towmater Posted April 9, 2020 Share Posted April 9, 2020 (edited) I was going to add the jumper to make the external STF Rev C. floppy to boot as drive zero, but that circuit board trace seems nowhere to be found. Does anyone have experience or can suggest an alternative? Edited April 9, 2020 by towmater Quote Link to comment Share on other sites More sharing options...
ParanoidLittleMan Posted April 10, 2020 Share Posted April 10, 2020 To work it properly you need to swap lines Drive 0 and Drive 1 (select lines). They start at PSG chip: pin 19 is drive 1 and 20 is drive 0 . So, single jumper will be not enough. If can not find circuit layout for your concrete board revision need to trace lines with ohmmeter, using schematic - what can find online for sure. And easiest, for some tastes maybe not so good solution would be to cut those 2 pins of PSG chip near to board and put there something with what can swap those 2 lines - what can be 2x alternate switch for instance, what can mount in ST case, so will be accessible from outside. Quote Link to comment Share on other sites More sharing options...
Umberto Posted April 10, 2020 Share Posted April 10, 2020 (edited) As stated above on a STF its the Yamaha 2149 (U19) pins 19 and 20 https://rdemming.home.xs4all.nl/Atari/DriveSwapAtariST/ Edited April 10, 2020 by Umberto Quote Link to comment Share on other sites More sharing options...
towmater Posted April 10, 2020 Author Share Posted April 10, 2020 3 hours ago, Umberto said: As stated above on a STF its the Yamaha 2149 (U19) pins 19 and 20 So where it says "drive select A on the motherboard" it's just wherever pin 20 was going before I bend it up and out of the socket? Quote Link to comment Share on other sites More sharing options...
Umberto Posted April 11, 2020 Share Posted April 11, 2020 (edited) 7 hours ago, towmater said: So where it says "drive select A on the motherboard" it's just wherever pin 20 was going before I bend it up and out of the socket? Yes Edited April 11, 2020 by Umberto Quote Link to comment Share on other sites More sharing options...
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