DiscFerret: First working hardware, firmware and microcode!

[Philip Pemberton]

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 
index mark")...

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 
desperate.

> Have you succeeded at FM yet?

Got a good read and a datasep lock, but the decoder isn't done yet.

> MMFM?

No samples.

> 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."
 
<http://sliderule.mraiow.com/wiki/Tandy_Radio_Shack_TRS-80_Model_100/Tandy_Portable_Disk_Drive>

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 (!)

Thanks,
-- 
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/