WTB: HP 9133/9134/9135A, HDD, also non-working

[Paul Berger (Canada)]

The ST-506 was a standard interface throughout its life time and is really only an expanded diskette interface using step and direction signal to position the head and binary signal lines to select the head and the drive providing an index pulse to tell the controller where a track starts. The only way the controller can be sure of where it is on the disk is by reading the sector ID that is written when the drive is low level formatted.

The 10MB ST-412 was also used in the 9134B and I would be surprised if there was much difference between the A and B version other than maybe a jumper or two on the controller card. (134 is just a 9135 without the diskette drive.