Adding a 3rd floppy to an old PC SCSI controller

[dwight elvey]

> From: cclist at sydex.com
> To: cctalk at classiccmp.org
> Date: Tue, 1 Apr 2008 10:14:38 -0700
> Subject: Re: Adding a 3rd floppy to an old PC SCSI controller
>
> Dwight asked:
>
>> Pardon me for asking but are you sure the chip can provide
>> enough drive? Most floppies expect to terminal with about
>> 150 Ohms. That is more than an unbuffered output of most
>> chips are designed for.
>> Just asking?
>
> Good point--but the datasheet states right in the opening remarks
> that it can be connected directly to the disk drive with its own
> internal 48 ma buffered output and schmitt inputs. The datahseet's
> easy to find on the web--several places have it.
>
> Here, for example:
>
> http://www.tranzistoare.ro/datasheets2/36/366021_1.pdf
>
> I like the DP8473--unlike the Intel 82077AA and later chips, it still
> knows how to do FM correctly--and will even write 128 byte sectored
> MFM, which is something that Intel was ever able to do. Don Maslin
> and I worked through a pile of FDC chips before we found this one.
>
> I think there was a Future Domain card (1680?) that brought all 4
> floppy drives out to 2 headers--and I certainly could have added one
> to do that myself for 4 drives, but 3 on one cable was the easiest.
>
> Cheers,
> Chuck
>

Hi Chuck
 I guess 48ma should be enough. It sounds like a great chip!
Dwight

_________________________________________________________________
Use video conversation to talk face-to-face with Windows Live Messenger.
http://www.windowslive.com/messenger/connect_your_way.html?ocid=TXT_TAGLM_WL_Refresh_messenger_video_042008