ralphb Posted December 1, 2018 Share Posted December 1, 2018 The PIO interface has two pins that carry +5V. Is there any use for this, in the TI 99 world or beyond? Centronics doesn't specify those pins, so I'm not sure if they're needed for anything today. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted December 1, 2018 Share Posted December 1, 2018 I think a few cables use the +5V to power some chips and or resistor networks in the cable to make the TI outputs compatible with certain brands of printer. Smith Corona and Okidata immediately come to mind as doing this. . . Quote Link to comment Share on other sites More sharing options...
+Vorticon Posted December 2, 2018 Share Posted December 2, 2018 I use them to power up TTL chips on my interface boards Very handy! Quote Link to comment Share on other sites More sharing options...
ralphb Posted December 2, 2018 Author Share Posted December 2, 2018 I see, then I better keep these. Thanks. 1 Quote Link to comment Share on other sites More sharing options...
+TheBF Posted December 4, 2018 Share Posted December 4, 2018 (edited) I see, then I better keep these. Thanks. A very important difference is the impedance of the power sources. Pin 12 with a 10 ohm source, can provide some current for practical uses. If you need 50mA however the voltage will drop to 4.5V Pin 15 with a 1K ohm source is only useful as a voltage source. Draw 0.05 mA (50uA) and the voltage will drop to 4.5V Edited December 4, 2018 by TheBF 1 Quote Link to comment Share on other sites More sharing options...
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