XTIDE controller now available

[Chuck Guzis]

On 5 Oct 2009 at 17:10, Dave McGuire wrote:


>    New kludges were devised to exceed this ~137GB plateau  
> (obviously), but I don't know how they work offhand because I've 
> never designed with them.

Think "shadow registers"--instead of each 8-bit register in the task 
file representing an 8-bit quantity, each will accept two consecutive 
output or input commands and accept or return 16 bits.  In other 
words, each register has a flip-flop that directs I/O to either 8 bit 
register.  It's not pretty, but it works.
 
>    Anyway, early BIOSs don't know how to deal with this, which is one 
>    
> of the things that makes this XTIDE controller special.

Well, one can also declare a minimal conventional CHS partition from 
which one boots and then install a driver to access the remainder of 
the drive.  Something akin to the way a drive extender works.  When I 
had my AT, I used some 1224 cylinder MFM drives that early BIOSes 
didn't know how to handle.  So I booted from a smaller partition and 
then loaded my own driver.  With an RLL controller, that gave me a 
whopping 250MB or so.

--Chuck