"intelligent" disk drives

[Christian Corti]

On Sun, 18 Nov 2007, Tony Duell wrote:
> Even later, there was the 9153 (floppy/winchester) and 9154 (winchester
> only) unit. Again 98B09 based, but now everything in SMD packages (the
> 68B09 is a PLCC package). The winchesters are HP custom units with a
> strange interface -- fairly high level for positioning the heads, but
> still the raw bit stream for reading and writing.

Recently the drive in my HP 7958A unit failed (it was a Micropolis 1355) 
and I've replaced the drive with another ESDI drive. The 7958A contains a 
68B09 (I guess) and a NatSemi DP8466 disk data controller.

I had to find a way to lowlevel format the drive so that the firmware of 
the 7958A wouldn't fault after power-on and so I have disassembled the 
firmware. There are three documented options to the Init Media command 
(0=keep all spares, 1=keep only primary spares, 2=keep no spares) which 
all wouldn't correctly lowlevel format the drive. The firmware needs 
additional tracks (called maintenance tracks) at the beginning and at the 
end of the disk. By disassembling I've found out that there is another 
option 3 which will work as option 2 but also format the maintenance 
tracks. So here we go: replace the HDA (in my case I took a CDC WREN IV), 
attach the 7958A to an HP box (HP 9000/840 with HP-IB) and call mediainit 
in guru mode and pass it the initialize option 3. The command terminates 
after a while, and after power-cycling the drive the firmware will pass 
all self-tests now! The self-tests contain read/write tests and ECC tests.

BTW one can use ESDI drives with any capacity as the firmware will read 
the geometry information from the disk drive and setup its internal tables 
accordingly. You have to make sure to jumper the drive to hard sectored 
mode, 64 sectors/track!

Christian