Intro and 9133D HDD

[Paul Berger (Canada)]

Those jumpers specify what model of 9133 it is, and the difference between the models D, H, and L is the size of the drive installed, which seems very likely to amount to it change the drive geometry expected. The service guide also lists the specs for the drive used in each model and by comparing that to the specs of the drive you have in hand you can determine if the drive you have is suitable. The only requirement is that the drive you want to use has at least as many heads, tracks and sectors / track as the drive you are replacing. Keep in mind that when you read the specs for a drive the sectors / track will usually be in 512 byte sectors while some HP devices of this era used 256 byte sectors, so it can probably fit twice as many 256 byte sectors as 512 or at worst 2x-1 since there is some overhead for each sector. The ST-506 is not a smart interface and just moves the head comb from cylinder to cylinder based on pulses on the step line and the current state of direction line, and head is selected by the binary count presented on the 4 head select lines. There is no way for the controller to know what drive model is on the end of the cable, unlike a smart interface like SCSI where the controller can interrogate to device to find out what it is.

Paul.