DiscFerret: First working hardware, firmware and microcode!
classiccmp at philpem.me.uk
Wed Nov 3 21:12:17 CDT 2010
On 03/11/10 23:37, Fred Cisin wrote:
> There are 3 inch drives that will hook up to a PC.
The Amstrad EME231 for one. Catch is, mine seems to be fried. If you
enable the write gate and leave WR_DATA high, then read the track,
RD_DATA stays high (as you might expect).
When actually writing to the disc (a 250ns pulse every 4us), I'm getting
garbage back -- random timing gaps between the pulses, from about 2us to
over 200us. The EME153 seems to be pulling the same trick (although
that's even more broken than the 231: the index sensor is stuck at "no
I just swapped the 3in drive for my 3.5in test drive (a Samsung SFD321,
cheap but it works) and an MF2DD disc I found in a desk drawer, and got
a perfect readback.
"Something's rotten in the state of Denmark..."
> 3.25" and some 2.9" ("SA400 compatible") should also work without serious
> problems, although watch out for power connector!
Ya make one mistake and they never let you forget it...!
> 25 years, maybe.
> 20 years would have to include "RLL" and ESDI (RLL has same cabling as
> ST412, but different encoding and data-rates? , ESDI cabling looks the
> same but has signal differences)
Get me the RLL code tables and I'll make that work too :)
> You should already be able to handle most Amiga formats. Think MFM, but
> without the IBM/WD style sector headers and structure.
... but I don't have any AmigaDOS samples to work from. I'd love to buy
an Amiga, but £65 for an Amiga 600, or £85 for a 1200? I'm not that
> Have you succeeded at FM yet?
Got a good read and a datasep lock, but the decoder isn't done yet.
> GCR? (Mac (multiple data transfer rates), Apple 2 (13 and 16 sector),
> Commodore, Victor/Sirius, Apple Lisa, etc.)
See above -- need disc samples to do this. Although a 1541 and an X1541
cable would likely be enough to get the Commodore samples, and 1541s
aren't especially expensive (though from what I've heard they lack a
Track0 sensor, tend to bang the head out of alignment, and in true
Commodore fashion the PSUs tend to burn out in very short order).
> Tandy M100 Portable disk drive disks?
No samples :(
Sounds interesting though. According to the COCI Wiki:
"Uses standard 720K 3.5" floppy disks; format is single side, 40
tracks, 2 sectors per track, 1280 bytes per sector. In short,
incompatible with just about everything."
FM format, 1280 bytes per sector and two sectors per track.... fun.
> Whatever your final system can handle, somebody on this list can find
> another, different format. And, sometimes arguments as to why it is
> important enough to include :-)
If I can figure it out, I'll add it to the format specs. Seems a bit
pointless making an analyser that can only handle one or two formats.
What's amazing at this point is that I've added all these features, and
I'm still only using 8% of the logic capacity of the FPGA, and none of
the on-chip Block RAM (!)
classiccmp at philpem.me.uk
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