@node Hardware
@chapter CPU, Custom chips, RAM and other stuff
This chapter contains questions concerning the Amiga-Hardware.

@menu
* 68EC0xx:: What are 68EC020, 68EC030 and 68LC040?
* FPU:: What's a FPU?
* A1200-HD:: Can I use a 3.5" HD in my A1200?
@end menu


@node 68EC0xx
@section What are the 68EC020 and the 68EC030?
@cindex 68EC020
@cindex 68EC030
@cindex 68LC040
@cindex MMU
@cindex Enforcer
@cindex Memory, virtual
@cindex GigaMem
Motorola, the company producing the 680x0 family offers crippled versions
of their processors. They are a little bit cheaper than the originals,
that's why Commodore decided to build the 68EC020 into the A1200 and the
68EC030 into the A4000/030.

The difference between the 68020 and the 68EC020 is that the latter can
address just 16Mb of memory. That's why the A1200 cannot have more that
10 Mb RAM. In most cases you will not notice the difference.

This is not the case for the 68EC030: Many owners will notice that the
68030 has an MMU and the 68EC030 doesn't have. There are some important
programs depending on an MMU, for example Enforcer (a debugging utility),
GigaMem (a program to emulate virtual memory) or all current Unix versions
(@pxref{Unix}). Other Amigas than the A4000 and the A3000 need an additional
processor card to run these.

Finally the 68LC040 is a 68040 without FPU. @xref{FPU}.


@node FPU
@section What's an FPU?
@cindex FPU
The first 680x0 processors (upto 68030) could process integers only.
Floating point operations had to be emulated by the software. An FPU is a
chip (or part of a chip) that can process floating point operations, a
mathematical coprocessor.

One separates three FPU types on the Amiga: The 68881, 68882 and the 68040's
internal FPU. The 68882 is up to 1.5 times faster than the 68881, because it
is splitted in two parts: A conversion unit (the FPU's are using an 80 bit
format internally) and the arithmetic unit. The 68040's internal FPU adds
a pipeline, but misses the trigonometric instructions of the others. These
are still emulated by the software, 68040.library for example.

Special programs (Raytracing, DTP, Mathematics, TeX) are offered in a
special coprocessor version which are up to 50 times faster than the original
versions.

Michael Kaiser (kaiser@@ira.uka.de)


@node A1200-HD
@section Can I use a 3.5" HD in my A1200?
@cindex HD (A1200)
@cindex A1200 (HD)
Many people would prefer to use a 3.5" instead of the smaller 2.5"
drives as the former are much cheaper. This is possible, but you need
a special cable to connect the drive to your IDE controller. Additionally
you should put some isolating material between the drive and the main
board. Some people report termic problems but I did not notice
anything.

Some dealers offer a set which contains the cable, isolating material
and for about 20$. See the magazines for more information.

Thomas Schuh (thomas@@stepout.tynet.sub.org)