HP-21 works as a fast counter

[Ache]

Thanks Tony!

Honestly, it hadn't occurred to me that the problem was with the ROM, I took a look at the list of the ROM and as you say, it seems that it gets stuck in the first instruction.

Well, you're right... before changing the ACT, I'm going to try changing the capacitor for a 2.2uF tantalum capacitor... to see if I have any luck.

On Friday I try to buy some and I'll try to see if it works.

If that doesn't work, I'll switch to the ACT for the Panamatik refill. I have read something about it and it seems that it is a good option.

As soon as I try it I'll tell you!

Thank you!!!