Subject: REVIEW: ColorBurst
From: Donald Richard Tillery Jr <[email-masked]>
Newsgroups: comp.sys.amiga.reviews

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.
[Mr. Tillery also informed me that there exists a much extended
spray paint tool which goes far beyond Deluxe Paint's 'spotty'
airbrush. -JLT3]
     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
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-masked])