Thought as I have been tidying up lately and came across some oldskool tech of mine that I would do a little write up on this I seem to recall I started the concept for this around 1995.
The image above was the MK1 1.44 floppy upgrade prototype. Should have allowed the internal 720K drive to be replaced with a 1.44meg drive. Despite best efforts the board failed to work correctly Build date 1997.
After a re-think ( I must have got distracted for a while! Probably with Tesla Coils!) the MK2 was built in 2002.
This board does not require any software in order to function with 720/1.44 drives. The board shown works for internal drives only.
Later in 2002 the MK3 was born. This new board requires a little more "logic" to function with no limitations. Currently involved 2 IC's like MK2 version ( not including the floppy controller ). It supports both internal and external drives, both 720K & 1.44meg. It will also be possible to copy to and from 720K to 1.44meg drives with no problems.
The board is fully automatic and like the MK2 version requires no software for it to function. It is possible to build a board with a little less logic by using software though we wanted a fully automatic design with "No fuss" involved. Once fitted you can forget about it.
I remember years ago when I advertised my board on the Atari Usenet groups that I got flamed down for it. I remember some guys saying that several engineers had tried to make a software-less solution and failed, so I couldn't have possibly have designed such a board. Resulted in the usual arguments and I think it was one of the last times I bothered posting in the groups. In fact things got so bad back then that I eventually sold most of my Atari stuff in bulk lots and left the Atari scene totally.
I spent some years in Tesla Coils instead. I was interested in those at the time anyway. Though like all good groups of people, everyone fell out over various things. I got branded as a trouble causer with a brain dysfunction as I was the only one speaking out that people got hurt and ended up in hospital, but nobody would speak up. I got sick and tired of arguments between people and I could really write a book on all the crap which went on! In the end, the groups split apart and I left the Tesla groups for good. I had been a long term member of some other groups as well and left all those and never went back.
2008 was around the time I left the Atari world, going by the dates on my site anyway. I uploaded the first 4 parts of my site and called it "The LaST Upgrade", Basically it denoted my departure from the Atari community. I just got tired of all the arguments and getting flamed, it just wasn't enjoyable any more. I later went back to working on Atari upgrades, around 2012. I wanted to finish all the things I had started.
Like the MK1 & MK2 design, the floppy controller is removed and fitted into the adapter board. The adapter board is then fitted to the ST motherboard.
A few revisions were done of the board and layout.
The first production PCB's were manufactured somewhere around the same time. A fair few of these are out in the wild and people do find them now and then! Production of the HD4 ended in 2008.
HD5 was born next.
I was a revision of HD5 and includes step rate fixes for 720K drives. Production ended in 2012.
The last revision was HD6 which was last produced in 2016.
HD6 sees the move from dedicated logic chips to a single GAL IC. Years ago, circa 1990, Logic IC's were easily obtainable and in recent years are increasingly difficult to find. Because of this the choice was made to move over to a GAL which makes the whole design a lot smaller and gives greater flexibility of the design. While GAL chips are obsolete in recent years, they still seem obtainable reasonably well currently.
One thing that has been in question for some years is the media change issue. I looked into this with TOS104. I found if I booted from a blank floppy then placed in a floppy with programs on it, and opened up drive A:, the GEM window would show blank contents. Even if the window was closed and reopened several times, the new contents would not show. Pressing ESC with the window open refreshed the window and the contents showed. So this clearly shows a issue with TOS in not recognizing the floppy change. As the design now uses a GAL, It allows more features to be added without having to add more logic chips.
While Beta testing on my STE, I found that I had a patched TOS which sets the step rate to 6ms by default. So it would work with 720K or 1.44 floppies without having to worry about the step rate times. Though a lot of people (including myself) do not like the 720K floppies running at 6ms, it often makes the floppy drive sound really loud as its running slower. This was a annoyance of my V4 modules. V5 saw the "step rate fix" so 720k floppies ran at the proper 3ms speeds. So it seems at some point TOS206 had the same "bug".
However since I have now run into issues with TOS forcing 6ms, I adapted V6 to force 3ms back on 720K floppies. 1.44 floppies are forced to 6ms (which then becomes 3ms at 16mhz speeds). So now V6 series sees correct step rate times regardless if it has been forced in TOS or not.
While the V6 is currently in production, I am not sure how much longer. I probably have a few PCB's left for making up more kits in the future. Though (sadly?) a lot are going for floppy emulators these days. So such modules like this are not very popular in recent times With the rise in floppy drives being harder to find as well its evolution really I guess
Older & forgotten hardware and software.
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