From: "Ben A L Jemmett" To: Subject: Re: Questions About DRIVPARM and TaskMgr Date: Thu, 11 Dec 1997 16:57:28 -0000 Message-ID: <01bd0655$dd402fc0$937106c2@highscreen> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit Precedence: bulk >On 97/12/10 Ben Jemmett replied: > >>>I recently installed a 3 1/2 disk drive on it. 720K disks work fine, but I get >>>a "sector not found" error or "general error" when trying to use 1.44 MB >>>disks. >>Old, old, old 8088 - XT or previous, I assume. XTs and previous models >>can't handle drives above 720K - the data seperator on the FDD controller >>can't handle the data rates from 1.44 and 1.2 Mb drives - [...] >This is correct, if speaking of the original XT-FDC controller. But many >XTs today use FDCs on Multi-IO cards which usually support up to >2 drives á 1.44MB (some even support 4 drives á 1,44MB). They also >have a ROM/EPROM which replaces the ROM-BIOS floppy code, so >that these XTs are fully capable of 1,4MB drives. I know- both my Amstrad PC's run these cards for drive B: - I didn't replace A as my original 360K disks need the same drive to work properly, as they do something nasty to the hardware (I think - all I know is it crashes on boot-sector load if you have anything >360K on drive A:). However, it may take a bit of fiddling to disable any on-board controller - on some motherboards it's impossible. My Amstrads have their FDD controller on a large, integrated chip of Amstrad's own design. I had to tell the machine it had one drive (A:), then add the second controller for the second drive. > >>Don't know about the switch, but the drive is not handled by the BIOS, so a >>BIOS patch won't make your system compatible with high density drives. >Not alone. To support 1,4MB drives (on any machine), it needs >- a correctly jumpered 1,4MB drive > (I assume this as given) >- a FDC capable of the high density data rates > (in my former reply I also assumed this as a given requirement) Yes, I was just making sur everyone knew the cards had to be capable of high data rates. >- a software driver, which usually resides inside of the ROM-BIOS, > or in the case of AddOn FDCs, inside of an external ROM/EPROM. > I refer to these ROM-based drivers in Digitial Research s terminology > as ROS (ROM Operating System). I though DR used ROS for the Resident Operating System. Sam thing, I suppose, so no problems... > (A software only driver like 2M s 2M-XBIOS is also possible without > the need of a special ROM. It is just loaded by IBMBIO.COM) You could also have a software-only driver loaded by the MBR or boot sector - like Ontrack's Disk Manager for large HDDs. > >The (Real Mode) DOS kernel consists of two parts, the DOS portion of >the "BIOS" (inside of IBMBIO.COM, that s why I usually call the ROM-based >BIOS "ROS", not BIOS) and the "BDOS" (inside of IBMDOS.COM). In short >words, the high level (and portable) DOS functions (in BDOS) are based on >more-hardware-dependent drivers in the BIOS, which themselfs refer to the >very-hardware-dependent ROS (which can be overlayed by an installable >driver). Well, the terminology differs between authors, some call ROS+BIOS >the BIOS... (which is also true). > >Anyway, given the proper hardware, it is possible to support 1,4MB floppies >in PCs and XTs by a ROS update, or a software driver. Of course, the >later solution cannot be used to boot from 1,4MB floppies, whereas this >is obviously no problem for a ROS-based driver. Unless the floppies need the original drives for some reason - e.g. my disks (see above). Very rare, I would assume. Regards, Ben Jemmett