Old World ROM
Encyclopedia
Macintosh Toolbox
The Macintosh Toolbox is a set of application programming interfaces with a particular access mechanism. They implement many of the high-level features of the Mac OS. The Toolbox consists of a number of "managers," software components such as QuickDraw, responsible for drawing onscreen graphics,...
ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
chip, usually in a socket (but soldered to the motherboard in some models). All Macs prior to the iMac
IMac
The iMac is a range of all-in-one Macintosh desktop computers built by Apple. It has been the primary part of Apple's consumer desktop offerings since its introduction in 1998, and has evolved through five distinct forms....
use Old World ROM, while the iMac and all subsequent models until the introduction of the Intel-based EFI Models are New World ROM
New World ROM
New World ROM computers are Macintosh models that do not use a Macintosh Toolbox ROM on the logic board. Due to Mac OS X not requiring the availability of the Toolbox, this allowed ROM sizes to shrink dramatically , and facilitated the use of Flash memory for system firmware instead of the now more...
machines. In common use, the "Old World" designation usually applies to the early generations of PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
-based "beige" Power Macs
Power Macintosh
Power Macintosh, later Power Mac, was a line of Apple Macintosh workstation-class personal computers based on various models of PowerPC microprocessors that were developed, marketed, and supported by Apple Inc. from March 1994 until August 2006. The first models were the Power Macintosh 6100,...
(and sometimes the very first NuBus
NuBus
NuBus is a 32-bit parallel computer bus, originally developed at MIT as a part of the NuMachine workstation project. The first complete implementation of the NuBus and the NuMachine was done by Western Digital for their NuMachine, and for the Lisp Machines Inc. LMI-Lambda. The NuBus was later...
-equipped models), but not the older Motorola 68000
Motorola 68000
The Motorola 68000 is a 16/32-bit CISC microprocessor core designed and marketed by Freescale Semiconductor...
-based Macs; however, the Toolbox runs the same way on all three types of machines.
PCI Power Macs with an Old World ROM contain an Open Firmware
Open Firmware
Open Firmware, or OpenBoot in Sun Microsystems parlance, is a standard defining the interfaces of a computer firmware system, formerly endorsed by the Institute of Electrical and Electronics Engineers . It originated at Sun, and has been used by Sun, Apple, IBM, and most other non-x86 PCI chipset...
implementation, and a copy of the Macintosh Toolbox as an Open Firmware device. These machines are set to boot from this device by default, thus starting the normal Macintosh startup procedure. This can be changed, just as on New World ROM Macs, but with limitations placed on what devices and formats can be used; on these machines, particularly the early machines like the Power Macintosh 9500
Power Macintosh 9500
The Power Macintosh 9500 was a high-end Macintosh personal computer which was designed, manufactured and sold by Apple Computer from May 1995 until early 1997. It was powered by a PowerPC 604 processor, a second-generation PowerPC chip which was faster than the earlier PowerPC 601 chip...
, the Open Firmware implementation was just enough to enumerate PCI devices and load the Toolbox ROM
Macintosh Toolbox
The Macintosh Toolbox is a set of application programming interfaces with a particular access mechanism. They implement many of the high-level features of the Mac OS. The Toolbox consists of a number of "managers," software components such as QuickDraw, responsible for drawing onscreen graphics,...
, and these Open Firmware revisions have several bugs which must be worked around by boot loaders or nvramrc patches. The Open Firmware environment can be entered by holding the Command-Shift keys as well as the O and F keys.
All Power Macs emulate
Mac 68K emulator
The Mac 68K emulator was a software emulator built into all versions of the Mac OS for PowerPC. This emulator permitted the running of applications and system code that were originally written for the 680x0 based Macintosh models. The emulator was completely seamless for users, and reasonably...
an 68LC040 CPU inside a nanokernel; this emulator is then used to boot the predominantly 68k-based Toolbox, and is also used to support applications written for the 68k processor. Once Toolbox is running, PPC machines can boot into MacOS directly.
On all Old World ROM machines, once Toolbox is loaded, the boot procedure is the same. Toolbox executes a memory test, enumerates Mac OS devices it knows about (this varies from model to model), and either starts the on-board video (if present) or the option ROM on a NuBus or PCI video card. Toolbox then checks for a disk in the floppy drive, and scans all SCSI buses for a disk with a valid System Folder, giving preference to whatever disk is set as the startup disk in the parameter RAM.
If a bootable disk is found, the Happy Mac logo is displayed, and control is handed over to the Mac OS. If no disk to boot from is present, an icon
Icon
An icon is a religious work of art, most commonly a painting, from Eastern Christianity and in certain Eastern Catholic churches...
depicting a floppy disk with a blinking question mark in the middle will be displayed. If a hardware problem occurs during the early part of the boot process, the machine will display the Sad Mac icon with a hexadecimal error code and freeze; and on Macs made after 1987, this will be accompanied by the Chimes of Death sound.
Since the Old World ROM usually boots to Toolbox, most OSes have to be installed using a boot loader from inside Mac OS (BootX
BootX (Linux)
BootX is the name of a graphical bootloader developed by Benjamin Herrenschmidt, which runs as an application or an extension to Mac OS 8 and 9 that allows Old World Apple computers to boot Linux. It is no longer maintained by its original author, as it does not work with any current hardware, but...
is commonly used for Linux installations). 68K-based Macs and NuBus Power Macs must have Mac OS installed to load another OS (even A/UX
A/UX
A/UX was Apple Computer’s implementation of the Unix operating system for some of their Macintosh computers. The later versions of A/UX ran on the Macintosh II, Quadra and Centris series of machines as well as the SE/30. A/UX was first released in 1988, with the final version released in 1995...
, which was an Apple product), usually with virtual memory
Virtual memory
In computing, virtual memory is a memory management technique developed for multitasking kernels. This technique virtualizes a computer architecture's various forms of computer data storage , allowing a program to be designed as though there is only one kind of memory, "virtual" memory, which...
turned off. PCI Power Macs can be configured to boot into Open Firmware, allowing the firmware to load a boot loader directly, or they can use a specially-prepared floppy disk to trick the Toolbox into loading a kernel (this is used for Linux
Linux
Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...
installation floppy images).
The simplest way to identify an Old World ROM Mac is that it will not have a factory built-in USB port. Only New World ROM Macs featured a USB port as factory equipment.
See also
- BootXBootX (Linux)BootX is the name of a graphical bootloader developed by Benjamin Herrenschmidt, which runs as an application or an extension to Mac OS 8 and 9 that allows Old World Apple computers to boot Linux. It is no longer maintained by its original author, as it does not work with any current hardware, but...
, the standard LinuxPPC boot loader for Old World machines - Quik (boot loader)Quik (boot loader)quik is a boot loader designed to start Linux on Apple Macintosh PowerPC systems based on the Old World ROM architecture. It was originally written by Paul Mackerras, and portions of its code were reused in all other Linux boot loaders for PowerPC, including the one known as BootX , which is...
, a replacement boot loader for Old World PCI systems