PDP-8 had auto-increment locations down in low memory in similar style. I suppose the device addressing through memory on lots of machines counts as magic too,
L. Sent from my iPad On 22 May 2011, at 06:39, "Thomas Green" <[email protected]> wrote: > > Kevlin Henney wrote: >> To really demonstrate autoboxing you need to allow the compiler to >> convert from int to Integer: >> Integer x = 1000; >> Integer y = 1000; >> However, if you are after interesting counterintuitive corner cases, >> change the constant to 100: >> Integer x = 100; >> Integer y = 100; >> A direct equality comparison will now compare true because, by >> default, the JVM caches the Integer objects for values from -128 to >> +127 (the range can be extended as an optimisation). >> In other words, your corner case has a corner case. Magic. > > > Back in the sixties, the autocode for the Atlas machine at Harwell had > a fine piece of magic. As an outsider, I could book for an occasional > week there, and while I was there I could run programs twice a day > iirc. I once spent two of those 7 days trying to find out why my > program wouldn't work, panicking desperately about meeting my target, > before discovering that of its 128 registers (called B-lines), the one > I had chosen to use was fitted with a hardware conversion to return > log-2 of any quantity stored in it. > > All the higher-numbered B-lines silently did special things, > apparently. Great if you knew about them. Tough otherwise. > > (For those of you who came late to the party and missed the early > days, an 'autocode' was a slightly-Englished version of machine code. > Bit like a penny-farthing - if you stayed on, people admired you, but > when you fell off it really showed.) > > Thomas > > > -- > The Open University is incorporated by Royal Charter (RC 000391), an exempt > charity in England & Wales and a charity registered in Scotland (SC 038302). >
