Posted By
MMS
on 2020-04-28
18:16:07
 |  Re: Overclocking PAL 264s
I understand the calculation.
Still the fact is that half of the bits transferred between 1551 and the 264 are handshake bits.
So with a less complex protocol (without changing any hardware) 20-30% increase could be easily reached.
As I read in an article, even the current slow protocol does not count with memory and TED status (it could explain the speed, but no).
Apple II's floppy disc drive DISC II also uses GCR coding, and still much faster with a 20 pin cable (15KB/sec), certainly it has it's own controller card (but 1551 had too).
"Both the Atari 8-bit and Commodore 64's disk drives' throughputs were much slower than the Disk II's 15 KB/s, seriously affecting their ability to compete in the business market.".
Because with Commodore drives during saving and loading you just wait wait, wait, and it is not not efficient from the point of business, this time is lost.
This Apple DISC II and it's controller was available since 1979, so there was an existing example of a fast GCR device on the market.
I know 1551 was based on existing mechanism and rotation speed, and C= wanted to reach full backwards compatibility with 1541. (not happened)
On the other hand as the 1541 was fully compatible with the 264 series, so C= could keep it for hobby machines, and could create a more serious "killer" business drive for home office (as 264 marketed by Commodore), like an 1MB SFD-1001 drive with cheaper cable and simple IEEE interface in the dongle, with proper speed. TCBM is definitely a downgraded IEEE-488 interface.
Nope, they made a second small "hobby" floppy drive at a rather high price (controller dongle), and the speed is not as fast as it could be. and the housing is too brittle :-O
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