Mac-PPC Computers Now Offer Solid State RAM Upgrades
In a revolutionary move for the retrocomputing world, DosDude1, a respected figure in the community, has developed a hack that enables soldered RAM upgrades on PowerPC Macintosh computers. This long-awaited breakthrough has been met with excitement by enthusiasts and collectors alike.
The PowerPC Macintosh, designed with OS9 in mind, presents a unique challenge. Unlike WinTel machines, it does not have a BIOS, and its soldered RAM modules lack an SPD (Serial Presence Detect) EEPROM, making it difficult for the system to identify and utilize upgraded RAM.
DosDude1's hack addresses this issue by modifying the system's BootROM to include the correct memory configuration data. This is achieved by editing the machine’s BootROM image to update the "Boot Flash System Configuration Block," which holds custom configuration entries describing the soldered memory layout.
The key steps in DosDude1’s method include:
- Extracting the BootROM Image: Dump the BootROM EEPROM content from the motherboard.
- Locating and Editing the Configuration Block: Identify the hex offset corresponding to the number of soldered RAM chips (e.g., offset 0x5C) and modify the hex value to tell the system to recognize the additional soldered memory chips.
- Recalculating Checksums: After editing the configuration data, recalculate the checksums for the system to accept the modified firmware.
- Flashing the Modified BootROM: Write the edited BootROM back to the motherboard’s EEPROM. This can be done externally with an EEPROM programmer or directly on the machine using Linux’s utility.
With this hack, PowerPC Macs can correctly identify and utilize the upgraded soldered RAM without needing other software updates, effectively enabling soldered RAM upgrades that were previously thought impossible.
For instance, the iBook G3 can now be upgraded to accommodate four more 128 MB DIMMs, effectively maxing out its RAM. The board must have spare address lines or a way to bodge them in for successful RAM upgrades on PowerPC Macintoshes.
The source of this groundbreaking information about PowerPC Macintosh RAM upgrades can be found on r/VintageApple on Reddit. The hack utilizes a document discovered by LightBulbFun on "Boot Flash System Configuration Block." It's important to note that the RAM upgrades for PowerPC Macintoshes are not compatible with modern DDR5 memory, and the footprints for the RAM upgrades must match the existing ones on the PowerPC Macintosh board.
As we continue to celebrate this exciting development, we look forward to seeing more innovative hacks and upgrades in the retrocomputing community. The upgrade of 21st-century quality-of-life to old budget PowerPC Macintosh hardware is now a reality, and it's an exciting time to be a part of this vibrant community.
[1] DosDude1's YouTube video on the subject [2] LightBulbFun's post on "Boot Flash System Configuration Block" [4] DosDude1's Reddit post about the hack
- DosDude1's hack not only applies to PowerPC Macintosh computers, but it also extends to other gadgets running Linux, such as smartphones and various hardware devices, as it modifies system firmware using similar techniques.
- Enthusiasts who own smartphones based on Linux kernel might be intrigued by the possibility of altering their device's firmware, just as DosDude1 did with PowerPC Macintosh, to expand its hardware capabilities beyond what the original manufacturer intended.
- Additionally, this hack could inspire technology enthusiasts to investigate and develop creative solutions for other outdated devices in their hardware collections, such as hacking retro gaming consoles or modified Linux-based routers for advanced network configurations.
