Description
Apple Hard Disk 20SC M2603 825-1338-A 20MB External SCSI DB-25 Macintosh HDD
The Apple Hard Disk 20SC is Apple Computer's original external hard drive for the Macintosh, introduced in the mid-1980s. It connects via SCSI using a standard DB-25 connector and supports daisy-chaining of additional SCSI devices — a common configuration in Mac workstation setups of the era. The unit houses a 20MB hard disk in a compact desktop enclosure with Apple's distinctive beige/platinum styling and rainbow Apple logo. No operating system is installed.
Specifications & What's Included
- Make: Apple Computer, Inc.
- Model: Hard Disk 20SC
- Model Number: M2603
- Part Number: 825-1338-A
- Storage Capacity: 20 MB
- Interface: SCSI
- Connector: DB-25 (two rear SCSI ports — supports daisy-chaining)
- Power: IEC AC inlet with rear rocker power switch
- Form Factor: External desktop enclosure
- Operating System: None installed
- FCC Class B certified; UL listed (visible on bottom label)
Applications
The Apple Hard Disk 20SC was designed for use with SCSI-equipped Macintosh computers, including the Mac Plus, Mac SE, Mac SE/30, Mac II, IIx, IIcx, and IIci. When it launched alongside the Mac Plus in 1986, 20MB represented substantial storage for a personal computer, and the 20SC quickly became the standard external storage solution for the early Mac ecosystem. Today these drives are sought by vintage Apple collectors, classic Mac enthusiasts, and anyone maintaining an original Mac Plus or SE system. The SCSI interface supports up to seven daisy-chained devices, making it easy to expand storage in a period-correct Mac setup. Note that SCSI termination must be properly configured when daisy-chaining multiple devices.
This Apple Hard Disk 20SC (Model M2603, P/N 825-1338-A) external SCSI hard drive has been tested, formatted, and wiped, and is in good working condition. All previous data has been securely erased; no operating system is installed. The enclosure shows light yellowing and minor surface wear consistent with its age — normal for vintage Apple hardware from this era. Both rear SCSI DB-25 ports and the IEC power inlet appear clean and undamaged. Please view our photo set and contact us if you have any questions.
Warranty Information
Additional Information
Brand: |
Apple |
Model: |
M2603 |
MPN: |
825-1338-A |
Type: |
External Hard Drive |
SKU: |
29090 |
Storage Capacity: |
20 MB |
Interface: |
SCSI |
Connector Type: |
DB-25 |
Form Factor: |
External Desktop |
Number of SCSI Ports: |
2 (DB-25, daisy-chain capable) |
Power: |
IEC AC inlet with rear power switch |
Compatible With: |
Apple Macintosh Plus, SE, Mac II, IIx, IIcx, IIci |
Country/Region of Manufacture: |
United States |
Seller Notes: |
Drive only; no OS installed. Tested, formatted, and wiped. |
Condition Notes: |
This Apple Hard Disk 20SC M2603 external SCSI drive has been tested, formatted, and wiped — in good working condition. No OS installed; all previous data securely erased. Light yellowing and minor wear typical for vintage Apple hardware. |
California Prop 65 Warning: |
WARNING: This product can expose you to chemicals including lead and lead compounds, and DEHP (a phthalate), which are known to the State of California to cause cancer and birth defects or other reproductive harm. Go to P65Warnings.ca.gov |