AT&T 7300/3B1 High Capacity Disk Upgrade

[lad]

I have been answering a lot of mail about how I was able to get a 190 MB
hard drive into my 3B1.  Well, I decided to post this to the net so whoever
is interested might benefit.

I'm running a 3B1 with a 190MB Maxtor XT2190 in my otherwise stock AT&T
3B1.  How I was able to do this was thru a friend or two and a Newark, DE
firm called IDT.  

Adding anything larger than a 67MB disk to the 3b1 requires adding logic
not already built into the machine.  Apparantly the head select logic can
handle only 8 heads or less,  large hard drives typically have 12 or more
heads.  Also important is the fact that the disk controller in the 3b1 can
only address 1024 cylinders.  

IDT makes a kit called the '3B1 HCD Kit'.  For $300. you get:
	
				*	a WD2010 Controller 
				*	a preprogrammed PLA (mine was a P16R4)
				*	enough 30AWG wire to complete the mods
				*	a diag disk to format/init the drive
				*	Full instructions with diagrams
				*	Phone support

The kit comes complete and ready to begin work.  First you de-solder a
spare set of IC pads on the MoBoard.  Drop in the PLA and solder in.  Next
you have to tack on 9 jumpers,  this 'wires in' the PLA to the rest of the
circuits.  Then you unplug the WD1010 and plug in the WD2010.  Install the
drive,  cable it up,  fire it up,  format and test it and then you install
your software.  That's it.  I bought my drive from a mail order house for
about $1700.  So for $2000. I have a greatly enhanced 3B1.  They claim to
have tested this mod with about 45 different drives.  

Mine's been working for several months without a burp.

IDT is at 1 302 731 1583.  They are also making a SCSI Card for the 3B1.


-- 
        Lawrence A. Deleski         |       E.I. Dupont Co.
        uunet!eplrx7!lad            |       Engineering Physics Lab
        Cash-We-Serve 76127,104     |       Wilmington, Delaware 19898
        MABELL:  (302) 695-9353     |       Mail Stop: E357-302