The Apple II Europlus uses 4116 type RAM ICs.

On my board, there were about 4 different manufacturers and speeds - obviously some have failed in the past and have been replaced. Without a booting machine however, how can I test that the RAM is working OK?

Thankfully, a circuit for testing 4164 I...

The Z80 softcard is somewhat of a curiosity. Released in 1980, it added a Z80 CPU to the Apple II, allowing CP/M (a popular business operating system) to be ran.

With CP/M gave the ability to run programs like WordStar, dBase, programming languages like PASCAL, and interactive adventures, such as...

As part of the repair process for the Apple II Europlus, I have been testing each IC on the motherboard, to ensure it is working correctly. I have been able to test many of the 74 series ICs with my Xgemu 866 Universal Programmer, but there are some ICs that require more complex circuits to test tha...

As part of diagnosing the issues with my Disk II interface card, I thought I would see whether there were any issues with the PROM, as this would definitely cause issues with reading or writing disks.

The card itself is made up of a number of ICs:

  • SN74LS14N - Hex/6 Way Inverter
  • SN74LS132N -...

While cleaning the keyboard here I noticed a strange problem.

After I had cleaned the keyboard, the machine consistently did not boot correctly. Instead, it would boot to the internal self-test routine. This is usually invoked by pressing solid apple-control-reset. However, instead of displaying...

First step (after cleaning the case etc) will be to fix the keyboard.

Many of the keys stay down when pressed, and some appear to not work at all.

Firstly, I removed the keycaps completely, and cleaned the dust and grime away from underneath the keycaps. I could see with the keycaps removed the...