these RTL or what?

[Chuck Guzis]

On 7 Oct 2007 at 8:49, woodelf wrote:

> Floppy disk is 8 bit I/O. That made all the difference when standard
> floppy disk controlers came out. Ben.

It's not the 8-bittedness of floppy disk I/O that's the problem for 
non-8 bit systems; it's the length of a sector as a power of two 8-
bit characters.  Witness the strange packing used for WPS I, etc. on 
the 12-bit DECstation.

If it were just character size, it would be a non-issue, since we're 
usually talking about characters that are a multiple of 3 or 4.  So 2 
12-bit characters = 3 8 bit characters; 3 16 bit characters = 4 12 
bit characters, etc. 

There was a 2311-lookalike for the CDC systems that had a fixed 
sector size at something like 256 8 bit bytes.  If you're working 
with 60-bit words or 12 bit words, that's not very friendly.  IIRC, a 
great hunk of the capacity went unused, rather than working out some 
sort of packing algorithm to make things come out right.

Cheers,
Chuck