From: osmith@acorn.co.uk (Owen Smith)
Newsgroups: comp.sys.acorn
Subject: Re: Amiga / 486 Owner needs information on ARM A5000 / A570(?)
Date: 28 Jul 92 15:11:09 GMT
Organization: Acorn Computers Ltd, Cambridge, England

In article <JKH.92Jul27191234@sparc3.lotus.com> jkh@sparc3.lotus.com
(Jordan K Hubbard) writes:

>1. What's the difference between the A5000 and the A570 (or is that
>   A520?)?  If I want the fastest machine that support SCSI from the
>   outset, which should I buy?  Assume money no significant object.

The A540 is the top end system, with the beefiest power supply, the best
cooling etc. The R260 is the A540 supplied with RISC iX (Unix), 8MB RAM as
standard and an Ethernet card. Given that you seem to want to expand things
to the limits and money is no significant object, I would suggest an A540.
About the only thing you don't get that the A5000 has is the quad density
floppy (1.6MB). The A540 floppy is dual density (800K). Also the A5000 has
RISC OS 3 fitted as standard, the A540 has RISC OS 2. Rumours of an upgrade
are rife :-). The A540 even has the CPU on a removable daughter board.
Look in the FAQ too - some of this information is in there.

>3. What's the maximum practical resolution of the machine?  That is,
>   I'd like a decent array of colors and GOOD refresh rate.  Assume a
>   high-end monitor (well, it's a 17" MAG) that can take whatever the
>   Acorn dishes out.  Can I get SVGA quality graphics, at least? (that
>   is to say 1024x768x256).  Does the Acorn have any graphics assist?
>   If not, how fast can one reasonably expect to be able to push the pixels
>   around?

The official max resolutions of the A540 are 800x600x16x56Hz, 640x480x256x
60Hz and 640x512x256x50Hz. You can push things further sometimes, but the
video memory is on the main bus and so the greater the resolution, refresh
rate and colours the slower the machine although since the ARM3 processor is
cached, the effect is muted. The video system is flexible so you can define
new modes. I'm currently using 960x384x16x78Hz (2:1 aspect ratio pixels) as
I need the high refresh rate to prevent headaches. 800x600x256x56Hz is
vaguely feasible, but the VIDC chip usually can't quite handle it and the
display is speckled. This also steals two thirds of the system memory
bandwidth, and is well out of spec for the machine. I also have a friend who
used a 48 MHz oscillator in a PCATS graphics enhancer (standard is 24,
25.175 and 36 MHz) to get 1024x768x16x50Hz. It worked fine, but his Eizo
9060S monitor couldn't quite display it. 1024x700x16 was OK though. As you
can see, there is some room for maneuver on the video but don't expect
miracles, particularly not in 256 colour modes. There is also a 1152x896x2x
64Hz high resolution monochrome mode on the A540. This is not available on
the A5000.

>4. What are the audio capabilities in comparison to the Amiga?  We could
>   compare with the PC, but even with a Roland GS sound card, it's still
>   apples and oranges.  Given that the Amiga's also digital audio out (4
>   channels), we'll call it the closest comparison.

The sound is 8 bit logarithmic (vaguely equivalent to 12 bit linear) with
up to 8 channels. It is, of course, stereo.

>7. How good is the UNIX port?  What's its lineage?  V.4 or BSD 4.[23]?
>   Anybody using it?

RISC iX (Unix) is not available for the A5000. This indicates even more
strongly to me that the machine for you is an A540 or R260.

>11. Any good magazines for the Acorn user?  Perhaps something that remotely
>   compares with the production standards of PC Professional or Amiga Format?

In my opinion all of the Archimedes magazines leave something to be desired,
compared to the best that can be found elsewhere.

>12. Any other interesting machine features I should know about, given
>    my Amiga / PC background?

The Archimedes isn't really about features, it's about being a nice machine.
The ARM RISC chip set is about the only real feature at the hardware level.
Apple are using a variant (the ARM610) in the Newton. The cooperative
multitasking in the desktop might be called a feature :-).

>Without describing my own current configurations too closely, let's
>just say that both my PC and amiga systems are pretty much the maximum
>available configurations (no 68000's or 286's here) with enough
>additional audio (Roland / Soundblaster / etc) and video hardware
>hooked up that I'm not going to have low expectations for the ARM
>machine.  I.E. I'm not going to be easily impressed, so please
>try hard! :-)

The hardware is going to look OK, but is not going to stand out against your
current systems. You'll need to look at the whole package including RISC OS,
and there I think you'll see some differences. Note that at the moment we
have no floating point hardware, but the A5000 and newer 540s/260s have a
chip socket to take a floating point chip. If you want to try something that
really will knock the socks off everything you've got, get a Computer
Concepts LaserDirect direct drive printer with a Canon LBP-8 engine. 600 DPI
laser printing that goes like greased lightning. My father has one.

Owen.

The views expressed are my own and are not necessarily those of Acorn.