johnco@mako.UUCP (John M. Cole) (11/29/85)
I have need for more than 10 meg worth of storage, but when my drive is done formatting, it says I have ~10mb free space. Yes, the drive is larger than 10 mb. Is there anything obvious I have missed? Thanks in advance, John Cole
brown@nicmad.UUCP (12/04/85)
In article <970@mako.UUCP> johnco@mako.UUCP (John M. Cole) writes: >I have need for more than 10 meg worth of storage, but when my drive is >done formatting, it says I have ~10mb free space. Yes, the drive is larger >than 10 mb. Is there anything obvious I have missed? Use the FDISK command and check to see if your DOS partition is set up correctly, ie, it should be the whole disk. Also, you will need PC-DOS 3.0, or greater. I believe that DOS 2.1 and below only knew about 10MB disks. PC-DOS 3.0 (really 3.10 now) knows up through 33MB disks. -- ihnp4------\ harvard-\ \ Mr. Video seismo!uwvax!nicmad!brown topaz-/ / decvax------/
bob@nbires.UUCP (Bob Bruck) (12/04/85)
>In article <970@mako.UUCP> johnco@mako.UUCP (John M. Cole) writes: >>I have need for more than 10 meg worth of storage, but when my drive is >>done formatting, it says I have ~10mb free space. Yes, the drive is larger >>than 10 mb. Is there anything obvious I have missed? > In article <452@nicmad.UUCP> brown@nicmad.UUCP (Mr. Video) writes: >Use the FDISK command and check to see if your DOS partition is set up >correctly, ie, it should be the whole disk. Also, you will need PC-DOS 3.0, >or greater. I believe that DOS 2.1 and below only knew about 10MB disks. >PC-DOS 3.0 (really 3.10 now) knows up through 33MB disks. This isn't entirely accurate, although it is close to the truth. In PC-DOS 2.x, unlike PC-DOS 3.x, the information about the format of the fixed disk partitions was determined at boot time based on the size of the disk par- titions (such as the root directory size, number of FATs, etc.). The al- gorithm used was a simple table lookup based on the number of sectors in the partition and was contained in the IBMBIO.COM startup program. This exact same algorithm was duplicated in the FORMAT routine to initiallize the partition. The FORMAT routine does place this information in the BOOT sector, but that information was not used in the startup sequence in DOS 2.x. In DOS 3.x, the startup sequence (IBMBIO.COM) reads the information about the format of the partition from the boot sector rather than determining it from the partition size. This was neccessary because the algoritm used for de- termining the format changed and they wanted DOS 3.x to be able to access disk partitions formatted with DOS 2.x. Note that partitions formatted with DOS 3.x may not be useable with DOS 2.x (the standard 10 Meg partition will work, though). Now, the reason DOS 2.x would not work with partitions larger than about 16 Meg was because of a bug in the FORMAT routine. Because of the mistaken use of a signed comparison instead of an unsigned comparison, FORMAT would only work for partitions <= 32K sectors. This bug was fixed in 3.x so that par- titions can be as large as 64K sectors. Getting back to the original problem posed by Mr. Cole, it sounds like he forgot to set the jumpers on his Fixed Disk Adapter card, so that the FDISK routine still thinks he has a 10 Meg drive. If his drive looks like one of the 4 drives in the table on the Adapter card, all he will have to do is change the jumper on the card. Otherwise, he will have to burn a new ROM for his fixed disk controller card with a table entry for his drive (is this legal???) or use an FDISK routine from a third party vendor that will enable him to describe his drive (are there any of these comercially available???). Bob Bruck (hao | allegra | ucbvax | ...)!nbires!bob NBI Inc. Boulder, Co.
jjm@pecnos.UUCP (Jim Moseman) (12/05/85)
Actually, it is possible to format a 15MB disk under DOS 2.0 or 2.1. The size is determined by the table selected in the BIOS extension ROM. In my case, I was using a Western Digital Controller which defaulted to table 3. For the ROM, I was using this was for a 10MB drive (4 heads). I put in a jumper on position 3 of SW1 to select table 2 which (again, on the ROM I am using) is for a 15MB drive (6 heads). After reformatting, and running FDISK again, the partition had increased from 10 to 15 MB. All this was done under DOS 2.0. Note: you must make sure that the ROM you are using has a table which matches the characteristics of your drive or allows you to build your own table. By the way, I am using the default interleave factor of 3. Does anyone have any experience with other factors? -- Jim Moseman @ CONCURRENT Computer Corporation, Tinton Falls, N.J. ...!vax135!petsd!jjm
brown@nicmad.UUCP (12/06/85)
In article <558@nbires.UUCP> bob@nbires.UUCP (Bob Bruck) writes:
[discussion about DOS hard disk differences]
Even if no one else says anything, I want to say thanks for the info
about the hard disk partitioning, etc. I have printed it and put it with
my DOS 3.1 Tech Ref Manual, for future reference.
--
ihnp4------\
harvard-\ \
Mr. Video seismo!uwvax!nicmad!brown
topaz-/ /
decvax------/ogasawar@noscvax.UUCP (Todd H. Ogasawara) (12/07/85)
Can't say I know the ins and outs of hard disks under DOS 2.x, but by
following the installations instructions for my 30 megabyte hard disk
from PC Source, I now have a bootable hard disk using DOS 2.0 that
has about 31.5 megabytes of usable space in a single partition..todd
Todd Ogasawara, Computer Sciences Corp.
NOSC-Hawaii Laboratories
UUCPmail: {akgua,allegra,decvax,ihnp4,ucbvax}!sdcsvax!noscvax!ogasawar
MILNET: OGASAWAR@NOSC