Thursday, 1 October 2009

QWA Hard Disk Secrets

One thing that has irritated me is that the MKpart_exe supplied with the Q60 is unable to make more than 4 partitions on a hard disk. As each partition can be a maximum of 256MB this makes for colossal wastage of available hard disk space. The final irritation is that the 4th partition has to be set to the remainder of the disk regardless of the size of the remaining space. If there is more than 256MB left this makes for a dangerous partition for smsq/e which due to the 16bit addressing scheme and 65535 file number limit seriously runs the risk of bad things happening on this partition.

There has been little or no information regarding the format of the QWA partition structure up to now. And there is absolutely no information in the public domain regarding the partition table structure apart from what I am about to tell. Firstly lately this site

has publish detailed information regarding the QWA disk structure of the file.
According to the information I have from reading raw files it is accurate.
Secondly a little rummaging around on the first sector of my Q60 hard disk has revealed this : the partition table of the Q60 is on the first 512 byte sector of the hard disk. No real suprise there. It contains an identifier in the first 4 bytes which is $6002. The remainder of the sector is 0 except for 4 partition table entries. The entries start at position $01C6. Each entry is only 12 bytes long. The type of partition is identified by the first 4 bytes which are 1QWA. The next 4 bytes are the start sector of the partition and the last 4 bytes are the length of the partition in sectors and thats it.

The postion of the partition table is not movable within the sector. The first entry has to commence at $01C6. Table entries are editable with a program such as WinEd and so the last partition with its daft size set by MKpart_exe  can be edited to a maximum of 256MB.

Thats all for now but there is more to come on hard disk partitions.

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