5-1/4 diskette drive on current computers

Chuck Guzis cclist at sydex.com
Tue Oct 23 11:59:13 CDT 2007

On 23 Oct 2007 at 11:00, Christian Corti wrote:

> Yes, the signals are absent. But if you have a look at the datasheet for 
> the super I/O chip (e.g. ITE IT8712) you'll see that the chip still can 
> handle two drives. Just route the signals from the chip to the socket 
> (e.g. with fine wire-wrap wire) and eventually program the chip to enable 
> these signals (many pins have shared functions, the actual function is 
> selected by programming the appropriate I/O configuration register).
> As a side note: many older boards that support two drives can handle four 
> drives with the same procedure. They have /DS0, /DS1, /DS2 and /DS3 as 
> well as the four /MOTORx lines. You only need a second socket and you 
> should be able to use the two additional drives with the proper DRIVER.SYS 
> statement. 

If you're using DOS it might be that simple (if modifying a modern 
motherboard can be called "simple"), but the BIOS configuration 
software for many of these machine allows for only one drive, which 
lets out support on OS-es such as Win2K and WinXP.

Given the poor state of expandability of many modern mobos, I don't 
consider modification a worthwhile enterprise except as an 
interesting exercise.

Anent the configuration situation and a related thread, there are 
chipsets that also allow interfacing a floppy via the parallel port 
with suitable configuration.  But again, your BIOS is going to be a 
problem for this if you're using a "modern" Windoze OS.

Given that the floppy controller is about the only thing in a modern 
machine that requires a PCI-to-ISA bridge, I expect that it's not far 
from vanishing permanently from all new PCs.


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