Macintosh IIsi Macintosh IIsi

Macintosh IIsi Explained

In the ever-evolving world of personal computing, there are products that become iconic for their groundbreaking features or significant contributions to the industry. On October 15th, 1990, Apple introduced the Macintosh IIsi, a personal computer that holds a special place in the history of technology.

While it may not have achieved the same level of fame as some of its predecessors, the IIsi remains an important artifact, showcasing the evolution of personal computing during its two-year production span. Join us as we explore the key features, legacy, and enduring significance of the Macintosh IIsi.

The Macintosh IIsi was part of the Macintosh II series and was designed to be a more affordable alternative to the Mac IIci. Sporting a compact and curved front, reminiscent of the LC series, the IIsi shared similarities with other Macintosh models. It featured a 20 MHz Motorola 68030 processor, a Motorola 68882 FPU coprocessor, and offered either 2 MB or 5 MB of RAM. Storage options ranged from a 40 MB or 80 MB hard drive to a spacious 160 MB capacity. The inclusion of a 1.44 MB floppy drive and an optional Macintosh II video card added to its versatility.

While marketed as a 20 MHz computer, users soon discovered that the IIsi utilized parts capable of operating at 25 MHz. Apple had initially intended it to be a 25 MHz machine but scaled back its speed to avoid cannibalizing sales of the more expensive IIci model. Interestingly, many tech enthusiasts found ways to “chip” the IIsi, pushing its performance to 25 MHz or even 28 MHz, showcasing the potential hidden beneath its modest exterior.

The Macintosh IIsi had some distinctive characteristics that set it apart from other Macintosh models of its time. Similar to the IIci, it relied on onboard RAM for video, resulting in slightly slower performance. However, users could enhance the system’s speed by adding a PDS or NuBus video card. Another workaround involved setting aside the first 1 MB of RAM, shared for video and program space, by creating a disk cache or utilizing specialized software.

Audio input capabilities were one of the notable features of the IIsi, placing it alongside the LC as one of the first Macs with this functionality. However, some users encountered a sound issue where the internal speaker failed to produce audio. Cleaning and coating the contacts on the motherboard proved to be a reliable fix for this problem, bringing back the missing sound.

Despite being discontinued on March 15, 1993, the Macintosh IIsi has secured its position as a vintage device and an essential part of computing history. Its place within the Macintosh lineup showcased Apple’s efforts to offer affordable options while providing a glimpse into the advancements and compromises of that era. The IIsi’s compact design and cost-saving measures allowed a wider audience to experience the power of Macintosh computing.

The Macintosh IIsi’s impact can be seen in the continued fascination with vintage Macs and the dedicated communities that preserve and celebrate these devices. Today, 33 years later enthusiasts still can find support, knowledge, and camaraderie through online forums and groups dedicated to vintage Macs. The IIsi serves as a tangible reminder of the significant milestones in the evolution of personal computing.

The Macintosh IIsi may have been a “Compromised Mac” in certain respects, but it holds a unique place in the annals of computing history. Introduced in 1990 at a starting price of $3,770, this personal computer offered a glimpse into the past, showcasing the technical trade-offs that were made to deliver an affordable yet powerful machine. The IIsi’s enduring legacy and its contributions to the advancement of personal computing make it a cherished piece of vintage technology, keeping the spirit of innovation alive for generations to come.

Mac IIsi
Source: – Mac IIsi

Macintosh IIsi Details

IntroducedOctober 15, 1990
DiscontinuedMarch 15, 1993
Model Identifier18
Model NumberM0360
Order NumberM0363LL/A
Original Price$3,770
Weight10 Ibs.
4.535 KG
Dimensions4” H x 12.4” W x 14.9” D
10.16 cm H x 31.49 cm W x 37.84 cm D

Mac IIsi Tech Specs


ProcessorMotorola 68030
Processor Speed20 MHz
Number of Cores1
System Bus20 MHz
Cache0.5 KB L1
CoprocessorMotorola 68882 FPU (Optional)

Storage & Media

Storage40 MB
80 MB
160 MB
Media1 – 1.44 MB Floppy


Built-in Memory2 MB
5 MB
Maximum Memory65 MB
Memory Slots4 – 30 pin SIMMs (Groups of 4)
Minimum Speed100 ns
Interleaving SupportNo


Built-in DisplayNone


Graphics CardNone
Graphics Memory64 – 320 KB (Shared system RAM)
Display Connection1 – DB-15


Expansion Slots1 – NuBus or Cache Bus (PDS)
Hard Drive InterfaceSCSI


SCSI1 – DB-25
Floppy Port1 – DB-19
Audio In1 – 3.5-mm nano input jack
Audio Out1 – 3.5-mm stereo output jack
Display1 – DB-15


Original OSSystem Software 6.0.6
Maximum OSMac OS 7.6.1
FirmwareMacintosh ROM


Backup Battery3.6 V lithium
Maximum Continuous Power160 W
Line VoltageUnknown

Further Reading and References

Disclaimer: The data presented in this article is under continuous development and has been manually collected from various sources based on their availability. The author of this article may revise this dataset as additional research is conducted and reviewed. Please note that the information is provided “as is” and “as available” without express or implied warranties. The author cannot be held responsible for any omissions, inaccuracies, or errors in the published information. Any warranties relating to this information are hereby disclaimed.

Last updated: May 22, 2023