TidBITS#339/05-Aug-96
Geoff Duncan
TidBITS#339/05-Aug-96
=====================
Do you think the Internet is too slow? What if there were a simple
thing we could all do to make it faster? Long-time technology
writer Cary Lu weighs in with a simple suggestion. Also, learn
about hot new Macs from Power Computing, DayStar, UMAX, and
Apple; find guides to everything at this week's Macworld Expo
in Boston; and increase your Mac knowledge as Chad Magendanz
sets down the definitive word on disk images.
This issue of TidBITS sponsored in part by:
* APS Technologies -- 800/443-4199 -- <sa...@apstech.com>
Makers of hard drives, tape drives, and neat SCSI accessories.
For APS price lists, email: <aps-p...@tidbits.com>
* Northwest Nexus -- 800/539-3505 -- <http://www.nwnexus.com/>
Professional Internet Services. <in...@nwnexus.com>
* Power Computing -- 800/375-7693 -- <in...@powercc.com>
PowerTower Pro 225 MHz - the fastest desktop system ever.
Win a PowerCenter 120! <http://www.powercc.com/>
* America Online -- 800/827-6364 -- <http://www.aol.com/>
The world's largest provider of online services.
Give Back to the Net -- <http://www.aol.com/give/>
* EarthLink Network -- 800/395-8425 -- <sa...@earthlink.net>
Providers of direct Internet access for Macintosh users.
For eWorld refugees: no setup fee! <http://www.earthlink.net/>
* DealBITS: Red-hot Macs, RAM, software, and more! <--------- NEW!
<http://www.tidbits.com/dealbits/> -- <deal...@tidbits.com>
Copyright 1990-1996 Adam & Tonya Engst. Details at end of issue.
Information: <in...@tidbits.com> Comments: <edi...@tidbits.com>
---------------------------------------------------------------
Topics:
MailBITS/05-Aug-96
Getting Oriented for the Expo
Text-only Mondays: A Modest Proposal
Getting Through the Media Blitz
<ftp://ftp.tidbits.com/pub/tidbits/issues/1996/TidBITS#339_05-Aug-96.etx>
MailBITS/05-Aug-96
------------------
As you may have noticed last Friday, we sent out the first test
message to almost the entire TidBITS mailing list. It was quite
successful, as was the release of DealBITS that day as well, which
was the first stress-testing of ListSTAR/SMTP. We're not quite
sure whether we'll distribute the first complete issue via
ListSTAR next week or the week after, but it will be soon. In the
meantime, if you are **not** on the TidBITS list and wish to
subscribe (all existing subscriptions will be transferred), send
email to <tidbi...@tidbits.com> rather than working through the
Rice LISTSERV. [ACE]
**Apple Announces New Macs** -- As anticipated in TidBITS-337_,
Apple has announced faster versions of the Power Mac 7600, 8500,
and 9500, along with a new top-of-the-line 9500/180MP that
features two PowerPC 604e processors running at 180 MHz. The new
9500 and 8500 models are based on the PowerPC 604e, whereas the
revamped 7600 sports a 132 MHz PowerPC 604 processor. All the new
machines feature 8x CD-ROM drives and upgradable CPU daughter
cards that should support speeds of up to 250 MHz. Prices range
from about $3,000 for the Power Mac 7600/132 to $5,700 for the
Power Mac 9500/180 MP. Also of interest to owners of recent Power
Macs, Apple announced a 180 MHz PowerPC 604e-based CPU upgrade
card for about $900. Availability of these systems varies; a few
should appear in late August, others should arrive in September.
Additionally, Apple officially announced the Performa 6400-series,
sporting a mini-tower design and PowerPC 603e CPUs running at 180
and 200 MHz, priced from about $2,400 to $3,000. I've heard
reports that some dealers currently have these Performas in stock.
Apple also announced Avid Cinema, a PCI-based digital video
editing system available for $459 as an option for 6400 Performas.
[GD]
<http://product.info.apple.com/pr/press.releases/1996/q4/
960802.pr.rel.pm604e.html>
<http://product.info.apple.com/pr/press.releases/1996/q4/
960802.pr.rel.perf6400.html>
**Clone Wars Heat Up** -- Lest you think Apple is alone in showing
off new machines this week, hold on to your socks: Power
Computing, DayStar, and UMAX are competing for your attention too.
In addition to its recently-introduced PowerTower Pro (see
TidBITS-337_), Power Computing has announced a PowerBase line of
consumer-oriented Mac-compatibles starting at about $1,500. Built
around the PowerPC 603e, PowerBase systems range in speed from 180
to 240 MHz, sport three PCI slots, 8x CD-ROM drives, and (gamers
take note!) video acceleration that improves 3-D texture mapping
and QuickTime performance.
What's more, DayStar is introducing the new Genesis MP 360+ (with
two 180 MHz 604e CPUs, starting at $5,500), in addition to 180 and
200 MHz versions of its four-processor offerings, starting at
$8,500 and $10,000. These systems are targeted at high-end
graphics and video professionals, and DayStar is reportedly
shipping them with _no_ hard disks or RAM to let customers more
easily customize the systems.
Rounding out the pack, UMAX is expected to show a new spate of
SuperMac-branded Mac-compatibles at Macworld, including revved-up
versions of its S900L series and a set of 603e-based "SuperMac C"
consumer machines due in September. The SuperMac C series
reportedly range in speed from 140 to 200 MHz, sport 8x CD-ROM
drives, and range in price from $1,600 to $2,600. As of this
writing, DayStar's and UMAX's Web sites don't cover their new
products, but they'll probably make information available soon.
[GD]
<http://www.powercc.com/Product/CPUs/pbase.html>
<http://www.daystar.com/>
<http://www.supermac.com/>
**BulkRate to Speak TCP/IP** -- Greg Neagle is readying version
2.5 of the shareware BulkRate, an offline message reader for
FirstClass servers. BulkRate lets FirstClass users retrieve mail
and conference messages for reading offline; version 2.5 supports
TCP/IP connections to a FirstClass server, is compatible with
FirstClass's threading features, and can use any available serial
port for modem connections. Though SoftArc, publishers of
FirstClass, have been working on an offline client for years,
Neagle's BulkRate is the only viable solution available now. A
beta version of BulkRate 2.5 is available via FTP or from the
system fc.digitalpopcorn.com (port 3000, username and password
"br", sans quotes) using the FirstClass client. [MHA]
<ftp://users.aol.com/gregneagle/pub/>
Getting Oriented for the Expo
-----------------------------
by Tonya Engst <to...@tidbits.com>
TidBITS-338_ had a MailBIT pointing Macworld Expo attendees to a
Newton-based Boston subway map and noting that Adam will be doing
a book signing at the Macmillan booth on Thursday from 11 to 1.
Last week, I didn't know what booth Macmillan would be in, but
with the help of a Director-based program called booth.finder from
Macworld Online, it appears that the Macmillan will be exhibiting
at the World Trade Center, booth 5604.
Booth.finder enables you to figure out exactly where different
vendors are located and become better oriented to the layout of
the two exhibition halls. You can run the application live over
the Web if you have the appropriate Shockwave plug-in installed,
though I recommend downloading a stand-alone version (available
for Mac or Windows), which you can run anytime you like without
being connected to the Internet. Over my 56K frame relay
connection, it took almost a minute for the plug-in to load.
<http://www.macworld.com/expo/boston.expo.96.html>
Those who are less interested in finding specific booths than in
finding specific parties won't want to miss the Hess Macworld
Memorial Party List. This list was formerly maintained by Robert
Hess, the MacWEEK associate editor who died earlier this year (see
TidBITS-310_). You can view the list on the Web or request it by
sending email to <part...@aol.com>.
<http://www.xensei.com/users/ileneh/HessMemList.html>
If you can't attend the show but have a sufficiently net-savvy
Macintosh, you can take advantage of Apple's reporting about the
show. Apple will be presenting a number of events, including
webcasts of keynote speeches, a spycam, and live chats featuring
Expo "movers and shakers."
<http://live.apple.com/macworld/>
A few other organizations and individuals will no doubt be
providing daily coverage of the show; a quick search in your
favorite search engine on "macworld expo boston" should find those
reports as they go online.
Text-only Mondays: A Modest Proposal
------------------------------------
by Cary Lu <car...@aol.com>
Will the Internet ever get faster? Can the Internet backbone
capacity ever catch up with the increase in demand, let alone get
ahead? Each new Internet development - streaming audio, Internet
telephony, video conferencing - increases the traffic. Even users
with ISDN or T1 connections to the Internet have to wait for many
Web pages, because the fast connection only helps with the final
mile, the connection from your Internet provider to you.
Some Internet services may start caching specific Web sites ahead
of time, so subscribers can get fast access from a local server.
That fast access may cost extra and how the money might be divided
between the Web site owner and the cache owner remains to be seen
(not to mention the copyright issues when copying a Web site).
But, such caching increases the overall traffic because _entire_
sites must usually be transferred to the cache, rather than simply
the pages that the subscribers want to look at; there's no way to
predict which pages will be of interest.
All these developments have led to predictions of severe traffic
jams, even of Internet meltdowns.
I have a modest proposal. Within our present Web servers and
browsers, we already have the tools to overcome the traffic jam. I
propose that one day a month - say from midnight on the first
Sunday of each month to midnight Monday, Greenwich Mean Time -
everybody using the Web should agree to turn off graphics and
limit their serving and browsing to text-only. Real-time audio,
Internet telephone conversations, video conferencing, and other
bandwidth hogs can wait for a day. With only text traffic, the
speed of the Internet should increase spectacularly.
Of course graphics serve an important function, so graphics that
the user specifically asks for will be served. What will be banned
are the gratuitous graphics that the user does not specifically
request. Why does any Web page have a background pattern, anyway?
The backgrounds simply clog up the works without adding any
information. No one would put up with a book that had intrusive
patterns on the page. Many Web page have large, useless graphics
that serve no function except to take up time. How many times have
you waited out the endless download of some stylized logo for a
company whose name you already know? After all, you selected their
Web page.
With my proposal, for at least for one day a month we can get some
work done on the Internet. For the rest of the month, it's
molasses as usual.
Some simpler steps might be taken by browsing software. Browsers
should have settings so that they automatically won't download
graphics over an adjustable size. HTML tags should separate
essential from optional graphics, although this would require some
discipline on the part of Web page designers, the very group
responsible for many of the interminable waits.
Some people will argue that my proposal is impossible; Internet
users as a group will never agree to text-only Mondays. Maybe. But
think about this the next time you need to find some information
on the Web.
Getting Through the Media Blitz
-------------------------------
by Chad Magendanz <ch...@halcyon.com>
[With Apple's recent flood of software releases and updates,
TidBITS has been receiving a number of questions about disk
images: what they are, how to use them, and where they came from.
Since few people know more about disk images than Chad Magendanz
(author of the widely-acclaimed disk image utility ShrinkWrap),
when Chad volunteered to write an article on the subject, we took
the opportunity to chain him to his keyboard, crack our whips, and
get a definitive run-down on disk images and disk image software.
Enjoy! -Geoff]
At the most basic level, a disk image is simply a file that
contains a verbatim copy of every sector from a disk. Although
disk images of floppy disks are by far the most common, the
concept applies to disks of any size. As the cost of high-capacity
storage has decreased, people have been using disk images for more
than distributing system updates. Mac users are finding it
increasingly difficult to justify hanging on to the hundreds of
floppies when they can preserve images of these floppies neatly on
high-capacity, removable media. After all, when one CD-R disk can
easily hold over a thousand compressed floppy disk images, it
suddenly becomes realistic to carry your complete software archive
wherever you go.
**Exposing An Image** -- Disk images ensure that everyone receives
the same material electronically that they would receive if they
were handed a floppy disk. You can think of a disk image as a
temporary scratch file that allows for time-delayed disk
duplication: you simply run a disk image utility to recreate the
original disk. To ensure that the disk reproduces correctly, disk
images contain checksum values. Checksum values are virtually
unique "signatures" generated from a disk's content; since the
odds of two disks having different data and the same checksum
value are astonishingly low, checksums are an efficient way of
making sure disks are identical.
When copying a floppy disk, it doesn't always work well to drag
the disk's contents to a different disk or to a folder. A disk
duplicate made from an image file is an _exact_ duplicate, whereas
a disk copy made by dragging icons is not. Disks created from
image files duplicate their originals exactly, including icon
placement, window appearance, and the disk name. Disk images offer
the added assurance that all files have duplicated correctly and
completely. More importantly, many installers fail to recognize
disks copied by dragging icons, even if these disks appear
identical to their originals.
**The Virtual Volume** -- Originally, an obvious drawback to image
files was that you had to copy an image file back to a real floppy
disk to use it, an annoying and time-intensive process.
Fortunately, there are now several reliable utilities that enable
Mac users to mount disk images on the desktop as virtual floppy
disks. These utilities allow the system to think that an actual
floppy disk has been inserted, and some even allow you to mount
images as unlocked volumes so you can make and save changes to the
image files.
In addition to allowing you to conduct a complete installation
without touching a floppy disk, mounted disk images offer several
less obvious but equally important applications. Think about it:
Macs without high-density SuperDrives (or PowerBooks with no
floppy drive at all!) can access any type of floppy if you can
make a disk image and transfer it via a network connection. You
can even use mounted disk images as temporary partitions like a
RAM disk, but unlike most RAM disks, volumes created from mounted
images can be created or destroyed at any time without restarting
your machine. Finally, the checksums generated for disk images can
be used to track changes made to media released for software
development, manufacturing, and distribution.
**Disk Image Utilities** -- The original disk image utility for
the Macintosh was Apple's DiskCopy, written by Steve Christensen
at least seven years ago. As the years went by and Apple's
original offering saw no significant updates, many new disk image
utilities (and new disk image file formats) began to appear.
Here's a chronological summary of utilities currently available:
* DiskCopy 4.2 by Steve Christensen from Apple. Steve used his
intimate knowledge of the SONY driver to make this one of the most
elegant and compatible applications ever packed into 24K. DiskCopy
4.2 is still the only disk image utility officially supported by
Apple.
<ftp://ftp.support.apple.com/pub/apple_sw_updates/US/mac/utils/
Disk_Copy_4.2.hqx>
* DART 1.5.3 by Ken McLeod from Apple. This utility went a step
beyond DiskCopy 4.2, adding interface improvements, simple drag &
drop functionality, and a new image file format that supported RLE
and LZH compression. Unfortunately, DART suffers from slow
performance compared to DiskCopy.
<ftp://ftp.support.apple.com/pub/apple_sw_updates/US/mac/utils/
DART_1.5.3.hqx>
* DiskCopy 5.0d1-6.0 by Steve Christensen (and "anonymous
contributors"). Based on a beta of DiskCopy 5.0 that was leaked to
the general public without Steve's consent, this application has
been lurking on BBS's for years, wearing several different version
numbers. Although they look and act much like DiskCopy 4.2, these
builds add support for two new image file formats, an RLE
compressed disk image and a self-extracting disk image that can
decompress and save itself to floppy disk. Use of these versions
of DiskCopy is discouraged since they're not supported by Apple
and the new image file formats they produce don't work with other
disk image programs.
* MountImage 1.2b2 by Steve Christensen. This control panel can
mount up to eight disk images on the desktop. Unfortunately,
MountImage has a serious bug that can cause data corruption if the
original image file is split into more than three fragments when
stored on disk. In this case, MountImage can lose track of some
data fragments, blindly reading and writing to blocks that may not
belong to the image file, which can overwrite and damage other
files on your drive. Use of MountImage is _highly_ discouraged,
even by Steve.
<ftp://mirror.aol.com/pub/info-mac/disk/mount-image-12b2.hqx>
* MungeImage 1.2 by Peter N Lewis and Quinn "The Eskimo."
MungeImage, a famous eight hour hack, works around MountImage's
fragmentation problem by loading disk images entirely into RAM. It
has a faceless drag & drop interface and can mount both DiskCopy
and DART images, although only DiskCopy images can be mounted as
unlocked volumes. Peter and Quinn have placed MungeImage's Pascal
source code (which includes descriptions of DiskCopy and DART file
formats) in the public domain.
<ftp://mirror.aol.com/pub/info-mac/disk/munge-image-120.hqx>
<ftp://ftp.share.com/pub/peterlewis/source/mungeimage-120-source.sit.bin>
* Norton Floppier 3.2. This disk duplication and formatting
component of Norton Utilities 3.2 only supports its own
proprietary disk image format, but does provide an option to copy
only used sectors.
* MacTools FastCopy 4.0. This component of MacTools Pro 4.0
provides the same functionality as Norton Floppier, but supports
Apple's DiskCopy image files and its own compressed image files
(which use Stacker's proprietary compression algorithm).
* DiskDup+ 2.7 by Roger Bates. This utility excels at disk
duplication, sporting options to ignore unused or bad blocks and
even copy 800K images onto 1.4 MB media with increased free space.
DiskDup+ supports reading and writing Apple DiskCopy images as
well as its own DiskDup+ image file format, and will mount image
files after you pay the $25 shareware fee. Roger also has a
commercial version called DiskCopy Pro that supports removable
media larger than floppies.
<ftp://mirror.aol.com/pub/info-mac/disk/disk-dup-plus-27.hqx>
* Disk Charmer 3.0.2 by Fabrizio Oddone. This $10 shareware
utility's claim to fame is its ability to read, write, and format
floppy disks in the background using asynchronous I/O and the
Thread Manager. Copies take a little longer, but the ability to
switch to another application and perform another task while you
read or write DiskCopy disk images can be a real boon.
<ftp://mirror.aol.com/pub/info-mac/disk/disk-charmer-302.hqx>
* ShrinkWrap 2.0.1. (I know this is my own program, but I never
claimed to be unbiased!) This utility reads, writes, mounts, and
converts a variety of images files for volumes of all sizes,
including new self-mounting image files that can mount or save
themselves back to disk. Designed around a drag & drop interface,
ShrinkWrap also provides an menu-driven front end and a full-
featured Apple event suite. It handles integrated compression,
encryption, and encoding through Aladdin's StuffIt Engine and has
a batch mode that speeds large jobs. ShrinkWrap is freeware, but
with a $20 shareware fee for commercial use.
<http://www.halcyon.com/shrinkwrap/>
<ftp://mirror.aol.com/pub/info-mac/disk/shrink-wrap-201.hqx>
* CryptDisk 1.2.1 by Will Price. This $20 shareware tool is
designed for disk image users who take encryption _very_
seriously. Although CryptDisk doesn't read or write image files to
disk, it does create and mount soft partitions of any size that
are encrypted using IDEA (International Data Encryption Algorithm)
encryption. IDEA uses 128-bit keys and is generally recognized as
secure. The full version of CryptDisk is available for U.S. and
Canadian citizens; a demo without encryption is available to
anyone.
<http://www.primenet.com/~wprice/cdisk.html>
* DropDisk 1.0b5 by Chris Cotton and Mike Wiese. Originally
released as Mount 'em, Chris and Mike leveraged much of the work
done to mount PC drive containers for Apple's DOS card with PC
Exchange to overcome the problem with fragmented disk image files
and mounting disk images from a network. However, the application
has only a drag & drop interface and can't mount DiskCopy images
unlocked.
<ftp://ftp.info.apple.com/Apple.Support.Area/Developer_Services/Utilities/
DropDisk.sit.hqx>
* Disk Image Mounter 1.0.1 by Apple. This direct descendent of
DropDisk was given a simple front end, modified to support New
Disk Image Format (NDIF; see below) images and DiskScripts (batch
files for mounting disk image sets), then packaged with the
PowerBook 5300s. It only supports mounting disk images as unlocked
volumes.
<ftp://ftp.support.apple.com/pub/apple_sw_updates/US/mac/utils/
Disk_Image_Mounter_1.0.1.hqx>
* DiskCopy 6.0.1 by Byron Han for Apple. DiskCopy 6.0.1 will be a
complete rewrite of DiskCopy, supporting copying, creating,
converting, and mounting DiskCopy 4.2 and NDIF disk images. It
will also add support for AppleScript, log files, CRC-32
checksums, DiskScripts, and digital signatures. Currently,
DiskCopy 6.0.1 is currently only available for Apple internal use.
**Some Fuzzy Images** -- I should point that some installers don't
play well with disk images: the most notable are from Microsoft
and Connectix. Many of Microsoft's installers simply don't check
if the next disk is available before ejecting the current disk and
prompting the user to insert a floppy. Of course, "reinserting" a
mounted disk image from a modal dialog is practically impossible.
Connectix's installer, on the other hand, is clever enough to
determine if it's being run from a physical floppy disk and forces
the user to quit if that's not the case, probably as an attempt to
deter piracy. Of course, you can work around these installers by
copying disk images to floppy disks and running the installer the
old fashioned way, but that's not as convenient.
Additionally, developers usually take two approaches to mounting
disk images: RAM-based and file-based. A file-based driver mounts
image files by accessing blocks directly from a local hard drive
or a network server; conversely, a RAM-based driver mounts an
image file by dynamically creating a RAM disk and then copying the
contents of the image file to the RAM disk. Although the RAM disk
eventually makes for faster performance, mounting the image takes
longer and you must always have as much free RAM as disk capacity
you wish to mount. (Sorry - virtual memory doesn't count!) File-
based drivers typically use only about 1K of RAM per mounted
image, but they're slower and can be confused by background
compression utilities like AutoDoubler or StuffIt SpaceSaver.
Currently, all the utilities mentioned above except MungeImage use
file-based drivers, although ShrinkWrap supports both techniques.
Versions of Apple's DiskCopy prior to 6.0.1 have a problem with
occasionally incorrectly calculating checksums for tag data. Tag
data is an extra 12 bytes of "scavenger" information for each
block on 400K and 800K floppies. It was mainly used to embed copy
protection information and data recovery hints back in the old
days of half-tracking and other such whimsical annoyances. Since
the 660AV and 840AV Macs can't even read tag data, many disk image
utilities and disk image formats safely ignore it.
**New Disk Image Format** -- With the glut of alternative disk
image file formats available, you may find it surprising that the
original DiskCopy format still dominates online. Well, aside from
the disadvantage of having to compete with the officially endorsed
Apple image file format, many of the "improved" image file formats
fall short of DiskCopy in critical areas. For example, compressed
image files or images that don't contain copies of unused blocks
can't be mounted on the desktop as unlocked volumes. What's more,
many simplified file formats lack critical information like
checksums and tag data that may be critical to identifying data
loss or satisfying some copy protection schemes.
However, there are some simple ways the present DiskCopy image
file format can be improved, and the New Disk Image Format (NDIF)
supported in Disk Image Mounter 1.0.1 and DiskCopy 6.0.1 is
Apple's attempt to do just that. This new file format comes in
three flavors, Read/Write, Read-Only, and Read-Only Compressed,
enabling the user to optimize the image file for flexibility,
speed, or size. All NDIF flavors use industry standard CRC-32
checksums, and none waste space saving tag data.
Unfortunately, all the advantages of the NDIF format are offset by
the fact that it presently only uses one compression scheme, an
Apple proprietary codec named KenCode. Because of this
restriction, no other commercial, shareware, or freeware utilities
can legally read or write NDIF compressed image file formats
without licensing the KenCode libraries from Apple. There have
been overtures from Apple promising these libraries will be
released to the general public at no charge, but I've seen no
progress in this effort since November of 1995.
**Your Mission** -- Has the time come to throw away your floppies?
For many Mac users, the answer is definitely yes. One batch
session with a good disk image utility can reduce a rat's nest of
floppy disks to a manageable archive on removable cartridge or
CD-ROM that you can take on the road and share over local networks
or the Internet. Software installations from mounted disk images
can save countless hours, especially for MIS managers, testers,
and service technicians who configure new machines daily. So, find
a utility that suits your tastes and discover the power of disk
images!
$$
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