EZ-Drive & Disk Partitions
The ~500MB odd hard disk limitation on my 486 was bothering me, so with the 20GB drive I came across an early 1.x release of Maxtor's MaxBlast. With this it installed the EZ-Drive software into the MBR and allows better use of the drive.
During the process of installing EZ-Drive creating the partitions, it allowed me to create enough 2GB FAT partitions to consume the whole 20GB. Traditionally at best I had only 2 partitions so never experienced this dilemma, and so I had expected it would limit itself to 4 partitions to allow me to use 8GB based on DOS' limitation on primary and extended partitions. Then it occurred to me these would be logical partitions.
At the moment booting up into MS-DOS 6.22 I only see the first 2GB partition which is still a great improvement over the 500MB. However, booting from a Win98 boot disk I see the whole lot. This would instantly make sense to me if partitions had been formatted using FAT32 however they're all FAT.
So what I'm trying to understand is what is it that allows to see all the partitions - is it an updated version of IO.SYS or something? It's the only file I could really think of being loaded into memory that may cause this upon booting. And if it is IO.SYS whether replacing the 6.22 version installed would allow me to see the other partitions natively under 6.22?
During the process of installing EZ-Drive creating the partitions, it allowed me to create enough 2GB FAT partitions to consume the whole 20GB. Traditionally at best I had only 2 partitions so never experienced this dilemma, and so I had expected it would limit itself to 4 partitions to allow me to use 8GB based on DOS' limitation on primary and extended partitions. Then it occurred to me these would be logical partitions.
At the moment booting up into MS-DOS 6.22 I only see the first 2GB partition which is still a great improvement over the 500MB. However, booting from a Win98 boot disk I see the whole lot. This would instantly make sense to me if partitions had been formatted using FAT32 however they're all FAT.
So what I'm trying to understand is what is it that allows to see all the partitions - is it an updated version of IO.SYS or something? It's the only file I could really think of being loaded into memory that may cause this upon booting. And if it is IO.SYS whether replacing the 6.22 version installed would allow me to see the other partitions natively under 6.22?
Comments
You can sort of think of IO.SYS as a set of device drivers for you hardware while MSDOS.SYS is the kernel. In the early days of non-IBM hardware compatibles, the vendor could compile their own IO.SYS, telling it how to access their hardware, and leave MSDOS.SYS unchanged.
Anyway, there are a variety of reasons it may not see the partitions. Win95 re-did a lot of logic in that area.
If I recall correctly, DOS 6.22 doesn't support LBA, so it is in fact limited to 8GB. At startup it needs to parse all logical partitions, so when it can't read the later ones it just assumes they are all bad. If you keep all partitions under the 8GB limit, it should see them.
Yes not normally something I would do, though there had been instances where someone had switched files in NT 3.51 with the NT 4.0 versions for improvements. Can't remember what it was exactly but something disk or memory related I think. Obviously NT is totally different though, though my way of thinking was maybe it's possible.
I believe you are correct with LBA. To be honest, I was expecting the best outcome would be to use 8GB of the 20 in 4x 2GB partitions. However as EZ-Drive is loaded in between the BIOS and DOS and that the so-called DOS 7.x sees them all from the Win98 boot disk that maybe DOS in effect doesn't care that much.
Back in those days I went from a 286 XT to a Pentium 100 in one jump, so I never did experience the 500MB limitation. It's been an interesting learning curve.
Nope: http://www.old-computers.com/museum/computer.asp?c=260
See I've always seen the AT and 286 being mentioned in the same place.