Macintosh IIsi upgrades

Adds external VGA to an SE/30 or IIsi, with selected SE/30 variants also driving the internal CRT in grayscale.

For this system (exact model): The 30Video SI and current external-only branches explicitly support the IIsi with the model-specific PDS connector. Internal SE/30 grayscale and LCD hardware does not apply to the IIsi.

Juicy Crumb showed the complete $949 SE/30 Greyscale Kit out of stock on 2026-07-27, and the developer page exposed no separate public order path for current external-only cards. The nonstandard 1024 by 768 at 54 Hz mode will not sync on every display. Extra PDS cards can cause instability, and the maker warns that adapting VGA output to a vintage Apple CRT may damage the monitor.

Single 16 MB, 60 ns, non-parity fast-page-mode SIMM for specifically listed 30-pin Macintosh systems.

For this system (exact model): The seller explicitly lists the Macintosh IIsi and requires four modules for Macintosh use. Confirm bank population, ROM support, and physical clearance.

The Artmix product page reported out of stock on 2026-07-24. Check the direct page for a restock and confirm the exact computer's ROM, addressing, bank-population, and clearance requirements.

Visualizes Macintosh PDS signals with LEDs and provides a pass-through plus a right-angle test connector.

For this system (exact model): The product page explicitly names the Macintosh IIsi. Use it as an external troubleshooting tool and verify slot IDs, power load, physical clearance, and card-to-card compatibility before attaching two PDS devices.

The Juicy Crumb page showed BlinkenPDS in stock on 2026-07-24. It is a bench development tool and is not intended for permanent in-case use; the maker says it fits poorly inside a computer. The second connector does not establish that arbitrary pairs of PDS cards are electrically compatible.

Open hardware SCSI emulator with SD-backed storage, optional Wi-Fi networking, and host-side management tools.

For this system (exact model): The official documentation lists the IIsi with caveats; confirm termination power and supply external USB power if the selected setup needs it.

Current seller checks on 2026-07-27 found a $39 internal 50-pin Pico 2 W kit, a $49 assembled external DB-25 model, a $49 PowerBook model, and a $59 assembled Ultra Narrow 50-pin model at authorized seller ToTs RETRO. JCM also carried assembled Ultra hardware and model-specific Macintosh adapters. Prices, stock, included media, and support differ by seller. Ultra models require Berg or Molex power and cannot run from SCSI termination power. The initial Ultra hardware release is not yet open hardware, although its firmware remains GPL; the project says hardware licensing will open later.

Open 64-pin ROM SIMM with selectable 32-bit-clean System 6 and System 7.1 ROM disks for six 68030 Macintosh models.

For this system (exact model): The IIsi is explicitly supported. Use either custom image or the unmodified IIsi ROM; the supplied unmodified IIx ROM is not compatible with this model.

The assembled Tindie module was out of stock on 2026-07-24 and had been sold out since May 7, 2025. Hardware, software, and fabrication files remain public. Most tested 68030 accelerators work, but some 68040 accelerators do not; select the stock IIsi or IIx ROM when the custom image is incompatible. Only 8 MB of the 16 MB flash can be selected at once, with the computer powered off before changing the switch.

Replace a Macintosh ROM SIMM with reprogrammable flash for custom ROMs and, with 2 MB of flash, a bootable ROM disk.

For this system (exact model): The product listing and project documentation explicitly support the Macintosh IIsi as a programmable replacement ROM SIMM.

The GGLABS Tindie store was taking a break on 2026-07-27, but EconoSimm remains buildable from published files. EconoSimm requires a roughly 1.2 mm PCB so it fits the ROM socket, four compatible PLCC-32 flash chips, and a standard flash programmer with a PLCC32-to-DIP adapter. Its author says the BMOW SIMM programmer may work but has not tested it. The bootable 1.5 MB ROM disk requires 2 MB of flash and a correctly prepared image.

Adds bootable CompactFlash storage through the PDS, bypassing the original SCSI implementation.

For this system (exact model): The maker explicitly supports the IIsi. Its version has a straight top PDS connector and normally uses slot ID D. The SE/30 connector version prevents the IIsi case from closing unless it is used with an IIsi Booster 2.0.

The maker states that production is on hold with no ETA. The public support repository contains firmware and installation files, but no DIY hardware fabrication package.

Connects modern USB HID keyboards and mice to Macintosh computers through Apple Desktop Bus.

For this system (bus/interface): The IIsi provides Apple Desktop Bus for its keyboard and mouse, and Rabbit Hole specifies QuokkADB for any ADB-equipped Macintosh.

HIDHopper Base, Base with USB Hub Hat, and Hub Hat-only selections could be added to the JCM cart on 2026-07-24. The assembled QuokkADB Rev. 2022g remained sold out, while its Raspberry Pi Pico Community Edition remained buildable. HIDHopper's Hub Hat requires external USB-C power, must be power-cycled between Macintosh starts, and can otherwise exceed the host's ADB power budget.

Provides a programmable 2 MB Macintosh ROM SIMM using four socketed PLCC32 flash chips.

For this system (exact model): The IIsi is explicitly named. A SIMM socket may need to be installed on systems that lack one.

The current page offered populated and chipless versions in multiple PCB colors on 2026-07-24. Its dated notice says the red PCB alone was out of stock on 2026-04-26, with black and purple also listed.

Open-firmware SCSI emulators in DB-25, internal 50-pin, laptop, and Wide SCSI form factors.

For this system (bus/interface): The product is designed for direct attachment to any DB25 SCSI host, and the IIsi provides external DB25 SCSI. A Pico Slim must be the final device because its termination cannot be disabled; use USB power if the SCSI chain does not supply termination power.

Rabbit Hole Computing offered current Compact RP2040, Blaster, and Wide variants on 2026-07-24. A 2026-07-27 follow-up found its mostly assembled $25 Pico Slim V1.3 PCB kit sold out, while SamplerZone exposed an Add to Cart path for a $79.95 assembled and cased Pico Slim with configured microSD media. Rabbit Hole's direct Pico2 Slim and Laptop Blaster pages were also sold out. TinySCSI was archived in January 2025, but its V1.0 and V2.0 KiCad files remain available for personal builds. A project discussion documents Wi-Fi DaynaPORT operation on a Pico Slim under System 7.5.5 with the DaynaPORT SCSI-port driver, but does not establish a minimum System version or equivalent networking support for every family variant. Connector, termination, power, speed, and initiator support vary by hardware.