Wow; $192 for a 5.25" floppy disk drive
classiccmp at philpem.me.uk
Thu Oct 19 19:14:56 CDT 2006
Jules Richardson wrote:
> Maybe someone can think of a situation where you *need* more than one
> track in memory at once, though. (Note I'm not thinking at all about
> storage formats which aren't track-based though)
> DRAM, no. In that sort of situation providing a SIMM / DIMM socket would
> seem the best bet and people can populate it with whatever memory they
> have to hand. There is the refresh issue then, though.
Use a CPLD and one of the many free SDRAM-to-SRAM-interface Verilog/VDL models
- <http://www.cmosexod.com/sdram.html> for example.
> Possibly, depending on cost. I'd hope that something could typically be
> lashed together (parts cost only) for about 20 bucks, though using a
> combination of purchased bits and things from the parts bin . Beyond
> that and it's sort of into catweasel territory (albeit with the
> convenience of an external device).
Speaking of the Catweasel, does anyone know what the data it returns actually
means? Is it a 'time from last transition to this one' value, or something else?
(I've read the programming specs, and they're about as clear as mud)
> out how to program a PIC. I would have absolutely no idea what to do
> with an FPGA, let alone be able to contribute anything to the design :)
Verilog isn't particularly hard to learn, especially if you know C.
> From the point of view of the host machine, the set of operations
> needed isn't complex - something like 'assign parameters', 'read track',
> 'write track', 'get error information', 'format track', 'seek', and
> possibly something like 'download firmware'. It shouldn't actually be a
> complex device - but it is best left to someone who has experience of
> building SBC-like devices :-)
That'd be me then.
> Transfer speed is a huge headache - 200KB or whatever at RS232 speeds is
> painful. Repeat for 160 tracks and it becomes rather annoying! (It
> suggests that some sort of simple compression scheme is needed)
Maybe have 115200-baud RS232 and multi-megabit USB as an option?
Add a jumper to the board to switch between them - one position for RS232, the
other for USB.
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