14 Mar
2005
14 Mar
'05
12:51 p.m.
On Mon, 2005-03-14 at 11:55 -0800, Dwight K. Elvey wrote:
What about cost? (irrespective of how the device physically connects to
the host machine)
I forsee four goals to make it useful:
o Cheap
o Simple to build by anyone with a few electronics skills.
o Open 'source' (all schematics etc. available)
o Easy / quick connectivity
Catweasel seems to lose out on 1, 3, and 4 - and 2 isn't relevant in its
case. Can't comment on how nice its software API is as I haven't looked
at it yet, but doubtless a bunch of us on this list could come up with
something that'd cater for all tastes (plus the really low-level
software would all be open source anyway!)
Personally I'm not a fan of a USB version though; I'd rather have
parallel as pretty much any machine has a parallel port - USB limits me
to newer PCs and Macs (plus software interfacing *might* be harder).
Priorities seem to me to be (highest first):
o Reading disks
o Writing back a disk image
o Decoding disk data on host machine
o Modifying disk data on host machine, re-encoding back to floppy
Happily, that's probably order of complexity too, easiest first :) (I am
coming at this from a preservation point of view, rather than being able
to create disk images for use with emulators, say)
cheers
Jules
From:
"woodelf" <bfranchuk at jetnet.ab.ca>
Look what you are doing is building a generic floppy disk controler.
The only high speed device what you use to sync the data/clock pulses
to the system cpu clock. The rest is software. I'd sooner use a CPLD
designed for generic bit sampling but a PIC would also work with
a digital data/clock seperator. Now would getting the people who do
cat-weasel create a USB version be a better goal?
Ben alias woodelf
PS. What about hard-sectored floppy disks, that too may need reading
too?
Hi
I think you are missing what I am saying. The SPI is just
a shift register that takes an external clock. It can be programmed
to automatically DMA transfer into memory. It is the perfect zero
additional logic circuit to use. You don't need to build a
data/clock separator or anything. Just sample the data.
One could even make the output SPI provide write data. These
chips are designed to load their programs from a single
flash or EPROM so the entire hardware requirement is almost
nothing.
I see others on comp.os.cpm talk about using a 50MHz variant
of a Z80. I think most miss the point. These DSP's are 30 MIPS+
not just 50 MHz clocks. They have enormous capabilities in
a relatively small package. It was like they were designed for
this project. You don't need to create a CPLD since the hardware
part is already done for you.