On 10/15/2012 04:14 PM, Fred Cisin wrote:
>> Of
course. Anything done with chips can also be done with
>> discrete components.
> a "pentium" laptop ?
On Mon, 15 Oct 2012, Rick Bensene wrote:
A Pentium 166 MMX chip, which was a common chip
with mobility features
used in some early Pentium-based laptops uses roughly 4.5M transistors.
Is it
supported by current software?
I have a P166/mmx running current linux ( maxed on ram at 512mb)
no problem. Even a 486 runs linux still and XP!.
A 386 would easily fill several racks if discrete and t would clock at
maybe 5mhz.
Such a CPU,
using small-outline surface mount leadless transistors on
12x9 circuit boards with relatively tight design rules and multi-layer
boards, would take something like 32 boards just for the transistors.
Add in the overhead of other discrete components and you are looking at
something like 81 boards (assuming roughly 2.5 discrete components per
transistor). Not allowing any room for chassis, backplane, board
spacing (for cooling), cooling, and interconnect, the CPU alone would a
cube roughly 21 inches on a side. Add in overhead for the stuff listed,
you'd probably be looking at a cube 2 feet on each side. The CPU by
itself could probably be packed into some kind of backpack, but it'd be
heavy.
That's just for the CPU.
Then you'd need RAM, ROM, IDE storage interface, keyboard interface,
mouse interface, serial, parallel, floppy disk, a video subsystem, and
LCD panel. Just the electronics for all of these things, assuming the
use of ICs of the time rather than trying to make them all using
discrete components, and it's my guess that the result would be too
large and too heavy to carry...not even considering what it'd take to
power the beast.
If you tried to do everything with discrete components(except the hard
disk and LCD display) -- well...it'd be more like something (a pure
guess) like 12 or so 7-foot 19" datacenter racks full of boards, and the
interconnect would be a real nightmare. Power distribution and cooling
would be "interesting". Hardly laptop, much less "luggable".
Don't forget the interface to the 15 000 floppy drives!
Thank you for doing the math!
If you did it the PDP-8 would look small same for the early PDP-8s.
Can we talk about the power supply... nah that would be silly.
Allison
--
Grumpy Ol' Fred cisin at
xenosoft.com