So I was blown away by Roland Gustafsson's fast disk loader, embedded in various Broderbund games, which could read (and write - all the write code was still there in the game loaders) an entire Disk II track in one revolution, without needing to wait for sector 0 to pass under the head, while increasing the usable track capacity from 4096 bytes to 4608 bytes at the same time. It wasn't until the advent of FDOS, DiversiDOS and other such third-party patches that AppleDOS's performance rose above woeful.īut even those patched versions, and Apple's own later ProDOS, still required at least two disk revolutions to read or write a single track. His lovely disk controller, capable of transferring data at 256kbits/sec, ended up horribly bottlenecked by a handful of astoundingly inefficient buffer-copying and data encoding/decoding routines. To be fair, Woz dropped the ball when designing AppleDOS too. Various third party fast loaders did eventually become available for the 1541, as I recall. I know from personal experience that it's possible to transfer 256-byte packets over a processor-driven bit-banging serial link using a 1MHz 6502 (as used in Apple II and Commodore 64) at over ten thousand bytes per second. However, there is absolutely no reason beyond a lack of creative programming ability for the thing to have ended up running at under 500 bytes per second. Done quite a few of those there were special disks involved with an eccentric alignment track whose signal you'd monitor on an oscilloscope until all the odd peaks were the same height as the even ones. This abuse did occasionally cause things to slip a little, which would end up with a trip to the repair shop for disk head realignment. That horrible noise the drive always made was a direct result of Wozniak realizing he could save a lot of money on the circuits to align the read-write head simply by over-running the head into the physical limit stop and allowing the metal on nylon fittings physically slip.ĭon't know that any mechanical slip was involved, just the fact that the head stepper motor can't generate enough force to push a drive head all the way through the back of the casing :-) I've often said that if Seymour Cray is the Bach of computer design, Woz is its Jimi Hendrix. I've written here before about the design of the Disk II controller. A lot of Sierra's better games and graphics are fueled by this elegant madness. Using one timer instead of 4 meant more RAM and computer for much less cost.Īnd in the end, that awkward kludginess lead to some amazing hacks and solutions that found their way into games and other hardware, as though the weirdness and porosity of Wozniak's designs infected many, many people with interesting ways to solve problems. In retrospect it's easy to say "this is an awful hack" when you can swallow a 64 GB micro SD card for the price of a meal at greasy diner, but at the beginning of this era 4K of RAM cost as much as the down payment on a house. They intentionally lobotomized the III to not be fully backward compatible, and it was basically entirely marketing designed, not engineer/hobbyist designed.Īnd the reasons why Wozniak designed the II so sparsely is that chips used to be insanely expensive, and they didn't have IBM's resources and supplier chain to help manage costs. Even Wozniak called that thing a complete failure. The Apple II was not responsible for the III.
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