3 ms·
What about the fact the timing hole was on the wrong side? Wouldn't that have affected the hole reader since it would never be able to read through the disk OR
by ninju 7y ago
What about the fact the timing hole was on the wrong side? Wouldn't that have affected the hole reader since it would never be able to read through the disk OR was there a reader on the other side
- dhmiller 7y ago> The APPLE DISK is different than most other drives because it ignores the timing hole, using the motor and ‘soft’ timing techniques instead.
- AndrewStephens 7y agoI don't know about every machine from that era but neither the C64 or the AppleII used the timing hole, relying on special signals on each track to identify the start of sectors.
- jhallenworld 7y agoAtari didn't need it either. The 1771 (or 2793 I think) floppy controller chip (a standard chip for IBM formatted floppies) does need the index pulse for the write track command for formatting. But the signal is just connected to a GPIO (I think on the 1050 drive this was fed by a timer). This saves money, eliminating the need for the index pulse LED and photo transistor. Reads never need the index pulse on soft sector floppies. Each sector has a header with the sector number and an "address mark" (a unique data pattern) used to detect the beginning of each sector and track. Hmm, except the index pulse may have been used for a timeout if I remember correctly.
- myrandomcomment 7y agoCorrect. The C64 would just step the motor to the first track -1 and that is the reason for the head banging you got, as well as for the crappy alignment issues.