old processor architectures [was Re: The Strange Birth and Long Life of Unix - IEEE Spectrum]

[James Knott]

D. Hugh Redelmeier wrote:
> | Anyone recall using the PDP-8 RIM loader?
>
> Yes.  You had to enter it using the switches.  It was just used to
> read in the BIN loader tape.

I used it to boot from disk.  The Nova had an optional boot loader ROM.  
If that was installed, you just had to enter the device code into the 
switches and hit boot.

> Since memory was core (magnetized doughnuts), it was non-volatile.
> Most of the time the BIN loader stayed intact, even across power
> cycles.

Entire programs stayed intact.  I could power down a computer, turn it 
on again and restart the app from memory.

> The Altair was similar.  In fact, I'm sure it's system design was
> inspired by minis like the PDP-8.  But its ram was volatile.  I'm sure
> glad mine had an add-on board that held EPROM (it could read and
> program 2708s).
>
> The original Altair kit had only 256 bytes of memory.  You had to buy
> expansion kits for more.

My IMSAI came with no memory, so I bought a 16K board, initially loaded 
with 4K.  I also had a multi I/O board from Morrow's Micro Stuff, that 
could load a 256 byte block of data from a cassette tape and then run 
it.  Later on, I got an EPROM board that used 2716s.



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