March 26th, 2007

Iris

The joys of debugging

I can think of more fun ways to spend an afternoon than staring at screenfuls of assembler code trying to spot an error, even with handy tools such as DDT. But not many.

I found it at last, though. Instead of HLRZ 15,(P) I'd typed HRLZ 15,(P). Which is of course perfectly acceptable to the assembler, but does exactly what I didn't want.

The program runs correctly now, and lets me consider Moore's Law (or rather the version, which he didn't state, about computation/money) with a deal of satisfaction. My fairly ordinary PC is happily emulating, in software, a hardware architecture that's running (a somewhat later version of) the operating system that I grew up on. About $1,000,000-worth of hardware, back in the late-mid 1970s, to say nothing of the software and the three-phase power supply...

And it's running it about 6-7 times faster than the real thing, according to the rough benchmark that I spent my afternoon debugging and the DECSYSTEM-2065 at PDPplanet, where I have a guest account.

Oner nice thing about getting older is that there's so much more to be nostalgic about :)
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