Thursday, April 09, 2009


Spectrum+ keyboard & new membrane

Some of the keys were intermittent. For example, the " key took a minute or two before it would work.

I noticed that SYMBOL SHIFT + A did not give me the STOP command while I was writing a simple BASIC program to monitor the Kempston joystick on port 31 which is what jogged my memory (i.e. not getting the STOP command!)

Then, I remembered something about a 22K resistor from the Spectrum+ upgrade manual so downloaded the PDF, saw I was right and the keyboard is now OK after putting a 22k resistor in parallel with R68 on the motherboard.

The resistor calculator was useful to make sure I had the right resistor to hand - it's been a LONG time since university!

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