| Article 46 of comp.sys.amiga.reviews:
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From: drtiller%[email protected] (Donald Richard Tillery Jr)
Newsgroups: comp.sys.amiga.reviews
Subject: REVIEW: ColorBurst
Keywords: hardware, graphics, 24 bit
Message-ID: <[email protected]>
Date: 28 Jul 91 18:12:46 GMT
Sender: [email protected] (Jason L. Tibbitts III)
Reply-To: Donald Richard Tillery Jr <drtiller%[email protected]>
Followup-To: comp.sys.amiga.graphics
Organization: The Amiga Online Review Column - ed. Jason L. Tibbitts III
Lines: 303
Approved: [email protected]
Old-Message-Id: <[email protected]>
Much maligned, and often doubted, M.A.S.T. (Memory And Storage
Technology) has delivered what appears to be a solid leader in the
24 bit display device race. This device will connect to ANY Amiga
model, and display a rock steady, video compatible, 24 bit image in
any of the standard Amiga resolutions.
ColorBurst 24-Bit Display Device for the Amiga Computer
My Story
I've been waiting since last November when I read a M.A.S.T.
advertisement in Amiga World about the ColorBurst 24 bit display
device. Armed with an inordinate amount of blind faith, I have
been in constant contact with M.A.S.T. since then. I was the
first person on their domestic list of interested parties, and
all the patience, understanding, and assistance I could muster is
beginning to pay off.
The completed PAL ColorBursts (the European video standard)
have been shipping for a couple of months now. The NTSC
(American standard) units have one large obstacle to overcome
that the PAL units do not -> the F.C.C. (Federal Communications
Commission). All American electronics devices must be tested to
be sure that they do not interfere with other devices. Like all
dealings with the federal government, this often takes much more
time than seems reasonable. Currently ColorBurst has passed FCC
Class A (this took 6 months), which allows its distribution on a
commercial level and to developers. FCC Class B (which will
allow sales to private individuals) will surely follow, but who
knows how long (complain to the FCC, not MAST).
On Monday July 15, 1991, the UPS man delivered one of three
NTSC units available for developers (more units go into production
at the end of August). After paying the COD, I unpacked the
unit, which includes the ColorBurst itself (approximately 5" x 2"
x 8", with power and active indicators on the front panel), a 16
V AC adapter power supply, video cable, 65 page notebook style
manual (nice for future updates), and two 3.5" disks of software.
I carefully hooked up the device to my Amiga 2000 (with extras)
in accordance to the short but adequate installation instructions
(although they really should be closer to the beginning of the
manual). I then ran the test/alignment programs on the included
disk, and failed. The software seemed to be functioning, but
the unit's active light never lit, and no 24 bit images showed on
my screen. On the way to deliver the unit to UPS for return to
M.A.S.T., I opted to test the unit on my girlfriend's A500. I
was dumbfounded when the unit performed flawlessly! The
ColorBurst unit uses the digital signals present on the video
port to receive the 24 bits of digital data (this is similar to
the way the HAM-E and DCTV devices function). However, in the
ultimate turn of irony, my particular Amiga was missing these
digital signals and did not work with the ColorBurst (I had never
tried the HAM-E or DCTV on my machine, but they don't work with
it either). I was eventually able to swap mother boards with a
friend (for a nominal fee - he doesn't plan on using an external
24 bit device ;-), and I have been able to test the unit since
then.
Hardware
The hardware of the ColorBurst is a high quality piece of
workmanship that includes an internal fan for cooling. The video
cable is a bit of a mess with 4 external wires as well as the
shielded cable. M.A.S.T. assures me that they are working on a
source for better cables, but they didn't want to hold up
shipping ColorBurst while a contract is solidified.
ColorBurst will work with ANY Amiga model from the A1000 to
the A3000. It plugs into the 23 pin video port and you plug your
monitor into it. When not displaying 24 bit images, it passes
through the normal Amiga video.
Those functions that I can attribute to the hardware itself
indicate it is a fine piece of work. When displaying a 24 bit
image as a backdrop for Amiga screens, it effortlessly switches
between non-interlace and interlace as the Amiga screen changes.
Output of the ColorBurst is RGB analog and is comparable to
the standard Amiga video signal (sorry, no de-interlaced version
here). It will display up to 24 bitplanes and has provisions for
a 24 bit image with a 24 bit overlay (the purported 48 bit mode).
The actual image produced by the ColorBurst unit is a very clean
(albeit brighter than standard Amiga video - hand on the
brightness knob) and fantastic picture as viewed on 1084 and 1950
monitors. I have not had the opportunity to dump the image to
video tape as of yet (I don't have that kind of hardware), but I
can safely assume that it would record as well as the Amiga
signal it emulates.
The unit is compatible with my Commodore de-interlacer and
M.A.S.T. says the Microway Flicker-Fixer is compatible as well.
The manual mentions that the NewTek Video Toaster and ColorBurst
have problems and mention a board level modification for the
Toaster to allow compatibility. Some internal genlocks also
evidently have problems (according to the manual), but the remedy
will most likely have to be on a model by model basis.
Software
The software definitely could use some improvement. In its
current version, it all works well, but it has some inherent
flaws.
All programs will load standard IFF files (including IFF 24,
but excluding HAM and Extra Half-Brite) as well as the ColorBurst
fast-load format (a non-compressed format). My system consists
of an A2000 with GVP A3001 at 30Mhz (that's a 68030 & 68882) with
4 Megs of RAM, a HardFrame 2000 and a Quantum 210 hard drive.
The conversion of a 768 x 480 image from the hard drive to
viewing takes about 18 seconds, while the ColorBurst format file
takes less than 4 seconds to show.
Accompanying programs include Show24 - shows images until
left mouse key pressed, Convert24 - converts IFF to ColorBurst
fast-load format while viewing the process, BackDrop24 (This
program was mentioned in the manual, but was not included on the
actual distribution disks I received. It is, however available
from the M.A.S.T. support BBS for the cost of the long distance
call to download it.) - "genlocks" a 24 bit image behind the
standard Amiga screen, Kill24 - turns off any currently displayed
image, SlideShow24 - utilizes a script file to sequentially view
images, Color_Cycle - demonstrates the 24 bit color cycling
ability of the ColorBurst, Sound_Cycle - color cycles in sync
with audio provided through a parallel port audio digitizer,
Scroll24 - allows real-time scrolling of an image using the
mouse, Mouse24 - functionally the same as Scroll24, and CBPaint -
the real-time 24 bit paint program (integer and floating point
versions included).
Chip memory is a limiting factor for all of these programs.
A 512 K chip RAM machine tested was able to display about the
first 380 lines of a 768x480x24 image. My 1 Meg chip RAM machine
had no problem with any display size except within the paint
program (see below).
The source is freely available (with the exception of the
paint program, source code is included with the package), and I
am working on re-writing some of the routines before a promised
shared library is released. Each program opens the ColorBurst
screen before checking the image file's validity or even whether
the user just wants the program's usage. Many of the subroutines
make blanket assumptions about the image, the computer and the
system configuration, and at least the Show24 program hits the
hardware directly while looking for a mouse click. Other
examples: one of the test routines malfunctions with an
interlaced workbench; the Color_Cycle demo assumes that the unit
is a PAL unit; and all of the programs have hardwired assumptions
about the size of the images which correspond to the usual Amiga
resolutions.
CBPaint
The paint program is a plain, but adequate implementation
that utilizes an Amiga screen overlay for menus. Its gadgets are
displayed at the bottom of the screen with generic text labels.
The opening menu allows a choice of standard Amiga resolutions
ranging from 320x200 to 736x480. Unfortunately, as of the newest
version, virtual memory has not been implemented yet. This means
that 2 megabytes of chip memory are required to paint in resolutions
higher than 368x480 or 736x240 (640x400 seems to be too large
also). A 512 K chip RAM machine is limited to 368x240. The
program will actually open up the screen in any requested
resolution, but painting can only be done from the top of the
screen to the area where chip RAM runs out. M.A.S.T. promises
virtual memory (fast RAM used for chip, and hard drive space used
for both) in future releases of all the software.
The paint program will load in images in a variety of
formats including the ColorBurst fast-load format, IFF 24,
Impulse's file format, TIFF, Caligari format, and IFF format
(excluding HAM and EHB).
Tools include airbrush (similar to Deluxe Paint's spotty
version), polygon fill, polygon cut, draw fill, rectangle fill,
draw, dots, lines, cut, paste, curve, circle, ellipse, scale and
flood.
The modes menu allows solid, gradient, transparent, texture,
addition, subtraction, conversion to grey (de-Turnerizing ;-),
blending, smoothing (very nice), and tinting among others.
The color requester allows choice of colors for draw color,
gradient color, transparent color and others with RGB or HSV
sliders. It also allows setting 24 bit dithering to give the
appearance of texture.
Extras include a spare screen, magnification, 90 degree and
any angle rotation, grid setting, and horizontal and vertical
flipping of brushes.
Overall the program is adequate for most touch-up work and
some original creativity, but it could easily be improved.
Feedback on an A500 and my accelerated A2000 is very quick.
Operations are comparable to those of Deluxe Paint in speed.
There are a few quirks left in the program (none fatal), but
the version I have now was an update available three days after I
first received my unit. This would indicate that updates will be
forthcoming at regular intervals.
Technical Info
For anyone interested, the following is as much info as I
have at my disposal about the operation of the ColorBurst 24 bit
device.
Whether you know it or not, the 23 pin video port on the
back of your Amiga has quite a few more signals on it than just
red, green and blue analog outputs. Among other signals, there
are 4 digital pins for use with a digital TTY monitor. Normally,
these pins are 1 bit each of red, green and blue as well as an
intensity bit. The most significant bits of the red, green and
blue data values are present on the appropriate digital pins.
The intensity bit is tied (for a reason I fail to fathom) to the
least significant bit of the blue data. What results is a _very_
rough approximation of the colors of the analog screen as
represented by the 16 colors (red, green, blue, yellow, cyan,
magenta, white, black and intense versions of each) that can be
displayed by a digital monitor.
You probably don't know anyone who uses such a monitor with
the Amiga, but those lines aren't a complete waste. The HAM-E
device, DCTV, and now the ColorBurst make use of this high speed
potential data (which is, of course, what my original mother
board was missing, and why it didn't work). For each pixel
generated during a single frame, there are 4 bits being output
through the video port. This represents about 5.5 Megabytes per
second of data.
I won't go into the operation of the HAM-E and DCTV devices,
but the ColorBurst utilizes this data to fill its own 1.5 Megs of
memory and to receive commands from the Amiga. The data from the
Amiga is sent in chunks the size of high resolution screens (which
is what you'll see without it attached, or if your machine's
digital lines are faulty :-), 4 bitplanes at a time. The ColorBurst
memory is in two "banks" that are responsible for the even and
odd pixels in a scanline. The first 12 bits go to the first
bank, 4 bits into the red, green and blue sections respectively,
and the next 12 bits fill the second bank in a like manner (this
information is easily gleaned from observation of the Convert24
program's operation). This means that a high resolution interlace
24 bit image takes 6 full frames (or 1/5 of a second) to be sent to
the computer. A low resolution non-interlace 24 bit image can be
updated 4 times that often, leading to the 20 fps animation
capability of the ColorBurst. With fewer bitplanes, even faster
animation is possible.
The difficulties in data manipulation and transfer become
apparent when it is realized that the data being dumped out of
the video port must come from chip RAM (hence the limitation on
screen size even in 1 Meg Agnus machines). It will require full
implementation of virtual memory (and more specifically virtual
CHIP memory) before the limitations can be lifted and before
animation can be accomplished (the software doesn't exist yet).
Most hard drives can only deliver 1 Meg per second, so animation
will most likely have to come from memory. This obviously limits
the size of such animations.
I hope to get more specific information in the next few
weeks. Armed with such knowledge, I feel confident that I can
speed up the loader and the converter, and put out a version that
will deal with HAMs, EHB images, and possibly even GIFs.
[Ed. Note: In conversations we've had, Mr. Tillery gave me some
additional words to pass on, mostly on minor points which were left out
of the original review. I include them here. Also note that the wording
is partially mine. -JLT3]
Here are the displayable resolutions of the ColorBurst:
NTSC:
320x200, 384x240, 320x400, 384x480 (Low resolution, interlaced or
non-interlaced, with or without overscan)
1-7, 8, 12, 15, 18, 24, 48 bits per pixel.
Note that the 48 bpp mode is the mode which uses two overlaid 24
bit screens. This is not a 281 trillion color mode!
640x200, 768x240, 640x400, 768x480 (High resolution, interlaced or
non-interlaced, with or without overscan)
1-7, 8, 12, 15, 18, 24 bits per pixel.
It really looks like the software (I looked at and analyzed the code
quite a bit) makes the decision on the mode.
Here are some brief comments on the quality of the provided manual:
I don't particularly like the order of all the info (the installation
section is on page 11 after all the technical info, copyright, some
software excuses and a 24 bit description) But it does have a decent, if
brief, description of the software that comes with it including the test
programs and then the last 55-60% of the manual is for the paint program.
There are a few pictures, but no color ones. About one every fourth page
or so. Actually, the pictures are not even full screenshots; they just
cover the paint program's control panel overlay which is about 40 lines
or so on a non-laced screen.
ColorBurst 24-Bit Display Device
$699 (list according to August Amiga World)
Memory And Storage Technology
1395 Greg Street
Suite 106
Sparks NV, 89431
(702)359-0444
Rick Tillery ([email protected])
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