You know you've gotten old when...

[skurk]

My first computer was a ZX81 which ran at about 3MHz, if memory serves...

Correct, but only ~25% of that computing power was used to actually process user programs, the remaining ~75% was used to generate the video output.  A "turbo mode" where the video was disabled was also available, IIRC.

So... yeah.  I'm also old.

[skurk]

And you know you're getting old when...

... you try to explain to a young colleague how math works on a 6502:
 "You've got one all-purpose register, two index registers, an ADD and a SUB command - all 8 bit and integer only, of course."
 "And you could actually do calculations with THAT? Where's the FPU???" :lol:

Try to explain kids today how we did 3D graphics on the Amiga.

We had to do it manually, without any libraries.  3D objects were often written directly into the code, due to the lack of a decent editor.  Each point in the said 3D object had to be multiplied several times in realtime for the 3D-to-2D conversion, shaders and texture mappers were coded from scratch.  All this were done in assembly language, and oh, you had to double buffer everything and watch the CPU usage so you'd have everything run at 50FPS, and... and...