Tag: rom simm

5 matching upgrades

Showing 5 products.

StatusProductWhat it doesCompatibilityLinks
Build itChecked Jul 24, 2026GW4402B 8 MB ROM SIMMby Garrett's Workshop
rom simmflash rom32 bit cleanboot romrom diskopen hardwarediy

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

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.

Sources
  • Macintosh SE/30 Exact model
  • Macintosh IIx Exact model
  • Macintosh IIcx Exact model
  • Macintosh IIci Exact model
  • Macintosh IIsi Exact model
  • Macintosh IIfx Exact model
GW4402B product pageOpen hardware and ROM softwareGarrett's Workshop documentation
AvailableChecked Jul 14, 2026ISP-SIMM USB Programmable ROMby ZigZagJoe
rom simmprogrammable romusbflashrp2040firmware

Provides two switchable 8 MB flash banks that can be programmed over USB without a separate ROM programmer.

Sources
  • Macintosh SE/30 Exact model
Vendor product page
Sold outChecked Jul 14, 2026Mac ROM-inator II Carbonby Big Mess o' Wires
rom simm32 bit cleanboot romhd20memory

Replaces the stock ROM SIMM with a 32-bit-clean flash ROM, bootable ROM disk, and HD20 support.

The BMOW store showed the Carbon SIMM as sold out on 2026-07-14. It is incompatible with DayStar PowerCache and Turbo accelerators.

Sources
  • Macintosh SE/30 Exact model
Vendor storeProject detailsInstructions
Build itChecked Jul 27, 2026MACSIMM and EconoSimm Programmable ROM SIMMsby GGLABS and fran-cap
rom simmflash rom32 bit cleanboot romrom disk

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

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.

Sources
  • Macintosh SE/30 Exact model
  • Macintosh IIsi Exact model
  • Macintosh IIfx Exact model
EconoSimm build filesVendor product pageOfficial hardware documentationROM disk image tutorial
AvailableChecked Jul 24, 2026SMC ROM SIMM Cardby Infinity Products
rom simm2mbflash romepromboot romprogrammable rom

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

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.

Sources
  • Macintosh SE/30 Exact model
  • Macintosh IIx Exact model
  • Macintosh IIcx Exact model
  • Macintosh IIci Exact model
  • Macintosh IIfx Exact model
  • Macintosh IIsi Exact model
SMC ROM SIMM product and programming page