Macintosh 128K upgrades

Turns a spare compact-Mac logic board into a small desktop computer with modern power, display, and storage hardware.

For this system (exact model): JCM sells a 128K/512K enclosure and GutBomb includes the 128K in the printable design. A complete build needs the donor logic board plus model-appropriate power, video, storage, input, and display hardware.

On 2026-07-24 JCM showed 5 printed 128K/512K cases, 3 Plus cases, 2 SE/SE30 cases, and 5 Classic/Classic II cases in stock. This is an enclosure, not a complete computer: supply a working logic board, power and video electronics, storage, input devices, display, cabling, and other desired parts. GutBomb's printable design is CC BY-NC-SA and does not cover the separate electronics.

Replaces missing or broken case-mounted programmer's switches on compact Macintosh computers.

For this system (exact model): The Macintosh 128K is explicitly named. Install without forcing the resin replacement.

Both product pages said Sold out or Out of Stock on 2026-07-27. The Greeny-switch resin can break if excessive force is applied. Choose the model-specific variant; neither seller establishes cross-family interchangeability between the early compact-Mac and SE-family switch assemblies.

Uses an SD card to emulate Apple floppy drives and, on supported systems, HD20 or SmartPort hard disks.

For this system (stated family): The manual's Macintosh compatibility scope begins with the original Macintosh 128K. Install the Macintosh/Lisa firmware and use the supplied DB-19 adapter or the documented internal connection. Confirm the supported 400K floppy mode and disk-image format before use.

The BMOW store showed the assembled Model C sold out at $109 on 2026-07-27. The separate Deluxe bundle is the same emulator packaged with accessories rather than a different product family. Check the direct product page for a restock.

Current and buildable replacement ROMs for early compact Macs with a customizable bootable ROM disk and HD20 support.

For this system (exact model): The current kit offers a Macintosh 128K ROM set with a System 3.2 ROM disk. Some software may identify a ROM-inator-equipped 128K as a Macintosh Plus.

On 2026-07-24 JCM showed eleven 128K/512K modules and nine Plus modules in stock. Infinity Products also listed standard and spare-ROM kits without an out-of-stock marker. Installation requires opening the Macintosh, removing its ROMs, and soldering three or four address and write lines to the mainboard. BMOW provides the original parts list, Gerbers, assembly instructions, Flash Tool, and ROM data.

Adapts modern USB keyboards and mice to early Macintosh keyboard and mouse ports or to ADB.

For this system (exact model): Uses the early Macintosh RJ11 keyboard and DB9 mouse interfaces. Both require dedicated straight-through cables; ordinary crossover telephone cable will not work.

The current page listed a fully assembled unit without an out-of-stock marker on 2026-07-24. Firmware and hardware are closed source. USB peripheral and hub compatibility varies; early iMac Rev. A through C USB keyboards are explicitly unsupported.

Converts raw compact-Mac video to VGA, with optional power integration for bare logic-board projects.

For this system (exact model): The standalone MacPicoVid boards explicitly list the Macintosh 128K and require separate 5 V USB power plus raw video and sync wiring. A power-integrated CatMac build instead uses the SE-COMBO with JCM's 128/512/Plus J8 adapter.

On 2026-07-24 JCM showed 11 onboard-VGA and 41 Extended MacPicoVid boards, 56 MacPicoVid SE-COMBO boards, 2 IDC12 boards, 19 SE-TOPPER boards, 46 128K/512K/Plus adapters, and 32 Classic adapters in stock. Standalone boards require separate 5 V USB power and host wiring. The power-integrated products are for a removed logic board or custom chassis, not a drop-in external-video port for an intact computer.

Open, reversible Pico ATX power-adapter family for the Macintosh 128K, 512K, Plus, SE, and SE/30.

For this system (exact model): The early compact-Mac adapter explicitly supports the Macintosh 128K and plugs into the logic board to bypass the original AC/DC power conversion. Follow the project instructions, use the correct cable routing and fuse values, and observe compact-Mac CRT high-voltage precautions.

On 2026-07-27, the 128K/512K/Plus listing showed order controls at $29.99 and the SE/SE30 listing showed order controls at $34.99. Both offered kit and assembled choices. Their United States shipping sections simultaneously displayed rates and a does-not-ship warning, so confirm destination availability at checkout. A suitable PicoPSU and adequately rated 12 V center-positive power brick are separate parts.

Switches an upgraded early Macintosh between 128K and 512K memory configurations.

For this system (exact model): All sixteen DRAMs must first be replaced with 41256 devices for 512K. Installation uses the E3 footprint and requires cutting the specified connection between pins 1 and 2.

The product page listed the switcher kit and optional Macintosh 512K adapter without an out-of-stock marker on 2026-07-24. The vendor no longer sends this electronic item by international registered mail.