of "single-density" disks reliably with Commodore 170K drives (such as the 1541), so I think you're right. Additionally, while the Commodore SFD-1001 supposedly requires rare quad-density (different from high-density) disks, it stores about 1MB on double-density drives just fine, as long as you use quality disks. The way Commodore did this was twofold: 1) the outer tracks have more sectors than the inner tracks, and 2) a denser form of GCR encoding is used.

[@ClausB252]

Correction: Atari 810 holds 90K per side, and it also has a microprocessor inside, a 6507.

[@Stabby666]

Great video. Your comment about the zx80 at 16:20 isn't correct though. The glitching as the keys are pressed isn't due to the CPU conflicting with the display circuitry accessing RAM. In the ZX80 the CPU draws the screen itself, and so if it's doing anything else, including reading the keyboard it causes glitches in the video output. Also, why is the outro music about 500db louder than anything else? :)

[@atomicorang]

This is completely mental!!!!

[@Starcross42]

"and to annoy your family members"

[@jmp01a24]

32:40

[@jmp01a24]

32:40 Very cool.

[@michaelblair5566]

I never owned an Apple II, I did use one in High School in the 1980's. I owned Commodore machines as a kid, a VIC 20, then a 64, then a 128.

[@rayduck6300]

At 2:41 one of the electrons turns around, goes backwards and then around another electron!

[@rbrtck]

The Apple II power supply design is nice, but watch out for those RIFA filtering capacitors!

[@0x0043]

What's the source on the video at 2:00? it's very cute.

[@stephen70edwards]

kzbin.info/www/bejne/Y5-mYYhrp9OCapY

[@snorman1911]

I had a C64 and on one hand, it blew the Apple away in regard to graphics and sound. But the Apple architecture was superior overall. The internal expansion slots were way more useful and the drive ran at light speed compared to the 1541 that was basically as slow as a tape drive.

[@carboncomplex]

c64 came out 5 years after the apple II its graphics and sound certainly should be better - the Commodore PET came out the same year as the apple II and is the comparable era commodore computer.

[@tetsujin_144]

@@carboncomplex Well the most direct comparison to the Commodore 64 would be the Apple IIe, which in some respects was a much better machine (80 column display with a modest upgrade, far better disk speed) but suffered from bearing the legacy of the aging Apple II platform. (Commodore and Apple both released machines in 1977. 5-6 years later Commodore chose to launch a new platform while Apple chose to extend their existing one. That doesn't make the IIe a 1977 machine, though, it's still a 1983 machine and it or the IIc would be the most direct competition from Apple to the Commodore 64. It was Apple's choice to not make a truly competitive home computer in the 1980s. Yes, not even the IIgs.) You know it's funny, though, about the Commodore... I owned one for years, and in my head I knew damn well just how slow those Commodore floppy drives are... And yet, I recently bought a 1581 and busted out one of my C64's to test it, and I couldn't help but be surprised at how slow it was. :) (Yes, I know it was better on the C128 with burst mode, but still...)

[@rbrtck]

They both had their strengths, but the 1541 itself wasn't a slow drive, and in fact the C64+1541 combination can load faster than the Apple II+Disk II, using only software on stock hardware. The reason the default data transfer speed of the 1541 is so slow is a long story, but it is hardly limited to that speed.

[@rbrtck]

@@carboncomplex The C64 offered more capability for the money in certain areas, for what it's worth. The retail price of the Apple II series didn't exactly plummet like those of other computers.

[@rbrtck]

@@tetsujin_144 There were some 80-column solutions for the C64, but it was never really able to escape its niche as a gaming computer, so none of them ever took off, and the C64's use as a productivity computer was limited. One problem was that Commodore's management themselves didn't view it as anything more, since at the time they also offered business-oriented computers that were developed from the PET. This was also a major reason the default 1541 data transfer speed is so slow. The designers/engineers weren't told to make it slow, and they actually tried to make it much faster than the PET and even significantly faster than the Apple II (using DOS 3.3), but there were always unfortunate last-minute technical issues, and management's decision was to not spend any money to fix the problem, since they believed that like the VIC-20, the C64 would primarily be used with cartridges and tape drives anyway. They weren't wrong about the VIC-20, but they were dead wrong about the C64. The story is a bit involved, but I guess I'll tell it anyway, in case anyone is interested. Like the Atari 8-bit series, the VIC-20 and C64 were to get a serial bus for peripherals, including disk drives. This IEC bus, which used an economical 6 wires, was intended to actually be faster than the IEEE-488 drives that the PET used. Those were very nearly as fast as the Atari drives (810 and later the 1050), but were only about half the speed of the Apple II's drives. The original IEC drive for the VIC-20, the 1540, was intended to be several or more times faster by using the 6522 VIA chip's fast hardware bit-shifter--a mode of operation that Commodore calls "burst mode". Both the VIC-20 and 1540 were equipped with VIAs for this purpose (and others), but it turned out that there was a bug in the VIA that prevented this. Many companies used the VIA (and a few still do!), which was included on a number of expansion cards for the Apple II as well, but no one was aware of this bug at the time, and time was running short until the VIC-20's planned release. Management decided to release the VIC-20 and 1540 on time rather than fix the problem, since few 1540s were expected to be sold, and the VIC-20 came with limited memory anyway, so there was only so much to load. The engineers had no time to do anything fancy, so they resorted to using a slow but reliable data transfer protocol instead. And indeed, the 1540 was a flop and the IEC was fast enough for most printing purposes, so it didn't matter. The engineers fixed the problem on the C64 and 1541 by using the similar 6526 CIA chip instead (the C64 got two of them and the 1541 got either a full or cut-down CIA in addition to its VIA chip). Then something terrible and stupid happened at the factory that was producing the first major run of C64 mainboards. The case was modified, and an additional mounting hole on the mainboard was needed right where the IEC bus lines ran. Someone at the factory decided, based perhaps on an out-of-date version of the Kernal ROM code (must have been something!), that the line in the way could simply be deleted since it supposedly wasn't needed anyway. This was the line that enabled burst mode, as it happened, and the change was made at the last second after the prior revision had been tested and approved. The result was hundreds of thousands of defective C64 main boards that were incapable of using burst mode for fast disk transfers (much faster than the Apple II). The problem could have been fixed with a simple bodge wire; many systems back in the day had multiple such fixes, after all. But Commodore's management were convinced that the 1541 was a waste of time anyway, and like the 1540 would not sell many units, so they had the engineers go back to the slow data transfer protocol (which had to be modified for the C64, by the way) and be done with it. And since the 1541 had a later release date, the CIA chip was removed from its board, which I'm sure pleased management, too. And thus, until the many fastloaders came along, the C64+1541 combination was stuck with an extremely slow data transfer rate, out of the box. Commodore still could have fixed the problem, but management had no interest in that. Their philosophy was to keep making new and incompatible computer models. The C64 could have evolved into something like the C128, which when used with the 1571 finally got the long-awaited IEC burst mode, as well as 80 columns, but instead it was made as a C64-based but incompatible computer that had a separate C64 compatibility mode. That's just not the way to do things, but it was the way of Commodore's management. That's why we got the Plus/4 and C16 (264 or TED series). On the one hand, having such variety was and is cool for general interest and history, but on the other hand, making a different computer for every perceived market segment wasn't a winning strategy, especially when it precludes existing models and series from being improved over time. The transition from the C64 to the C128 should have been like the transition from the Apple II to the Apple IIe and IIc. Instead, the C64 stagnated almost immediately, and some of its major issues weren't addressed at all, except by third-party vendors. Not that other companies were immune from this faulty way of thinking. Apple made the infamous Apple III, which failed, and the IIGS was like how Commodore went to the C128 (a different computer with a backwards compatibility mode).

[@erg0centric]

I feel old. Apple ][+, two disk drives, amber monitor, Epson MX80f/t

[@tetsujin_144]

All these crazy "gotchas" and stuff in the Apple II design... It was a great design for the late 1970s (and even decent by home computing standards into the late 1980s), but I think Apple was entirely right to start fresh with a new platform in the mid-1980s. IMO Woz was wrong about the idea of extending and expanding the Apple II to keep it relevant. The same things that made it a great system when it first came out became liabilities as the system aged.

[@tetsujin_144]

​ @Neb6 I'm not really talking about expansion cards here. I'm talking about the Apple II, a machine created in the late 1970s and based on the cheapest microprocessor available, and why it was not well-suited to growing and changing in ways that would allow it to stay relevant enough to continue to be viable more or less indefinitely, like what Apple ultimately achieved with the Macintosh platform. The Apple II was built around a lot of deep optimization of hardware and software to make it work well under those limitations. The result was actually quite a nice system, just not one that was well poised for growth IMO, especially in 1985, after the IIe and IIc had more or less cemented the platform's final form. The PC grew and changed in its first decade, and by the 1990s the de-facto limitations of the platform (especially 8086-compatibility mode, DOS, the "640K barrier", etc.) were becoming major headaches. It grew beyond those limitations essentially by becoming more of a software platform (Windows, mostly) than a hardware platform... Which is kind of exactly what Macintosh was, from the beginning.

[@mikafoxx2717]

​@@tetsujin_144the PC clones did make Intel compelled to make better and better CPU's, whereas mos that made the 6502's were owned by Commodore.. so it was complicated to make a powerful backwards compatible system. The apple iigs was a very good system think, and I'd say a better way to go forward than the Macintosh. The Macintosh line was what started almost putting apple out of business.

[@harsh9558]

How about making a 5min summary video 😃

[@JosephChiu]

so, basically trellis coding?

[@stephen70edwards]

For which, the video or the floppy? Composite video is technically QAM (Google "NTSC color modulation"); the floppy code is GCR; far simpler than trellis

[@JosephChiu]

@@stephen70edwards I just meant the self-syncing on the floppy...

[@JosephChiu]

BTW, you left out one detail in your discussion of the Disc II -- it used soft-sectors. Most floppy drives at the time used indexed sectors (hard, then soft-sectored, but indexed to the hole) -- the Disk II didn't bother. And that approach allowed for people to muck with the encoding to make copy-protection schemes possible on the Apple IIs. www.bigmessowires.com/2015/08/27/apple-ii-copy-protection/

[@stephen70edwards]

@@JosephChiu I left out many details about the Disk II. For example, I didn't say much about how it gave software direct access to the phases of the stepper motor, which ultimately allowed for truly crazy protection schemes. Even Beneath Apple DOS only begins to touch on all the nutty things people figured out how to do with it.