Well, it was slower due to a hardware problem. Basically, the hardware serial device had a bug which required a bit bang comms channel to the disk drive. Doing that amidst the sometimes aggressive video DMA is what caused all the slowdowns.

Back in the day I owned machines that did it both ways, but not a C64. My Atari computer also had a smart disk drive. Worked over something Atari called SIO, which is an early ancestor of modern USB. Back then, the Atari machine was device independent and that turned out to be great engineering!

Today we have Fuji Net devices that basically put Atari and other computers on the Internet, even to the point of being able to write BASIC programs that do meaningful things online.

The C64 approach was not much different, working via RS-232. But for a bug, it would have performed nicely.

Now, my other machine was an Apple ][, and that disk was all software. And it was fast! And being all software meant people did all sorts of crazy stuff on those disk drives ranging from more capacity to crazy copy protection.

But... That machine could do nothing else during disk access.

The Atari and C64 machines could do stuff and access their disks.

Today, that Fuji Net device works via the SIO on the Atari, with the Internet being the N: device! On the Apple, it works via the SmartPort, which worked with disk drives that contained? Wait for it!!

A CPU :)

Seriously, your point is valid. But, it's not really valid in the sense you intended.

The slowness was due to a hardware bug in the 6522 VIA chip. The shift register (FIFO) would lock up randomly. Since this couldn't be fixed before the floppy drive needed to be shipped, they had the 6502 CPU bit-bang the IEC protocol, which was slower. The hardware design for the 154x floppy drive was fine, and some clever software tricks allow stock hardware to stream data back to the C64 and decode the GCR at the full media rate.

https://www.linusakesson.net/programming/gcr-decoding/index....

Probably not a fair comparison in some ways but this reminds me of that story of Woz making a disk drive controller with far fewer chips by being clever and thoughtful about it all. I’m probably misremembering this.

The 1541 was slow because the c64’s serial bus was slow. Data was clocked over the bus 1 bit at a time. Various fastloaders sped up the data rate by reusing the clock line itself as a data line (2 bits at a time), later HW adapters adder parallel port or even usb to overcome the serial bus bottleneck.

Basically commodore was gonna use an ieee-488 bus for the drive and then decided it was too expensive late in the design and switched to this hacks serial bus that bottlenecked everything.

There’s more to life and computation than cycles and read/write speed. A generation of engineers began their journey doing these “useless things”

The 1541 was set to be a highly capable and performant machine, but an interface/design bug held it back and delivered dismal performance whenever connected to the C64. They tried to fix it but it couldn't be rescued, so speed freaks needed to wait for the 1570 series.