Looking for an 8 bit FDC...

Allison ajp166 at bellatlantic.net
Tue Oct 25 14:26:15 CDT 2005


>
>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




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