will put up sample files

I’m going to put up a sample file or two, but I wanted to get the smallest complete group of bytes that I can…. ie like one full sector, etc.

So far, I’m just basically streaming bytes, via disk copy software, from the drive into memory on the amiga. I’m “sniffing” this connection via the daisy chain port, and have that connected to my SX controller. I start up my software right before the copy, and so I’m getting the first 100kb that comes out of the drive.

What I don’t know yet is this: Am I getting the correct amount of data that the drive is actually putting out? I’m going to use DMS or something that allows me to copy exactly one track, and then compare how much data I’ve received to what it should be….. This will be the true proof that I’m close.

I also want to fully decode, by hand (if possible), the MFM data — at least the full sector header, anyways. But this damn goofy amiga MFM spec is crazy, and so I might end up using a couple small routines to do it. I don’t fully understand how it works, but I *do* have the necessary documentation, etc

I’ll have stuff up by Saturday…..

About the author

keith

Amateur Electronics Design Engineer and Hacker

4 Comments

  • If you’re good at C, take a look at FLOPPY.C file from Fellow Amiga Emulator package. It implements some floppy emulation, and there are neat subroutines for MFM encoding/decoding.

    (My newly eBayed A1200 is on its way to me!)

  • I like C alot —- this is the first serious language I started programming in….. On the Amiga, actually, about 16 years ago.

    I found floppy.c, and am going to look at it. I’m a little sloppy with my bitwise operators, because I’ve never used them alot. I also don’t know the implications of some of the operations. Like, for instance, as long as you’ve shifted something, OR’ing two words together “combines” the values together into one word, etc.

    Good job on getting an A1200. What did you end up paying? One of these days I keep telling myself that I want to mount an amiga 500 in a PC case so it takes up less desk space. Also, it has an external drive and power supply, and so that would be nice to have everything mounted in one case. Much more compact, etc. If I could do it in a 19″ rackmount chassis, that might be even nicer!

  • I am not an expert in C, but feel free to ask me if something is not clear in those sources, maybe I could be of some help.

    This very A1200 comes from Dublin. I am not Irish so I’ve got it for $96 – with three joysticks and a monitor which I had to leave out because I have already got one Commodore monitor, plus shipping it to Russia would definitely cost me a mint. Oh, and some 70+ floppies as a bonus.

    I personally don’t like the idea of fitting authentic things like A500 or A1200 into PC case, it seems to me they just loose that very air of what they really were.

    Thanks for the data. I will take a closer look at it tomorrow.