Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Apple Disk II Controller Card (2021)

bigmessowires.com

Post reply on HN
Print view View original

21–28 of 28 posts

Re: The Apple Disk II Controller Card (2021)

#21

Post by talideon »

cameldrv wrote: post #12
dboreham wrote: post #4

Earlier quoted context omitted.

Commodore disk drives (4040 and so on) actually use a very similar approach. There's no FDC controller chip and the 6502 is hooked to the drive (literally the same SA-390 as Apple used) via simple hardware. The only significant difference is that the 6502 (actually two of them) is in a separate enclosure from the Pet , communicating via IEEE-488. Since Commodore manufactured the 6502 presumably it was ok to use them…

They were really slow though. It took minutes to boot up a game from the 1541. I never had one but my friends did, and one of them had a "Fast Load Cartridge", which I believe just replaced the software on the drive and on the computer with better software that was something like 5x as fast.

It wasn't really the hardware's fault though. It was crippled by Commodore's marketing department wanting to maintain compatibility with the VIC-20's 1540 FDD, which meant that the bit banging method used to work around a bug in the VIA chip had to be used. Then to add insult to injury, because of how the VIC-II and 6510 need to share the bus, it ended up running even slower than the VIC-20.

Re: The Apple Disk II Controller Card (2021)

#22

Post by ezekiel68 »

TMWNN wrote: post #16
cameldrv wrote: post #12

Earlier quoted context omitted.

They were really slow though. It took minutes to boot up a game from the 1541. I never had one but my friends did, and one of them had a "Fast Load Cartridge", which I believe just replaced the software on the drive and on the computer with better software that was something like 5x as fast.

>that was something like 5x as fast. ... which is still significantly slower than the Disk II. The 1978 Disk II is about 30 times faster than the unaccelerated 1982 Commodore 1540/1541, as well as more reliable,[1] cooler-running,[2] and just more elegantly designed. The same comparison holds for the 4040 and other pre-1541 Commodore drives, albeit with the speed disadvantage vis-a-vis Apple being less.[3] [1] The 15…

I'm sure all of this is "correct", but the fact is that many of us (myself included) enjoyed years of trouble-free service from our Commodore 1541 disk drives. And we could easily compare them with the Apple ][ computers and drives we learned on at high school

Re: The Apple Disk II Controller Card (2021)

#23

Post by alnwlsn »

TMWNN wrote: post #3

As zellyn said, Disk II is pure genius writ large. It's flabbergasting how good Woz's designs were. Almost on a whim, he with the Disk II did something no one anywhere in Silicon Valley—anywhere in the world —was doing. Forget about IBM, HP, Shugart, Tandon. Just within Commodore and Tandy, Apple's direct 1977 competitors, there were abundant human and engineering resources to come up with a fast, inexpensive, and re…

I mean, in 1978 Tandy used standard drives and a disk controller IC, and still managed to sell a whole 16K TRS-80 system with disk drive for the same price (TRS-80 Level II 16K + Expansion Interface + disk drive = $1786 [0]) as Apple (Apple II + Disk II + drive = $1790 [1]). Plus, the TRS-80 came with a video monitor wheras Apple did not. But the Disk II could hold more data per disk, and I'm sure Apple's margins were better.

0 - https://ia803203.us.archive.org/9/items/Radio_Shack_TRS-80_S...

1 - http://www.apple-iigs.info/doc/fichiers/Apple%20Price%20List...

Re: The Apple Disk II Controller Card (2021)

#24

Post by ralferoo »

Lots of people are commenting on how unique it was to have a software based disk interface instead of stand alone hardware. And in a sense that is true, but also not.

Around that time there were various iterations of floppy controllers, each having a small microprocessor at their core. Just before the Apple Disk II, NEC released the uPD765 which is contains everything needed in one chip, but actually it's mostly just a small microprocessor taking a very similar approach under the hood in terms of track decoding. In fact the uPD in the part name is a giveaway that the implementation is a microprocessor instead of logic gates (and the command and reply interface). That operates a lot more like the Commodore drive, except it has a parallel interface with the host processor instead of a serial interface.

Sadly, I don't know anybody who's attempted to extract the ROM out of that microprocessor and reverse engineer it, but I'd definitely be fascinated to see that for faithful emulation purposes (at least for my emulator, I just implemented the interface as described in the datasheet).

Re: The Apple Disk II Controller Card (2021)

#25

Post by dhosek »

stmw wrote: post #9
dhosek wrote: post #7

The great thing about the whole Apple ][ system was that it was sophisticated enough to actually do stuff but simple enough that a single person could understand it (largely because it was mostly the work of a single person). To this day, my mental model of how a computer works is the Apple ][.

Indeed. I have often wondered why university courses tend to use their own made-up machines to teach this stuff, as opposed to using the Apple II (or some of its near-contemporaries).

I think some of it is just aligning with more modern computing technologies combined with the people who write the materials have lived rapid evolution of computing technology and decided it was best to use a generic abstraction that better reflects contemporary technology. I’d note that Knuth, in The Art of Computer Programming moved his abstract machine from MIX to MMIX, the latter being a RISC instruction set, the former being more aligned with 60s style machine instructions.

Re: The Apple Disk II Controller Card (2021)

#26

Post by TMWNN »

alnwlsn wrote: post #23
TMWNN wrote: post #3

As zellyn said, Disk II is pure genius writ large. It's flabbergasting how good Woz's designs were. Almost on a whim, he with the Disk II did something no one anywhere in Silicon Valley—anywhere in the world —was doing. Forget about IBM, HP, Shugart, Tandon. Just within Commodore and Tandy, Apple's direct 1977 competitors, there were abundant human and engineering resources to come up with a fast, inexpensive, and re…

I mean, in 1978 Tandy used standard drives and a disk controller IC, and still managed to sell a whole 16K TRS-80 system with disk drive for the same price (TRS-80 Level II 16K + Expansion Interface + disk drive = $1786 [0]) as Apple (Apple II + Disk II + drive = $1790 [1]). Plus, the TRS-80 came with a video monitor wheras Apple did not. But the Disk II could hold more data per disk, and I'm sure Apple's margins wer…

> I mean, in 1978 Tandy used standard drives and a disk controller IC, and still managed to sell a whole 16K TRS-80 system with disk drive for the same price

The Tandy products were utter garbage.

Controller = Unreliable. Expansion Interface required for the controller = So unreliable that a robust third-party alternative market developed, including Steve Ciarcia's version. TRSDOS = So unreliable that Tandy has the dubious distinction of being the 8-bit system with the most third-party operating systems.

Reliability greatly improved from the Model III onward, but by then it was too late: Tandy had a) destroyed its reputation (the "Trash-80" nickname did not come out of nowhere) and b) surrendered its colossal market lead to the tiny startup founded by two California college dropouts.

More at https://news.ycombinator.com/item?id=44352856>

Re: The Apple Disk II Controller Card (2021)

#27

Post by TMWNN »

alnwlsn wrote: post #23
TMWNN wrote: post #3

As zellyn said, Disk II is pure genius writ large. It's flabbergasting how good Woz's designs were. Almost on a whim, he with the Disk II did something no one anywhere in Silicon Valley—anywhere in the world —was doing. Forget about IBM, HP, Shugart, Tandon. Just within Commodore and Tandy, Apple's direct 1977 competitors, there were abundant human and engineering resources to come up with a fast, inexpensive, and re…

I mean, in 1978 Tandy used standard drives and a disk controller IC, and still managed to sell a whole 16K TRS-80 system with disk drive for the same price (TRS-80 Level II 16K + Expansion Interface + disk drive = $1786 [0]) as Apple (Apple II + Disk II + drive = $1790 [1]). Plus, the TRS-80 came with a video monitor wheras Apple did not. But the Disk II could hold more data per disk, and I'm sure Apple's margins wer…

If you don't want to believe me that Apple's drives worked and Tandy's didn't, consider why VisiCalc launched on the Apple II in 1979 despite Bricklin and Frankston intending to do so on the Model I,[1] because of the latter's far greater market share.

[1] Not only that, Dan Fylstra (founder of VisiCalc publisher Personal Software) was among the first people in the world to own the Commodore PET and the Model I, having reviewed both for BYTE

Re: The Apple Disk II Controller Card (2021)

#28

Post by brontitall »

ralferoo wrote: post #24

Lots of people are commenting on how unique it was to have a software based disk interface instead of stand alone hardware. And in a sense that is true, but also not. Around that time there were various iterations of floppy controllers, each having a small microprocessor at their core. Just before the Apple Disk II, NEC released the uPD765 which is contains everything needed in one chip, but actually it's mostly just…

I think the point here is that the Disk II controller did _not_ have a microprocessor or microcontroller. Rather, it was driven by software that ran on the system CPU, requiring minimal additional hardware
Post reply on HN