Re: [comphist] Lost arts from the 8 bit days.

[Rob L. <la...@tr...>]

On Wednesday 02 October 2002 08:57 pm, Patrick O'Callaghan wrote:
> Rob Landley wrote:
> >One advantage of the 8 bits is there wasn't enough space to get truly
> > lost. No mater how intricate, non-obvious, or obfuscated, it was still
> > 64k of ram, and you could read through the whole thing from start to
> > finish, in hex, in a couple hours.  Maintainability pretty much took care
> > of itself.
>
> If I may pick a nit: 64k corresponds to a 16-bit address space. Whether
> the machine is
> what was usually called 8-bit or 16-bit is neither here nor there in
> this regard. A PDP-11
> (without the MMU) could only address 64kb of memory and early versions
> of Unix
> actually ran on such things. I vividly remember spending rather more
> than a couple of
> hours debugging device drivers, and that wasn't even in hex :-)

True.  The data lines and the address lines aren't coupled.  On the other 
hand, I don't know of any machines that only had 256 bytes of RAM. :)  (Even 
the 4004 could address 4k.  The atari 2600 only had I believe 128 bytes of 
RAM, but it used a 6502 with a 64k address space and a lot more ROM than RAM 
(although not as much as you'd think. :).)

The original PC had 16-64k of ram, depending on how much you ordered.  That 
put it smack up against the 8 bit market, and the CP/M machines (which, with 
their 8080 processor also had 64k address space.  And 8 bit registers).  But 
the chip in it had a much larger address space (albeit in 64k chunks, since 
it was really an 8080 design with bits bolted on...)

Most of the early programs didn't bother with segments, hence things like 
gwbasic which could only handle 64k of ram no matter how much was installed.  
This was actually the big win Lotus 1-2-3 had over the DOS port of visicalc.  
Visicalc was from the 8 bit machines, it could only deal with 64k of ram.  
Lotus 1-2-3 could handle any amount DOS could handle.  (That and the ability 
to scroll the screen display and handle more cells than you could display at 
one time, which is more or less related to having more memory to play with...)

> poc

Rob