Talk:Epyx Fast Load
How did they do it?
Does anyone know how the FastLoad systems worked? What, technically, did they do?
- Fast loaders used a faster (custom) serial protocol. This was possible because you could send code to the disk drive and thereby modify its operation. Mirror Vax 05:16, 27 July 2005 (UTC)
Thank you! The Commodore_1541 page seems to bear this out:
The 1541 used a bit-serial version of the IEEE-488 (GPIB) parallel protocol. The simple protocol that the built-in DOS used supported only about 300 bytes/s. Some third-party speed-ups, however, could transfer about 4 kilobytes per second over the interface, and some "fast loaders" managed up to 10 kbytes/s.
Indeed, the serial bus timing diagrams on p 364 of the Commodore 64 Programmers Reference suggest that there is a LOT of handshaking that is done between every 8 bits. The computer has to acknowledge receipt of every byte. I suspect one could chain a number of bytes together into a larger block, and the chips will still be able to maintain timing. This seems like it would only be a marginal speed increase, though -- maybe 50%. I'm still curious what else they might be doing.
The Commodore 1541 user's guide suggests two other books -- one of which I may actually own. If I recover it from storage, I will see if it has an answer.
- You need to understand that the protocol is done completely in software. This is actually the root of the problem - even though the 64 had the hardware for a serial port (in the CIA chips), it was not used because of a desire to be compatible with VIC-20 peripherals. Mirror Vax 01:05, 28 July 2005 (UTC)
- Indeed, the UI- command "speeds up the 1541 when used with the Vic-20 only." according to the 1541 user's guide. mdwyer (should really sign up for WikiPedia...) --184.108.40.206 03:23, 29 July 2005 (UTC)