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Amiga and Others
~~~~~~~~~~~~~~~~
Part I: The Hardware
by Andrew Wong
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Contents
0. Introduction
1. The CPU and Memory
2. Expandability
3. Expansion Standards
4. Disk Drives
5. Video
6. Audio
7. Keyboard and Mouse
8. Operating Systems' Hardware Requirements
9. In the Next Part
0. Introduction
In a letter published in MD33 Chris Searle expressed interest in a `honest
no-holds-barred comparison of the Amiga Workbench Version 2xx and Windows
3.1 on MSDos machines'. This series of articles attempts such a task. In
it I compare from the user's point-of-view:
· Amiga computers running AmigaDOS 2.0 or greater;
· IBM PC-compatible computers (hereafter referred to as PCs) running
MS-DOS 5.0 or 6.0, Microsoft Windows 3.1, and IBM OS/2 2.0 or 2.1;
and
· Macintosh computers running System 7.0 or 7.1.
The emphasis is on the first two listed. I have had little experience
with the Atari ST and have therefore not included it in this series of
articles. As the ST and Amiga are similar in many respects I hope someone
else will take this up.
In accordance with Chris's suggestion the comparison will primarily be of
the operating systems and user interfaces, but we will begin the series
with a brief overview of the hardware involved.
1. The CPU and Memory
There is not much to be said about the CPU in each system except that the
Amiga and Macintosh use Motorola processors - 68000, 68010, 68020, 68030,
and 68040 - and PCs conventionally use Intel processors. The main CPUs in
the Intel family are the 8086, 80286, 80386, and i486, but Intel, for
commercial reasons, has also released the 386SX and 486SX chips -
downgraded versions of the 80386 and i486 respectively - causing the
corresponding full-specification CPUs to be referred to as the 386DX and
486DX. True to the spirit of cloning that characterises the entire PC
market several other manufacturers such as Cyrix have introduced clones of
the Intel chips, with names like 486SLC, at much lower prices.
Memory, on the other hand, is a big problem for some computers. The
Macintosh has only one type of memory and as such is one of the simplest
machines in this regard. The Amiga has two types of memory - Chip RAM and
Fast RAM, the former being the only type accessible to the custom chips -
and overcoming the division between the two types has not been easy; the
maximum amount of Chip RAM differs with each Amiga model, and Chip RAM is
much slower than Fast RAM; the result is that users who work with sound and
graphics want more Chip RAM and other users want more Fast RAM.
None of the Amiga's problems, however, compare to those of the PC. The
problems originate from the IBM PC's 8088 CPU, which had a 1MB address
space. The IBM engineers assigned 640KB of that 1MB as the computer's RAM
and the other 384KB were to be reserved for the ROM. As the PC became
popular and more memory was needed Lotus, Intel, and Microsoft devised a
way more memory could be added while still working with the CPU's limited
address space; this was called expanded memory. When the 80286 CPU, which
had a 16MB address space, was introduced a new, simpler model for adding
memory was created called extended memory. When the 80386 CPU was
introduced its memory management capabilities allowed it to use extended
memory to simulate expanded memory and to allocate unused regions in the
384KB reserved area as RAM.
None of all this solved the problem that MS-DOS could in general use only
640KB of RAM in which to run programs. This was one of the reasons behind
Windows. Windows applications are not restricted to 640KB of RAM and can
access extended memory freely. OS/2 was created to replace MS-DOS and
Windows entirely; it too has a flat memory model, and OS/2 applications
have only one type of memory to access.
Notwithstanding, memory in the PC, especially for MS-DOS users, is a mass
of jargon and acronyms. The first 640KB of RAM is called conventional or
low memory; the next 384KB is called reserved or high or upper memory; the
first 64KB of extended memory is called the High Memory Area (HMA). The
standard for adding extended memory to the system is called the
Lotus-Intel-Microsoft (LIM) Expanded Memory Specification (EMS); the device
driver that manages its operation is called an expanded memory manager
(EMM). The standard for adding extended memory is the Extended Memory
Specification (XMS). Portions of upper memory used as RAM on a 386-based
system are called Upper Memory Blocks (UMBs). Then there are the DOS
drivers: the XMS driver, also responsible for the HMA, is called HIMEM.SYS;
the EMS emulator and UMB manager is called EMM386.EXE.
2. Expandability
The expandability of the Amiga and Macintosh depend on the model, but most
PCs these days have an ample number of expansion slots available. PCs are
often criticised for having very few facilities on the system board; but
that is a part of the open architecture principle. Most PCs have only the
CPU, ROM, and memory, on the system board and require additional cards for
the video display, any sound capabilities beyond that of the PC speaker,
serial and parallel and joystick ports, and hard disk drive and floppy disk
drive interfaces. Of the 7 or 8 slots usually provided about 4 are used
for these, leaving 3 or 4 free slots. This compares fairly well with the
number of slots available on other computers.
Hardware compatibility can be a problem on the PC, particularly if non-
standard cards such as an unusual display card, scanner card, or network
card are installed. These will often result in a conflict of interrupt
request lines (IRQs) and memory addresses between different cards. In some
cases one can even run out of these resources, such as on an XT-class
computer, which has only eight IRQs available, most of which are already
used by either the system or other devices such as the serial port or hard
drive.
The Amiga has an advantage in this respect because its expansion slots are
governed by a system called Autoconfig, which allows the system to
automatically recognise and configure an expansion card.
3. Expansion Standards
The Amiga and Macintosh are strictly proprietory systems and both have
well-defined standards for adding expansion cards, video cards, disk
drives, and so on. PCs are different in that they have an open market:
manufacture of the hardware is not restricted to one company. It is this,
together with the PCs age, its popularity - leading to the huge numbers of
manufacturers that now exist - and its completely open architecture -
creating markets for just about everything that constitutes a complete PC -
that has lead to a jumble of hardware standards as complicated as anything
else on the PC.
In some cases, established standards do exist, but there are several of
them to choose from. For instance, the standard for expansion cards
depends on the type of system board: PC-XT-class machines have an 8-bit
expansion bus, AT-class machines have a 16-bit bus commonly called Industry
Standard Architecture (ISA), IBM created a 32-bit bus called Micro Channel
Architecture (MCA), other manufacturers rebelled and created the Extended
ISA bus (EISA), and a recent development is the local bus for which no
`official' standard exists but the VESA VL-Bus is the most common.
Some PC standards are not established by a particular organisation, but
exist as de facto standards. For example, video standards were mostly
defined by IBM - CGA, EGA, VGA, XGA, and so on; above VGA the de facto
standard is SVGA or Super VGA, meaning 800x600 resolution with 16 colours,
but above SVGA there are no standards. Other standards are based on
products and manufacturers that are popular and have therefore had
influence in the marketplace: the standard mouse is Microsoft's; the
standard sound card is the SoundBlaster or AdLib.
The Small Computer Systems Interface (SCSI) standard was created to
provide a common standard for peripherals between all systems. In this
way, SCSI hard drives, backup tape drives, scanners, and so on can be
connected to, say, an Amiga or a Macintosh without modification.
Unfortunately, something has gone astray with this principle on PCs and a
SCSI CD-ROM drive, for example, will not necessarily work with any given
SCSI controller card.
4. Disk Drives
The Amiga's floppy drive seems to have improved recently, but for many
years it has been an embarrasment; while other computers had quiet and
efficient floppy drives the Amiga's drive was incomprehensibly slow and
noisy. Being a multitasking computer, the Amiga was also prone to disk
thrashing - a condition in which the floppy drive made a great deal of
grinding noises while getting very little accomplished.
The PC has the problem of having at least four commonly-used floppy disk
formats: 3.5-inch and 5.25-inch disks, both available in double-density and
high-density. It is a problem that stems from the PC's age and makes
working with floppy disks very frustrating.
5. Video
This topic will be covered in the next part of this series in order to be
integrated with a discussion on how the operating system utilises graphics
and what graphics modes it supports.
6. Audio
The Amiga's sound quality has for some time been amongst the best available
and still compares well to that of other machines. Unfortunately, the
Amiga sound chip has not kept ahead of the competition and, while other
machines have improved in this regard, the Amiga has stood still; as far as
concerns sound quality today's Amiga is all but identical to the original
A1000.
The sound in a PC is normally generated through a built-in speaker, and
the quality is abysmal. It was years after the PC's release before a sound
card was developed, which enabled games and other software to make pleasant
sounds, but, until recently, sound cards for some reason still did not
sound as good as an Amiga, despite their ostensibly higher specifications.
However, 16-bit sound cards were introduced on the PC last year, which were
much more impressive than the older cards; and sound cards, particularly
the 8-bit type, are now so inexpensive that all PC users should be able to
afford one.
7. Keyboard and Mouse
One would think that the keyboard and mouse are hardly worth mentioning,
but they are the main input devices and as such can reflect something about
a computer's design. The Macintosh has a one-button mouse, which fits it
well with many people's impression of the Macintosh as a computer that is
easy to use and well-suited to novices, but limited in flexibility for more
advanced users. Having one button makes it impossible to select the wrong
one, but Amiga and Windows users will know that a second button can be very
useful in some applications; the Amiga Workbench and OS/2 also use the
second button to select menus. That the Mac mouse is of high quality while
the Amiga mouse is, well, crap may even say something about the companies
that manufactured them.
Although Apple strenuously asserts that consistency is one of the
Macintosh's best qualities the Mac keyboard is oddly out of line with this
principle: the Mac has had at least four different keyboards and on each
one the cursor keys, Control key, Option key, backtick and backslash keys,
Escape key, and Enter key have been moved all around, and the Delete key
has had two different names.
8. Operating Systems' Hardware Requirements
The hardware requirements of an operating system can give some indication
of its complexity and sophistication. It can also reflect its intended
market: the Amiga's scant requirements, for example, make it suitable for
small systems; by contrast, Microsoft's latest operating system, Windows
NT, will need some 16MB of RAM to run efficiently.
The Amiga's requirements are astonishingly small: 256KB of RAM and a
floppy disk drive, although for efficiency 1MB of RAM and either two floppy
drives or a hard drive are needed.
The Macintosh requires a minimum of 2MB and `a hard drive' for System 7,
though 4MB is better.
MS-DOS requires 512KB of RAM and one floppy drive, but a workable
environment would include at least 1MB RAM and a hard drive. The Amiga is
much more capable in its minimum configuration than MS-DOS is, but MS-DOS
is considerably leaner than Windows, which is why some PC users prefer to
stick with DOS.
Windows requires a 286 processor, 1MB RAM, and 6.5MB of hard disk space,
but a 386SX processor, 4MB RAM, and 10.5MB of hard disk are highly
recommended. Multitasking programs in Windows (which is treated more
thoroughly in the next part of this series) requires more memory to be
effective; I noticed a significant improvement in speed when I upgraded my
PC from 4 to 8MB of RAM.
Supposedly, OS/2 needs a minimum of a 386SX processor, 4MB RAM, and 15MB
of hard disk space, but it is unusably slow in this configuration, and due
to bugs in the version 2.0 installation software it might not install at
all. The recommended minimum is a 386DX processor, 8MB RAM, and 50MB of
hard disk space. With OS/2 more is better.
9. In the Next Part
In Part II of this series we shall examine the operating systems in detail,
including video modes, command-line environments, graphical user
interfaces, file systems, multitasking, and more. A future article will
examine the philosophy and principles of the operating systems and evaluate
each computer's position and future in the marketplace.
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