[Coco] Re: Re: Re: Disk Basic and 512 byte block floppies.

[Theodore Evans (Alex)]

On Jan 21, 2004, at 11:34 AM, KnudsenMJ at aol.com wrote:

> In a message dated 1/20/04 10:06:38 PM Eastern Standard Time,
> alxevans at concentric.net writes:
>
>> All CP/M disk formats use virtual 128 byte sectors, and a few (very
>>  few) use physical 128 byte sectors.
>
> ISTR that in CP/M, the 128th byte of each sector points to the next 
> sector in
> the file, so you get only 127 bytes per sector, and some real 
> opportunities
> to screw up your file system :-)  Also, this would limit a disk to 256 
> sectors
> total, so maybe I'm not remembering quite right.  --Mike K.

Actually CP/M uses a FAT similar to Disk BASIC, though it does lack any 
way to indicate a partial sector.  All files are 128*N bytes in length 
(though the EOF character ^Z does serve to terminate some types of 
files).  This at least part of the reason why Xmodem (aka Modem7 or 
RCPM) has the characteristics that it does.