The Apple Network Server was designed to run Harpoon, Apple’s AIX-based Unix, but its Power Macintosh 9500 roots and recovered preproduction ROM make it possible to boot classic Mac OS as well. That ROM preserves AIX booting and L2-cache support, unlike a later Mac OS ROM, but initially lacks working onboard video and MACE Ethernet and can fail on restart. The author’s first software release addresses those problems, enabling onboard graphics, Ethernet and reliable Mac OS restarts while retaining the machine’s original AIX capability. The setup uses the 1.1.20.1 preproduction ROM, Mac OS installed on an external SCSI disk, and, depending on the installation method, a compatible PCI video card and bootable CD. Mac OS versions through 9.1 can boot directly; the author recommends 8.1 or later.
The technical explanation focuses on how PCI Power Macs load device drivers, and why the fixes can be implemented as native extensions. Classic Mac OS relied heavily on 68K drivers, while Apple’s unfinished Copland project introduced PowerPC-native drivers linked to a hardware abstraction layer and a Name Registry. Elements of that architecture carried into PCI-era Macs: Open Firmware builds a device tree, ROM code registers devices, and matching native drivers in the Extensions folder can load early in startup. The ANS’s registry includes not only PCI cards but also onboard components such as its processor, cache, SCSI, sound and Ethernet hardware. This framework provides the means to address the ROM’s missing support in software rather than changing the hardware or giving up AIX compatibility.
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