Macintosh IIsi
Manufacturer	Apple Computer
Type	{{{Type}}}
Casing	{{{Casing}}}
Introduced	October 15, 1990
Discontinued	March 15, 1993
Price	US$2999
CPU	Motorola 68030, 20 MHz
RAM	1 MB, expandable to 17 MB, 100 ns 30-pin SIMM
OS	System 6.0.7

Macintosh IIsi rear showing ports, including 10base2, 10baseT and AUI ethernet card.

The Macintosh IIsi was a compact 3-box desktop unit, effectively a cut-down Macintosh IIci in a smaller case, made cheaper by the redesign of the motherboard and the deletion of all but one of the expansion card slots (a single Processor Direct Slot). It was introduced as a low-cost alternative to the professional desktop models for home use, but offered more features and performance than the LC series. It had color and could drive a number of different external monitors, with a maximum screen resolution of 640 x 480 in 8-bit color. Image File history File links Download high resolution version (1024x607, 151 KB) Summary Macintosh IIsi, from original photography by myself. ... Apple Computer, Inc. ... October 15 is the 288th day of the year (289th in leap years). ... This article is about the year. ... March 15 is the 74th day of the year in the Gregorian Calendar (75th in Leap years). ... 1993 (MCMXCIII) was a common year starting on Friday of the Gregorian calendar and marked the Beginning of the International Decade to Combat Racism and Racial Discrimination (1993-2003). ... Motorola 68030 Processor from a Macintosh IIsi The Motorola 68030 is a 32-bit microprocessor in Motorolas 68000 family. ... Image File history File links Download high resolution version (1024x480, 156 KB) Summary The rear of a Macintosh IIsi. ... Image File history File links Download high resolution version (1024x480, 156 KB) Summary The rear of a Macintosh IIsi. ... The Apple Macintosh IIci was an improvement on the Macintosh IIcx. ... Processor Direct Slot or PDS, was a solution (actually, a whole number of different solutions) introduced by Apple Computer, in several of their Macintosh models, to providing a limited measure of hardware expandibility, without going to the expense (in both desktop space and selling price) of providing full-fledged bus... Macintosh LC sans display, keyboard or mouse The Macintosh LC (meaning low-cost color) was Apple Computers product family of low-end consumer Macintosh personal computers in the early 1990s. ...

It shipped with either a 40 MB or 80 MB internal hard disk, and a 1.44 MB floppy disk drive. The MC 68882 FPU was an optional extra, mounted on a special plug-in card. Ports included SCSI, two serial ports, an ADB port, a floppy drive port, and a microphone/sound input socket. The Motorola 68881 was a floating-point coprocessor chip that was utilized in some computer systems that used the 68020 or 68030 CPU. The addition of the 68881 chip added substantial cost to the computer, but added a floating point unit that could rapidly perform floating point math calculations. ... A floating point unit (FPU) is a part of a CPU specially designed to carry out operations on floating point numbers. ... SCSI stands for Small Computer System Interface, and is a standard interface and command set for transferring data between devices on both internal and external computer buses. ... Early ADB device Apple Desktop Bus (or ADB) is an obsolete bit-serial bus for connecting low-speed devices to computers. ...

A bridge card was available for the IIsi to convert the Processor Direct slot to a standard internal NuBus card slot, compatible with the other II-series Macintoshes. NuBus is a 32-bit parallel computer bus, originally developed at MIT as a part of the NuMachine workstation project, and eventually used by Apple Computer and NeXT Computer. ...

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 faster RAM installed in the SIMM banks. David Pogue is a New York Times technology columnist and author of several books on Macintosh-related topics including Macs for Dummies and Macworld Macintosh Secrets, later Macworld Mac and Power Mac Secrets, an enormous book on the Macintosh, circa 1993. ... 30- (top) and 72-pin (bottom) SIMMs. ...

The IIsi also suffered from sound difficulties - over time, the speaker contacts would begin to fail and sound would periodically drop out.

Because of its heritage as a cut down IIci, a simple modification carried out by many owners was to substitute a new clock crystal to bump the speed to 25 MHz. A wall clock A clock (from the Latin cloca, bell) is an instrument for measuring time and for measuring time intervals of less than a day—as opposed to a calendar. ... A crystal oscillator (sometimes abbreviated to XTAL on schematic diagrams) is an electronic circuit that uses the mechanical resonance of a physical crystal of piezoelectric material along with an amplifier and feedback to create an electrical signal with a very precise frequency. ...