New World ROM
Encyclopedia
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 (typically from to ), and facilitated the use of Flash memory
for system firmware instead of the now more expensive and less flexible Mask ROM
that most previous Macs used. A facility for loading the Toolbox from the startup device was, however, made available, allowing the use of Mac OS 8
and Mac OS 9
on New World machines.
The New World architecture was developed for the Macintosh Network Computer, an unrealized project that eventually contributed several key technologies to the first-generation iMac.
All PowerPC
Macs from the iMac
forward are New World ROM machines, while all previous models (including all beige and platinum Macs) are Old World ROM
machines. Intel based Macs are incapable of running Mac OS 9, and on these machines EFI is used instead of Open Firmware
, which both New World and Old World machines are based on.
New World ROM Macs are the first Macs where direct usage of the Open Firmware
(OF) subsystem is encouraged. Previous PCI
Power Macs
used Open Firmware for booting, but the implementation was not complete; in these machines OF was only expected to probe PCI devices, then immediately hand control over to the Mac OS ROM. Because of this, versions 1.0.5 and 2.x had several serious bugs, as well as missing functionality (such as being able to load files from a HFS
partition or a TFTP
server). Apple also set the default input and output devices to ttya (the modem port on beige Macs), which made it difficult for normal users to get to Open Firmware; to do so it was necessary to either hook up a terminal, or change the Open Firmware settings from inside Mac OS using a tool such as Boot Variables or Apple's System Disk.
The New World ROM introduced a much-improved version of the Open Firmware interpreter, version 3.0, which added many missing features, fixed most of the bugs from earlier versions, and had the capability to run CHRP
boot scripts. The Toolbox ROM was embedded inside a CHRP script in the System Folder called "Mac OS ROM", along with a short loader stub and a copy of the Happy Mac icon suitable for display from Open Firmware. Once the ROM was loaded from disk, the Mac boot sequence continued as usual. As before, Open Firmware could also run a binary boot loader, and version 3.0 added support for ELF
objects as well as the XCOFF
files versions 1.0.5 and 2.0 supported. Also, version 3.0 (as well as some of the last releases of version 2.x, starting with the PowerBook
3400) officially supported direct access to the Open Firmware command prompt from the console (by setting the auto-boot? variable to false from Mac OS, or by holding down Command-Option-O-F at boot).
One major difference between Old World ROM Macs and New World ROM Macs, at least in classic Mac OS, is that the Gestalt
selector for the machine type is no longer usable; all New World ROM Macs use the same mach ID, 406 decimal, and the actual machine ID is encoded in the "model" and "compatible" properties of the root node of the Open Firmware device tree. The New World ROM also sets the "compatible" property of the root node to "MacRISC2" (machines that can boot classic Mac OS using "Mac OS ROM") or "MacRISC3" (machines that can only boot Mac OS X
or another Unix
-like system).
It is somewhat easier to boot a non-Mac-OS operating system on a New World system, and indeed OpenBSD
's bootloader only works on a New World system.
The simplest way to distinguish a New World ROM Mac is that it will have a factory built-in USB port. No Old World ROM Mac had a USB port as factory equipment; instead, they used ADB
for keyboard and mouse, and mini-DIN-8 "modem" and "printer" serial ports for other peripherals. Also, NewWorld ROM Macs generally do not have a built-in floppy drive.
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...
on the logic board. Due to Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
not requiring the availability of the Toolbox, this allowed ROM sizes to shrink dramatically (typically from to ), and facilitated the use of Flash memory
Flash memory
Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from EEPROM and must be erased in fairly large blocks before these can be rewritten with new data...
for system firmware instead of the now more expensive and less flexible Mask ROM
Mask ROM
Mask ROM is a type of read-only memory whose contents are programmed by the integrated circuit manufacturer...
that most previous Macs used. A facility for loading the Toolbox from the startup device was, however, made available, allowing the use of Mac OS 8
Mac OS 8
Mac OS 8 is an operating system that was released by Apple Computer on July 26, 1997. It represented the largest overhaul of the Mac OS since the release of System 7, some six years previously. It puts more emphasis on color than previous operating systems...
and Mac OS 9
Mac OS 9
Mac OS 9 is the final major release of Apple's Mac OS before the launch of Mac OS X. Introduced on October 23, 1999, Apple positioned it as "The Best Internet Operating System Ever," highlighting Sherlock 2's Internet search capabilities, integration with Apple's free online services known as...
on New World machines.
The New World architecture was developed for the Macintosh Network Computer, an unrealized project that eventually contributed several key technologies to the first-generation iMac.
All PowerPC
PowerPC
PowerPC is a RISC architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM...
Macs from 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....
forward are New World ROM machines, while all previous models (including all beige and platinum Macs) are Old World ROM
Old World ROM
Old World ROM Macintosh computers are the Macintosh models that use a Macintosh Toolbox ROM chip, usually in a socket . All Macs prior to the iMac use Old World ROM, while the iMac and all subsequent models until the introduction of the Intel-based EFI Models are New World ROM machines...
machines. Intel based Macs are incapable of running Mac OS 9, and on these machines EFI is used instead of 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...
, which both New World and Old World machines are based on.
New World ROM Macs are the first Macs where direct usage of the 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...
(OF) subsystem is encouraged. Previous PCI
Peripheral Component Interconnect
Conventional PCI is a computer bus for attaching hardware devices in a computer...
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,...
used Open Firmware for booting, but the implementation was not complete; in these machines OF was only expected to probe PCI devices, then immediately hand control over to the Mac OS ROM. Because of this, versions 1.0.5 and 2.x had several serious bugs, as well as missing functionality (such as being able to load files from a HFS
Hierarchical File System
Hierarchical File System is a file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs...
partition or a TFTP
Trivial File Transfer Protocol
Trivial File Transfer Protocol is a file transfer protocol known for its simplicity. It is generally used forautomated transfer of configuration or boot files between machines in a local environment....
server). Apple also set the default input and output devices to ttya (the modem port on beige Macs), which made it difficult for normal users to get to Open Firmware; to do so it was necessary to either hook up a terminal, or change the Open Firmware settings from inside Mac OS using a tool such as Boot Variables or Apple's System Disk.
The New World ROM introduced a much-improved version of the Open Firmware interpreter, version 3.0, which added many missing features, fixed most of the bugs from earlier versions, and had the capability to run CHRP
Common Hardware Reference Platform
Common Hardware Reference Platform was a standard system architecture for PowerPC based computer systems published jointly by IBM and Apple in 1995. Like its predecessor PReP, it was conceptualized as a design to allow various operating systems to run on an industry standard hardware platform,...
boot scripts. The Toolbox ROM was embedded inside a CHRP script in the System Folder called "Mac OS ROM", along with a short loader stub and a copy of the Happy Mac icon suitable for display from Open Firmware. Once the ROM was loaded from disk, the Mac boot sequence continued as usual. As before, Open Firmware could also run a binary boot loader, and version 3.0 added support for ELF
Executable and Linkable Format
In computing, the Executable and Linkable Format is a common standard file format for executables, object code, shared libraries, and core dumps. First published in the System V Application Binary Interface specification, and later in the Tool Interface Standard, it was quickly accepted among...
objects as well as the XCOFF
XCOFF
XCOFF, for "eXtended COFF", is an improved and expanded version of the COFF object file format defined by IBM and used in AIX. Early versions of the PowerPC Macintosh also supported XCOFF, as did BeOS....
files versions 1.0.5 and 2.0 supported. Also, version 3.0 (as well as some of the last releases of version 2.x, starting with the PowerBook
PowerBook
The PowerBook was a line of Macintosh laptop computers that was designed, manufactured and sold by Apple Computer, Inc. from 1991 to 2006. During its lifetime, the PowerBook went through several major revisions and redesigns, often being the first to incorporate features that would later become...
3400) officially supported direct access to the Open Firmware command prompt from the console (by setting the auto-boot? variable to false from Mac OS, or by holding down Command-Option-O-F at boot).
One major difference between Old World ROM Macs and New World ROM Macs, at least in classic Mac OS, is that the Gestalt
Gestalt (Mac OS)
Gestalt was the name of a system call introduced into the Apple Macintosh operating system System Software 6.0.4 in 1989 to allow applications to dynamically query what capabilities were present in the running system configuration....
selector for the machine type is no longer usable; all New World ROM Macs use the same mach ID, 406 decimal, and the actual machine ID is encoded in the "model" and "compatible" properties of the root node of the Open Firmware device tree. The New World ROM also sets the "compatible" property of the root node to "MacRISC2" (machines that can boot classic Mac OS using "Mac OS ROM") or "MacRISC3" (machines that can only boot Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
or another Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
-like system).
It is somewhat easier to boot a non-Mac-OS operating system on a New World system, and indeed OpenBSD
OpenBSD
OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution , a Unix derivative developed at the University of California, Berkeley. It was forked from NetBSD by project leader Theo de Raadt in late 1995...
's bootloader only works on a New World system.
The simplest way to distinguish a New World ROM Mac is that it will have a factory built-in USB port. No Old World ROM Mac had a USB port as factory equipment; instead, they used ADB
Apple Desktop Bus
Apple Desktop Bus is an obsolete bit-serial computer bus connecting low-speed devices to computers. Used primarily on the Macintosh platform, ADB equipment is still available but not supported by most Apple hardware manufactured since 1999....
for keyboard and mouse, and mini-DIN-8 "modem" and "printer" serial ports for other peripherals. Also, NewWorld ROM Macs generally do not have a built-in floppy drive.
External links
- The Mac ROM Enters a New World Apple's original New World ROM documentation