Skip to content
Thoughtful, detailed coverage of everything Apple for 32 years
and the TidBITS Content Network for Apple professionals

Double Stuff

I’ve used Salient Software’s Disk Doubler since Macworld Boston last summer. It has worked completely as advertised, transparently compressing files to save precious hard disk space, and I suspect I’ve compressed over half of the files on my hard disk. My problem is that I collect freeware and shareware applications, thinking I might need them someday (my mother is an archivist, so I suppose it’s in my blood). I avoided compressing them in the past, but Salient just released a free upgrade to Disk Doubler that automatically expands applications, even when a compressed document is double-clicked from the Finder. This works well, because I don’t have to leave, say PageMaker, uncompressed just because I use it once a month. Now, when I open a PageMaker document, compressed or not, Disk Doubler automatically opens everything for me and compresses it all when I’m done. It’s like having a butler put away your toys when you’re done playing. Disk Doubler 3.1 has a few other features that help it stand out. It has a collection of icons for popular programs that it uses instead of the generic Disk Doubler icon for compressed files. So if you compress an Excel documents, Disk Doubler changes its icon to a version looking like the normal one with the addition of a small DD in the corner. Though not a major feature, this nice touch helps you better identify compressed documents. If you hold down the Shift key when selecting Compress… or Expand… for a single file, the menu changes to Compress To… or Expand To… and lets you specify where to put the resulting file. There are a few other features that I haven’t fully explored, such as XCMDs for HyperCard and Extensions for QuicKeys2, but I’m sure that some people will greatly appreciate them.

I have found speed to be a minor problem with compressing applications, and I sometimes wonder about the "transparent" part of the marketing when I watch all 900K of PageMaker expand. Salient has solved this problem by teaming up with Sigma Designs, a major video display system maker. Sigma Designs has come up with two boards, the DoubleUp board and the Bullet. Both boards perform lossless hardware compression, and the Bullet includes a 40MHz 68030 for IIci and IIsi hardware acceleration. Both boards will be bundled with Disk Doubler because of its excellent interface and will use a dedicated compression chip from Stac Electronics, a company best known for compression in the PC world. Stac has a PC board that does lossless hardware compression but must have decided not to mess with the Macintosh market.

I expect that the DoubleUp board will be extremely popular because it offers the same level of file compression as Disk Doubler (about 50%) but at speeds estimated at about 10 times faster than Disk Doubler on a IIcx. At that speed, you won’t notice the expansion time on smaller files. The best part is that its suggested retail list price is $229, which makes it eminently affordable when purchased at normal discount prices. DoubleUp should be available in February for NuBus Macs and later in the year for the Mac SE and possibly SE/30. If only I hadn’t filled my one slot with the Micron video board. Oh well, I guess I’ll have to buy another Mac to hold the DoubleUp card. 🙂

The Bullet is equally interesting, but with a retail price of $1999 and the limitation of working only on the IIci and IIsi, I doubt it will be as popular as the DoubleUp. Nonetheless, it sounds as though Sigma Designs has designed it well, since the Bullet has an optional slot for a math coprocessor – $199 extra – for the IIsi and includes a Processor Direct Slot for the IIsi as well, so you can still add another card, though it would be a tight fit. On the IIci, the Bullet fits in the cache card slot, so it doesn’t hog a NuBus slot. One way or another, the Bullet is the first accelerator board for any Mac model that combines hardware acceleration with lossless compression, a good combination for all you power users. Look for the Bullet to appear in March of 1991 at your friendly local purveyor of cool hardware.

Salient — 415/321-5375
Sigma Designs — 415/770-0100

Information from:
Lloyd Chambers, Salient
LChambers @ America Online
[email protected]
[email protected]
Sigma Designs propaganda

Related articles:
MacWEEK — 15-Jan-91, Vol. 5, #2, pg. 9
MacWEEK — 08-Jan-91, Vol. 5, #1, pg. 6

Subscribe today so you don’t miss any TidBITS articles!

Every week you’ll get tech tips, in-depth reviews, and insightful news analysis for discerning Apple users. For over 31 years, we’ve published professional, member-supported tech journalism that makes you smarter.

Registration confirmation will be emailed to you.