19 Nov
2007
19 Nov
'07
9:54 a.m.
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