[  NeXT used 1024 byte sectors by default, but although i'm pretty sure that by
[  NeXTstep 3.3 at least it could use filesystems with other sector sizes.

That does not fit with my experience.  But I'm talking about the low level  
device formatting, at the SCSI transfer level, and not the higher level file  
system.

I believe that NeXT shipped all drives with 512 byte block formatting.  The  
file system used allocation blocks of 1024 bytes, but this meant that pairs of  
512 byte blocks were read at the low level.

I am the author of sdformat, a replacement for NeXT's sdform, which allows a  
drive to be reformatted with 1024 byte blocks at the low level.  It actually  
required manual user intervention to obtain 1024 byte blocks.  The main  
incentive for doing this was so that the low level block access matched the  
higher level file system allocation unit size.

NeXTSTEP for Intel processors did not support this, because the BIOS could not  
boot from anything but 512 byte blocks devices.  Sun SPARCstation machines  
running NEXTSTEP or OPENSTEP also could not boot from 512 byte blocks devices.   
The Sun can handle additional drives besides the boot drive as 1024 byte  
blocks, and I believe Intel could, too.  The strange thing is that all machines  
need to boot from 2048 byte block CD-ROM, so I don't see why there was a  
limitation for other devices to have 512 byte blocks.


Early NeXT computers could not boot from CD-ROM (SCSI) devices, you needed a  
NeXT with a floppy which could bootstrap the CD-ROM.  I believe that this was  
due to a firmware limitation that 2048 byte blocks could not be read, or  
perhaps that the CD-ROM device type was not considered a valid boot device.


[  Apple uses 512 byte sectors by default.

Yeah, pretty much the whole industry deals with drives formatted for 512 byte  
blocks.  Some drives will not even honor the request for reformatting at other  
block sizes.

Brian Willoughby
Sound Consulting