Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!watmath!clyde!cbatt!ihnp4!qantel!lll-lcc!styx!twg-ap!amdahl!pyramid!ucat!pesnta!amd!intelca!oliveb!hplabs!tektronix!reed!nscpdc!atelabs!cds From: cds@atelabs.UUCP (David Shanks) Newsgroups: net.micro.pc Subject: Re: XT controller for two hard disks. Message-ID: <163@atelabs.UUCP> Date: Thu, 25-Sep-86 14:00:08 EDT Article-I.D.: atelabs.163 Posted: Thu Sep 25 14:00:08 1986 Date-Received: Tue, 30-Sep-86 06:25:28 EDT References: <332@mit-amt.MIT.EDU> <218@ima.UUCP> Reply-To: cds@atelabs.UUCP (David Shanks) Organization: AT&E Laboratories, Beaverton, OR Lines: 28 Keywords: XT, disk, controller In article <218@ima.UUCP> johnl@ima.UUCP (John R. Levine) writes: >Look again. The standard IBM controller handles two 10 MB disks. In fact, the controller in newer IBM XTs will handle any combination of two drives out of four drive types. Three of these four types are 20 meg drives. I am writing this article on an XT with 2 Seagate ST-225 (20 meg) drives hooked to its IBM controller. To tell if your controller is of this newer type, look for a four position dip switch near the mounting bracket. Older controllers have solder pads and silk screen markings where this switch could be mounted, but no switch. Older controllers will also handle any two out of four drive types (if you add the switch), but the types are different. I suspect (but do not know) that the only difference between the older and newer XT controller is the switch, and a different ROM (the ROM contains the fixed disk bios including the disk type table). This information is taken from the "IBM Technical Reference, Options and Adapters." The relevent sections are "IBM Fixed Disk Adapter (#6361503)" (for the older XT controller), and "IBM PC 20MB Fixed Disk Drive Adapter (#6139790)" (for the newer controller). Write me if you need to know what drive types are supported, or what the switch settings are for a particular drive type. -- Dave Shanks ..!tektronix!tessi!atelabs!cds AT&E Laboratories 1400 NW Compton Suite 300 Beaverton, OR 97006 (503) 690-2000