Macintosh IIsi

Macintosh IIsi

A Macintosh IIsi
Developer	Apple Computer, Inc.
Product family	Macintosh II
Release date	October 15, 1990 (1990-10-15)
Introductory price	US$2,999 (equivalent to $7,220 in 2024)
Discontinued	March 15, 1993 (1993-03-15)
Operating system	System 6.0.7 – Mac OS 7.6.1, with 68040 upgrade Mac OS 8.1
CPU	Motorola 68030 @ 20 MHz
Memory	1 MB, expandable to 17 MB (100 ns 30-pin SIMMs)
Dimensions	Height: 4 inches (10 cm) Width: 12.4 inches (31 cm) Depth: 14.9 inches (38 cm)
Weight	10 pounds (4.5 kg)
Successor	Macintosh Centris 610

Macintosh IIsi rear view, showing ports and optional Ethernet card with 10base2, 10baseT and AUI connectors

The Macintosh IIsi is a personal computer designed, manufactured and sold by Apple Computer, Inc. from October 1990 to March 1993. Introduced as a lower-cost alternative to the other Macintosh II family of desktop models, it was popular for home use, as it offered more expandability and performance than the Macintosh LC, which was introduced at the same time. Like the LC, it has built-in sound support, as well as support for color displays, with a maximum screen resolution of 640 × 480 in 8-bit color.

The IIsi remained on the market for two and a half years and was discontinued shortly after the introduction of its replacement, the Centris 610.

Hardware

The IIsi's case design is a compact desktop unit not used for any other Macintosh model, one of the few Macintosh designs that was used for a single model. Positioned below the Macintosh IIci as Apple's entry-level professional model, the IIsi's price was lowered by the redesign of the motherboard substituting a different memory controller and the deletion of all but one of the expansion card slots (a single Processor Direct Slot) and removal of the level 2 cache slot.

It shipped with either a 40 MB or 80 MB internal hard disk, and a 1.44 MB floppy disk drive. The Motorola 68882 FPU was an optional upgrade, mounted on a special plug-in card. Ports included SCSI, two serial ports, an ADB port, a floppy drive port, and 3.5mm stereo headphone sound output and microphone sound input sockets.

A bridge card was available for the IIsi to convert the Processor Direct slot to a standard internal NuBus card slot, compatible with other machines in the Macintosh II family. The bridge card included the 68882 FPU to improve floating-point performance. The NuBus card was mounted horizontally above the motherboard.

To cut costs, the IIsi's video shared the main system memory, which also had the effect of slowing down video considerably, especially as the IIsi had 1 MB of slow RAM soldered to the motherboard. David Pogue's book Macworld Macintosh Secrets observed that one could speed up video considerably if one set the disk cache size large enough to force the computer to draw video RAM from the faster RAM installed in the SIMM banks.

The IIsi also suffers from sound difficulties: over time, the speaker contacts can fail, causing the sound to periodically drop out. This problem was caused by the very modular construction of the computer, where the mono loudspeaker is on a daughterboard under the motherboard, with springy contacts. Speaker vibrations led to fretting of the touching surfaces. The problem could be solved by removing the motherboard and using a pencil eraser to clean the contacts of the daughterboard holding the loudspeaker. As the IIsi is the only Macintosh to use this case design, these issues were never corrected in a subsequent model. The IIsi was designed to be easily and cheaply manufactured, such that no tools were required to put one together – everything is held in place with clips or latches.

Because of its heritage as a cut-down IIci, it was a simple modification to substitute a new clock crystal to increase the system's clock rate to 25 MHz for a slight increase in performance and a large increase in video rendering speed.

Known users

Charles Bukowski was an enthusiastic user of the IIsi.

Timeline

Timeline of Macintosh II family models

<timeline> DateFormat=mm/dd/yyyy Define $end = 12/31/1993 Define $skip = at:end # Force a blank line Period = from:01/01/1987 till:$end Define $dayunknown = 15 # what day to use if it's actually not known ImageSize= width:600 height:auto barincrement:21 TimeAxis = orientation:horizontal PlotArea = right:5 left:5 bottom:80 top:0 Legend = orientation:vertical position:bottom columns:1 Colors = id:bg value:white id:macii value:rgb(0.8,1,0.8) legend:Macintosh_II_case id:maciicx value:rgb(0.8,0.9,0.85) legend:Macintosh_IIcx_case id:maciisi value:rgb(0.85,0.9,0.8) legend:Macintosh_IIsi_case id:maciivx value:rgb(0.75,0.85,0.6) legend:Macintosh_IIvx_case id:line value:rgb(0.2,0.2,0.2) id:lightline value:rgb(0.8,0.8,0.8) legend:Other_Macs id:lighttext value:rgb(0.5,0.5,0.5) BackgroundColors = canvas:bg ScaleMajor = gridcolor:lighttext unit:year increment:1 start:01/01/1987 ScaleMinor = gridcolor:lightline unit:month increment:3 start:01/01/1987 BarData = Barset:macii Barset:reference PlotData= width:15 textcolor:black barset:macii shift:(5,-5) anchor:from fontsize:s color:macii from:03/02/1987 till:01/15/1990 text:"Macintosh II" color:macii from:09/19/1988 till:10/15/1990 text:"Macintosh IIx" color:maciicx from:03/07/1989 till:03/11/1991 text:"Macintosh IIcx" color:maciicx from:09/20/1989 till:02/20/1993 text:"Macintosh IIci" color:macii from:03/19/1990 till:04/15/1992 text:"Macintosh IIfx" color:maciisi from:10/15/1990 till:03/15/1993 text:"Macintosh IIsi" color:maciivx from:10/19/1992 till:02/10/1993 text:"Macintosh IIvi" color:maciivx from:10/19/1992 till:10/21/1993 text:"Macintosh IIvx" barset:reference color:lightline from:start till:04/01/1987 text:"Plus" barset:break color:lightline from:04/01/1987 till:09/16/1988 text:"SE" barset:break color:lightline from:09/16/1988 till:01/01/1989 text:"IIc+" barset:break color:lightline from:01/01/1989 till:09/20/1989 text:"SE/30" barset:break color:lightline from:09/20/1989 till:10/01/1990 text:"Portable" barset:break color:lightline from:10/01/1990 till:10/01/1991 text:"LC" barset:break color:lightline from:10/01/1991 till:$end text:"Quadra" </timeline>

External links

• Macintosh IIsi teardown at ifixit.com