Danke schon, Thorsten! @Toastie I just tested my 9750 using your method and @evank's write up. It worked perfectly. I used the "always-on" connections in the Interface A for my test voltage, even though I had a bench top supply on hand. As a testament to robustness, I accidentally grounded out pin 3 briefly. It complained a bit by turning off the power light and squealing mildly. I quickly recognized my error and move the ground jumper to pin 5, and proceeded to test all the 6 output ports and the 2 input ports. All worked perfectly.
I plan to build a DIY Peripheral card for the Apple IIe, based on the schematics, while I keep my eye out for a cheap authentic Apple card in a cow's track somewhere. I will actually most likely build two (or more) of these for additional i/o.
I will build my own interface/translator from the 9750 into modern electronics. The plan is to control my modern-ish robot arm. However, that robot arm is stepper motor powered, therefore, some some electronic trickery may happen on a little translation circuit. (for rough movements approximating precise motor steps.) Or.... I may build another robot arm using DC motors only, and go with more period correct approach. (i.e. doing what I would have done in the 80s had I known about this interface stuff). Not sure which direction the project will go. Might go in both directions simultaneously. The whole thing is an learning and exploration project for me, and maybe can be used as an educational tool as it progresses.
Danke schon, Thorsten! @Toastie I just tested my 9750 using your method and @evank's write up. It worked perfectly. I used the "always-on" connections in the Interface A for my test voltage, even though I had a bench top supply on hand. As a testament to robustness, I accidentally grounded out pin 3 briefly. It complained a bit by turning off the power light and squealing mildly. I quickly recognized my error and move the ground jumper to pin 5, and proceeded to test all the 6 output ports and the 2 input ports. All worked perfectly. I plan to build a DIY Peripheral card for the Apple IIe, based on the schematics, while I keep my eye out for a cheap authentic Apple card in a cow's track somewhere. I will actually most likely build two (or more) of these for additional i/o. I will build my own interface/translator from the 9750 into modern electronics. The plan is to control my modern-ish robot arm. However, that robot arm is stepper motor powered, therefore, some some electronic trickery may happen on a little translation circuit. (for rough movements approximating precise motor steps.) Or.... I may build another robot arm using DC motors only, and go with more period correct approach. (i.e. doing what I would have done in the 80s had I known about this interface stuff). Not sure which direction the project will go. Might go in both directions simultaneously. The whole thing is an learning and exploration project for me, and maybe can be used as an educational tool as it progresses.