exxos's Atari, Amiga & retro forum

Spun my own PCB for the SidecarT cartridge project.

DoG wrote: 22 Dec 2023 13:57 Spun my own PCB for the SidecarT cartridge project.


SidecarT v0.4 by DoG small.jpg

Nicely done sir.

DoG wrote: 21 Jul 2022 12:54 I also rewired my floppy track display so at the numbers are in the correct location at least.

I just found your project today, first on your YouTube page (after searching the web for a floppy drive track display for the Atari ST), and then here after searching around a bit more to ask about the design.
Your project is very interesting and impressive as I've been wanting to build something like that, and even posted about it yesterday, referring to a similar project I found at AtariAge.

I'm wondering -will the track indicator you've built also work correctly with HD (1.44MB) floppy disk drives (with a HD module circuit of some sort so they can actually be used to read/write to HD floppies)?
is there any chance you'd be posting the PCB files, or even sell boards (bare PCBs or assembled)?

Pacman wrote: 21 Dec 2025 23:58 I'm wondering -will the track indicator you've built also work correctly with HD (1.44MB) floppy disk drives (with a HD module circuit of some sort so they can actually be used to read/write to HD floppies)?
is there any chance you'd be posting the PCB files, or even sell boards (bare PCBs or assembled)?

Thanks. I never finished that project and I don't know in what state I left it at. It doesn't fully work since it never zeros. The only thing these circuits does is counting the steps of the tracks and direction. It doesn't know anything about sectors. It heavily rely on track 00 indicator to function. So it should be fine with HD floppy as well. Since HD is just more sectors and same amount of tracks. As long as it doesn't count over 99.

Some more designs here:
Australian Amiga Gazette #14 has info on a floppy track display.
Elektor Magazine #07/08 (july-aug)1989 also has info on a design.
And ST Format Issue #3 as you mentioned.

DoG wrote: 03 Jan 2026 12:40

Pacman wrote: 21 Dec 2025 23:58 is there any chance you'd be posting the PCB files, or even sell boards (bare PCBs or assembled)?

Thanks. I never finished that project and I don't know in what state I left it at. It doesn't fully work since it never zeros. The only thing these circuits does is counting the steps of the tracks and direction. It doesn't know anything about sectors. It heavily rely on track 00 indicator to function. So it should be fine with HD floppy as well. Since HD is just more sectors and same amount of tracks. As long as it doesn't count over 99.

Sorry to hear about those challenges, though I have a feeling it's one of those "small but essential overlooked details" that could make it work 100% :) According to the videos you appear to be almost there.
In my experience, sometimes a project "going nowhere" just needs is a fresh pair of eyes to look at it from a different perspective and without the history of frustrations and "having tried everything already".
I'm more of an idea-maker/project-researcher myself, missing the EE design-background to finalize many of my own projects, but perhaps someone reading here with the right skills could give a hand by taking a look at it?

What you say about tracks and sectors makes very much sense, so I agree : it'll probably work with 3.5" HD disk drives too. And I don't know of any situation where the drive would go beyond 99 tracks (if I'm not mistaken, some copy protection schemes went beyond the usual 80 tracks by using tracks 81 and 82 as well, but nothing beyond 82 as far as I know).

In my search for more info on the web (on floppy disk track display circuits) I came across the 7-drive track display project at GitHub, again for the Amiga, You might already have seen it, but if not I thought it might shed some new light on your existing project. Unfortunately nothing's come up for non-Amiga systems, so thank you for sharing the link to the Elektor article for PC systems!
By the way; I realized that both articles you posted about were from the late 80s and according to Wikipedia the first 1.44MB (HD) floppy disk drives arrived on the market in 1986, so it's very likely that at least the Elektor article aiming at PC systems would work for those drives as well. I'm not very familiar with Amiga computers, if they included (or could be upgraded to) HD floppy disk drives too, just like our Atari STs could, or if it was DD-only.

Oh, I have a couple of Atari ST specific track display projects that I downloaded from one of the many FTP archives back in the day (several decades ago), but unfortunately I don't know if they're complete/unmodified as I tended to convert image files to more compatible formats etc. and not always keep the original archives, or I'd post them here.
I'll keep searching for the original files, but in the meantime, here are their names in case someone else recognizes them:
- "Track Indicator Mk II" by T. Smith, 1989 (TI_MKII.ZIP or LZH, ZOO, ARC or some other extension ?)
- "Tdisplay" by Beeblebrox industries unlimited, 1991 (TDISPLAY.ZIP or LZH, ZOO, ARC or some other extension ?)

DoG wrote: 03 Jan 2026 12:40 I never finished that project and I don't know in what state I left it at. It doesn't fully work since it never zeros.

I just came across something which caught my attention. Though not directly related, I found this interesting (highlighted by me below in red):

Although most drives reset their Disk Changed signal on receipt of a Step command, some older drives have an explicit Reset signal (eg. on pin 1 of some old Panasonic and Sony drives).

The solution (for Gotek drives) follows in the above link, which might or might not apply to real, physical disk drives, but it might be a step (no pun intended) in the right direction to get it working.

UPDATE: A thread titled Why is the RDY signal on floppy disk drives disabled? discusses much of the same and a forum reply states that unlike PCs, Amiga computers rely on that signal (emphasis by me highlighted in red):

PCs don’t use the ready signal, and since most floppy drives ended up used in PCs, manufacturers could save a little by ignoring it.

You’ll need it if you want to use the drive in some other systems (notably the Amiga, the Amstrad CPC and PCW). It must be active low when a disk is in the drive, and importantly, it must switch to high and back when the disk is replaced.

Some drives have jumpers which can be used to enable the ready signal; others like yours require modifications.

I'm no expert, but I seem to remember (back in the day when I was trying to figure out how to get HD floppy drives to work in my STe) that the ST uses the same type of drives as PCs, only with the need for changing the default "drive select 1" to "drive select 0" jumper so it could be recognized as drive A on the ST and if I remember correctly the 34-pin connector (end of cable from the STe motherboard) needed to be inserted "upside down" (i.e. the wrong way) -if the 34-pin male connector on the disk drive prevented this from happening then the plastic "notch" on the cable's 34-pin female connector had to be cut away first.
So, if you based your track display circuit on the one from Commodore Amiga computers, and Atari ST computers use standard PC disk drives, could it be that your circuit doesn't quite work because it's lacking a signal from (non-Amiga) disk drive? I don't have any of the hardware or schematics in front of me, and this may be a longshot, but could the needed signal for the disk track display be obtained from the drive before the "ready" jumper?

Oh, one of the links in the above forum thread points to What modification is required from a PC floppy for use in Amiga? which could perhaps be helpful. And there's an Open Source floppy disk adapter which allows PC disk drives to be used with Amiga systems.
It further links to the GitHub Floppy Adaptor project which not only supports the Amiga but says that it also the Atari ST/TT. I haven't yet taken a closer look and don't know what this exactly means (for the ST/TT) but again, this might give some leads as what is needed in order for your track display to reset properly.
And here's a page (taken from the above (What modification is required from a PC floppy for use in Amiga?) thread showing the specifics of modifying a number of PC type floppy disk drives from different brands/models to Amiga standards: Jope's drive modification page: Let's modify some drives.
Maybe using this information in reverse could help the (Amiga) track display work with a PC/Atari floppy disk drive).

Another thing I've been thinking about is to add some additional informative LEDs while at it. Personally I would like to have a track display which looks something like this:
The "read" and "write" LEDs can, as you've already stated (alongside your Youtube video I believe) be taken from the decimal points of the existing display board.
As for the others; my Sony MPF-920 High Density disk drive in my STe has 3 micro-switches inside, which detect the floppy disk inserted, so for the "Write protect" LED the WPRT switch can be used (an estimated guess is that other drive brands/models have the same switches, but I can't really say for sure as I only have experience with said Sony drive model).
For showing the density (HD or DD) of the inserted floppy disk, the HDIN (HD detect) switch can be used, and finally there's the CTIN micro-switch which detects if there's a floppy disk inserted at all, or if the drive's empty. I would personally like to have this to turn off and on the LEDs entirely: if no disk is in the drive but the drive spins then none of the LEDs/7-segment display will light up.
Finally, a timeout function could be added so that all the LEDs stop lighting up after a certain amount of inactivity of the drive.

@DoG: have you making any progress on the track display?
Hopefully it's an easy fix concerning the reset signal of different drives.