Looking for an 8 bit FDC...

[Allison]

Joe R. wrote:
> At 03:26 PM 10/25/05 -0400, you wrote:
> 
>>>Subject: Re: Looking for an 8 bit FDC...
>>>  From: Jules Richardson <julesrichardsonuk at yahoo.co.uk>
>>>  Date: Tue, 25 Oct 2005 19:14:52 +0100
>>>    To: General Discussion: On-Topic and Off-Topic Posts
> 
> <cctalk at classiccmp.org>
> 
>>>Chuck Guzis wrote:
>>>
>>>>>Intel's 8271 looks like a possibility at the moment, but I thought I'd 
>>>>>poll the list for alternative ideas too. FM support is of course 
>>>>>critical - MFM is less of an issue as the host PC can handle that.
>>>>
>>>>
>>>>The 8271 is a pile of worms.  Don't even bother with it.
>>>
>>>:-)
>>>
>>>
>>>>In a DIP package, if you want to restrict yourself to 5.25/3.5" MFM and FM
>>>>(but not HD) formats, the WD 1770/1772 is a nice compact (28 pin)  little
>>>
>>>I've certainly got 1770 chips lying around unused in the parts box... I 
>>>think you've just put that at the top of the list :)
>>>
>>>
>>>>Why a floppy to support your device, though?  There are many high-speed
>>>>interfaces available to choose from nowadays.  Why not feed your device
> 
> via
> 
>>>>USB?
>>>
>>>Rationale:
>>>
>>>I'm interested in doing this in order to archive old floppies to modern 
>>>media, and out of the 5 or so PCs I can lay my hands on at home, none 
>>>are happy with FM data :-(
>>>
>>>Catweasel's ruled out on grounds of cost, lack of schematics, and the 
>>>fact that it's an internal board anyway.
>>>
>>>I need an external box of tricks so that I can easily use it to do 
>>>archival work both at home and at the museum (and potentially other 
>>>locations too). I know the museum PCs have serial and parallel ports, 
>>>but not all of them will have USB; plus I'm hoping to spend zero cash on 
>>>this and just use parts lying around at home - I'll have various serial 
>>>& parallel I/O chips but certainly no USB stuff!
>>>
>>>
>>>
>>>As an additional thought whilst writing this (admittedly not thought 
>>>through yet!) serial might be nicer than parallel so that at some future 
>>>date I can dump all of the necessary firmware onto the disk interface 
>>>box's ROM and in theory just talk to it using a comms package from the 
>>>PC host.
>>>
>>>Lots more work in terms of understanding the various download protocols 
>>>to do it that way, and it means that the disk interface box needs to 
>>>understand the resultant disk image format on the PC which I'm not sure 
>>>I like... but it does mean that all the host PC needs is a serial port 
>>>and some comms software (which is covered by pretty much any modern-ish 
>>>PC OS on the planet) rather than any special application to drive the box.
>>>
>>>If serial's the standard interface though it'd be zero hardware changes 
>>>to support this in the future - it just means being stuck with a slower 
>>>serial protocol for disk image transfer, when parallel would be faster. 
>>>And yeah, I think we've been over this on this list before... :-)
>>>
>>>cheers
>>>
>>>Jules
>>
>>
>>If you have an older box with ISA bus there is a direct solution..
>>
>>Put a 1793/2793/1770 on a ISA protoboard and run it direct from the
>>PC.  Then all you need to write is software to make it go.  There's
>>absolutly no reason why you cannot do that.
>>
>>Allison
> 
> 
>   I have a used ISA Proto board that I'll contribute to the effort.
> 
>     Joe

It's Jules thats doing this.

Me I have an old XT ISA card that used a raw 765A and 8229 that I modded 
for any rate I want and it even could talk to 4 drives without a twist!


Allison