27 Jul
2003
27 Jul
'03
5:51 a.m.
This sounds just about right, vintage-wise!
Ok, so once you have a hole, do you only recover that disk space by
SQUEEZEing the disk?
I think RT-11 works this way, at least I recall the SQUEEZE command
making the disk free space
larger.
Is a FAT needed for this, or is there a simple way to calculate this on
the fly?
Jim Battle wrote:
The wang 2200 that I have (pre 1975) has two modes:
1) direct access. the program and read or write any absolutely
address sector, which is 256 bytes. this isn't what you asked for.
2) random access tape. the first N sectors of the disk contain a
catalog of files on the disk. an entry consists of 8 bytes of
filename, two bytes of starting sector, two bytes of final sector (or
is it size?) and an attribute byte (program/data). it is quite
primitive. if you want to create a data file, you must first reserve
all the space you will ever need for it. unused parts of the file
still take up space. if the file does grow bigger than you had already
preallocated, you must basically shuffle files around on disk to make
room. when you delete a file, it just makes a hole in your map. all
sectors are allocated linearly.
it is very simple, but not too convenient.