19 Oct
2006
19 Oct
'06
5:14 p.m.
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)
Disc-to-disc imaging?
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 [1]. 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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