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Amiga Floppy

inital results on error correction

While I have yet to actually implement the full-scale error correction as I want to, I did some manual tests today. I basically took a track that I was erroring out on, and swapped in 1-bit away values for the bad bytes.  In some cases, it appeared...

keith
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Latest articles

Amiga Floppy

new isr thoughts

While this new ISR is indeed easier to understand and much more simple, I can’t help but remember what else my ISR used to do for me. The four things I really lose are: 1> Any type of double 1’s protection...

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Amiga Floppy

Latest attempt

Tim mentioned something in the last post regarding SYNC which really had me thinking about how to SYNC the data coming in the drive with the data going to the UART of the USB2SER converter. Then I was thinking, now that...

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Amiga Floppy

Found another UART timing issue

Ok. A post or two back, I mentioned that I wanted to rework the receive UART because it wasn’t working perfect. I fixed that, and now it’s reliably receiving. I also mentioned that my sending uart code was...

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Amiga Floppy

current read problems

It seems as though when I have a read problem, its normally minor, and is a single bit error. I notice that the errors have a tendency for 0s to be incorrectly interpreted as 1s. So I get AB instead of 2B, AB instead of...

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Amiga Floppy

basic schematic

I put up a rough schematic of my design.  It’s not perfect, and will be updated in the near future, but if you are interested.
Click the image below for a full size image.

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Amiga Floppy

Parallax USR2SER

So I got my Parallax USR2SER in yesterday. Man is this thing tiny!! About the same width of my finger, and about 1/3 the length! And its mostly surface mount stuff….. It works like a charm. Easy installation, I...

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Amiga Floppy

new design

I took David’s advice, and I rewrote the code last night. Some highlights: 1. ISR is entirely in assembly. Although I haven’t manually counted, it appears to be about 400ns in length. 2. ISR triggers only...

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Amiga Floppy

Commands A and B implemented and working

Ok.  I got two commands A and B implemented and working. Command B from the PC instructs the SX to enable interrupts, and get ready to receive a track into fram.  This command will eventually be expanded to actually...

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Amiga Floppy

new timing image

I think this is timing from like 97 or so, and this is pretty good. I’ve switched to 93 for the time being, because I’ve had the best results with that. This still shows accurate reading of this particular...

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Amiga Floppy

On speed optimization

The theoretical limit, assuming 300rpm drives, is 200ms per track. Or 400ms per cylinder, or 32 seconds per disk. Most attempts read slightly more than one track. I read 16,384 bytes, or 262ms worth. Right now, if I...

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