Category Archives: Ramblings

Thoughts on interesting, amusing or annoying topics

Old computers

A few details about myself

I have been a programmer since 1967 when I learned Fortran IV and assembler language programming on the IBM 360 – a monstrous mainframe computer.

Since then, I have used many different computers and systems, including the PDP3 and PDP11 for which Unix was originally developed, various other forms of Unix, the BBC micro, the PC with all its different operating systems, and now these fun microcontrollers.

Assembler Language is ‘high-level’ machine code programming – you program the registers, memory and all the subroutine calling sequences by hand,¬†using instruction mnemonics and hexadecimal code.

At that time, the operating system offered little protection against runaway code, and a small error could erase the entire contents of the computer, which was a big deal since it was a time-sharing system with dozens of different simultaneous¬†users and you could crash everyone’s program at the same time. To make matters worse, because the whole system had crashed, it was extremely difficult to find out who caused it or why it had happened.¬† This gave me a completely different approach to programming.