RE: JiffyDOS transfer protocol: Any documentation available?

From: COPLIN, Nicholas. (
Date: 2004-10-21 06:03:10

Hi All,

>It might be possible, as JDos syncs with data at the start of each byte, 
>as I recall, but then the byte comes in 4 half nybble (twobits?) chunks 
>of 13-14uS intervals.

From memory of my discussions with Jochen for 64HDD, 
* sync is for each byte
* only 10-11us per bit pair
* accuracy is 1us (hence the stack up over four bit pairs adds up)

Jochen had even concerns that the comparing the sources for KERNAL and DRIVE there were parts which were too close to be reliable... but it works... The other thing to keep in mind is the timing variation due to PAL / NTSC. The drives were all identical clock speeds (eg exactly 1MHz or 2MHz) so best to work from the drive code if cycle counting.

- Nick

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