Post B0YdyypheUGn7bybRI by monotonehell@aus.social
(DIR) More posts by monotonehell@aus.social
(DIR) Post #B0YXzCOjKVa3NPCfYG by foone@digipres.club
2025-11-24T02:13:32Z
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so I was playing with the output of my floppy drive, and it turns out with my current setup of greaseweazle + TEAC FD-235HF, I can detect when a floppy is inserted!but only when the disk is marked read-only. writable disks? there's no change in the pins.
(DIR) Post #B0YY1yCyXiNSEl1i6q by foone@digipres.club
2025-11-24T02:14:00Z
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possibly that's configurable. I'll need to see if I can find a datasheet
(DIR) Post #B0YYFtD9v0IsnEkXi4 by foone@digipres.club
2025-11-24T02:16:36Z
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datasheet: http://www.bitsavers.org/pdf/teac/FD-235HF-A529_A540_A591_Specification_Rev_B.pdf
(DIR) Post #B0YYUxSiObiIJxD9d2 by foone@digipres.club
2025-11-24T02:19:17Z
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here we go! You have to try to step the motor for the DISK CHANGE signal to be valid.
(DIR) Post #B0YZZm97zmkAcwuVn6 by foone@digipres.club
2025-11-24T02:31:22Z
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hmm. so I can get it to work by telling it to SEEK to tracks 0/1/0/1/0/1 but that makes noise. I don't want the drive going TICK TICK TICK TICK the whole time
(DIR) Post #B0YZjgym3qsrUvnQXI by foone@digipres.club
2025-11-24T02:33:11Z
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I might need to get lower level than just calling gw.exe.
(DIR) Post #B0YZqy1t4ELmPBimVE by ThePiGuy24@meemu.org
2025-11-24T02:34:28Z
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@foone @foone one of the fun ways about the way floppy drives work is that is somewhat difficult to tell the difference between no disk, and no drive. this makes floppy drives somewhat unintentionally hot-pluggable, provided that the host doesnt try to access the drive whilst it is disconnected ;3
(DIR) Post #B0Yams976FFIxCiFBQ by foone@digipres.club
2025-11-24T02:44:57Z
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ugh. sometime between writing this datasheet and making the silkscreen for the PCB, they removed the labels of the straps, which are pins you can bridge to set different behavior
(DIR) Post #B0YdvuDsKt7HxGoi6C by foone@digipres.club
2025-11-24T03:03:21Z
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so this is the FD235HF-AXXX series of drives, which are based on the FD234HF-7XXX series. there are docs for the straps on the 7XXX, but not on the AXXX. The AXXX is a cost-reduced version of the 7XXX, so apparently they decided that they didn't need jumpers, and also they didn't need docs about which of these ARE the straps
(DIR) Post #B0YdvvAio6BitmLhp2 by foone@digipres.club
2025-11-24T03:07:35Z
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look, there definitely are straps. Those two on the left select disk0/disk1 operation (this is a historical thing caused by shugart vs IBM and I DON'T WANT TO GO INTO IT) but those others are almost certainly straps too, they're just unlabeled ones.
(DIR) Post #B0YdvvxdsDJtLVEm4e by foone@digipres.club
2025-11-24T03:09:10Z
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god I wish I could just desolder this whole board, scan it, and reverse engineer it that way.
(DIR) Post #B0YdvwXRj5xZ8XzMsi by foone@digipres.club
2025-11-24T03:10:38Z
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but okay:the three disk-change straps are: RY34/DC34/DC2RY34 puts out the disk-ready signal on pin 34, DC34 puts the disk-change signal there, and DC2 puts the disk-change on pin 2.
(DIR) Post #B0YdvxCDHWZNAz3vQO by foone@digipres.club
2025-11-24T03:15:04Z
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So if you look at this here, we can see the very interesting fact that one of the pads of S3 is connected directly to pin 2. so S3 (pcb) is DC2 (datasheet)
(DIR) Post #B0Ydvxs2m01vGidKcq by foone@digipres.club
2025-11-24T03:16:15Z
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and the reddish silkscreening between it shows that there's three ways to position this 0-ohm bridge: S3, S4, and S3-to-S4
(DIR) Post #B0YdyypheUGn7bybRI by monotonehell@aus.social
2025-11-24T02:46:50Z
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@foone I think I have bad news for you from the late 1980s... 🫂
(DIR) Post #B0YdyzuLeha0SJ9pJo by foone@digipres.club
2025-11-24T02:57:21Z
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@monotonehell this is doable, silently! it just needs a lower-level interface than the PC could manage
(DIR) Post #B0Ye1ieEHg6RnFuq9o by AMS@infosec.exchange
2025-11-24T03:20:26Z
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@foone That red stuff is glue. This looks like glued and wave soldered SMT.
(DIR) Post #B0Ye1jNxXegO55JMR6 by foone@digipres.club
2025-11-24T03:21:15Z
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@AMS ahh, so the shape makes sense: they had glue in all 3 orientations that 0-ohm resistor could be in
(DIR) Post #B0Ye3Jxp1tbDogqNwO by foone@digipres.club
2025-11-24T03:16:56Z
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this makes sense given the complex way the density select signal is used by the drive.
(DIR) Post #B0YimjUPN9RHpYzlmC by foone@digipres.club
2025-11-24T04:14:28Z
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wow, this 30-year-old floppy drive supports AI! now that's forward compatibility for ya.
(DIR) Post #B0Ymk1QKdWVQOu3Fp2 by agowa338@chaos.social
2025-11-24T04:58:53Z
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@foone Have you considered installing some LLM onto it and trying to sell it to the business people that currently appear to throw money at everything that contains that label?
(DIR) Post #B0YvKn5XhGueHwN4PQ by RueNahcMohr@infosec.exchange
2025-11-24T05:29:40Z
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@foone OMG my drive activity light came on, but the motor didn't start turning.it works as drive 0 but not 1where is the cable twist, did you try the jumpers?😱
(DIR) Post #B0YvKoYeEXmwqUzpPk by foone@digipres.club
2025-11-24T06:35:05Z
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@RueNahcMohr made my own cable, and this model has no jumpers