THJ@PSUVM.BITNET (William J. Sproule Jr.) (01/21/88)
I need a hard disk controller for a Computer Data Corporation hard disk.
It is an old beast I found on one of our shelfs. I found the specs of
the drive after talking to CDC. It is a 21MB disk, with three (yes, 3)
heads, 697 cylinders, Model# BJ7D5-A. They said it was one of their
Ren-1 (??) models. Any help, especially a controller card that may work
on the beast, is appreciated.
--------------------------------
Bill Sproule MISC/OMA-Penn State Univ.
BITNET: THJ@PSUVM
UUCP: ...psuvax1!psuvm.bitnet!thj
PHONE: (814) 863-4356
las@apr.UUCP (Larry Shurr) (01/26/88)
In article <30329THJ@PSUVM> THJ@PSUVM.BITNET (William J. Sproule Jr.) writes: >I need a hard disk controller for a Computer Data Corporation hard disk. >It is an old beast I found on one of our shelfs. I found the specs of >the drive after talking to CDC. It is a 21MB disk, with three (yes, 3) >heads, 697 cylinders, Model# BJ7D5-A. They said it was one of their >Ren-1 (??) models. Any help, especially a controller card that may work >on the beast, is appreciated. The CDC Wren (note spelling) drives emulate the ST-506 standard and should work with any ordinary controller card. Internally, these drives are different from the Seagate and Seagate type drives in that they have close-loop servo positioning (this accounts for the 3 heads - the fourth head and surface are dedicated to the servo) and a different rotation rate and bit density. This last by the way, means that each track can actually have more than the 'standard' 17 sectors of 512 bytes each. I believe the correct figure is 20 sectors per track. Note that if you configure only 17 sectors per track, your 21 Mbyte drive will yield only 18 Mbytes of usable space. I don't know offhand how to set things up for 20 sectors per track, but as I said, you should be able to use an ordinary IBM PC-compatible controller. In the far distant past I set some of these up in TI Professional computers using the standard TI controller which was actually a third- party ST-506 controller. I could only use them as 18 Mbyte drives, however, because the TI BIOS was hard-coded for 17 sectors per track. regards, Larry -- "The only thing worse than being talked about is not being talked about." - Oscar Wilde, James Whistler or George Bernard Shaw depending on who you ask Name: Larry A. Shurr (cbosgd!osu-cis!apr!las or try {cbosgd,ihnp4}!cbcp1!las) Disclaimer: The above is not necessarily the opinion of APR or any APR client.