Accelerator card
Turbo cards are expansion boards for Commodore - Amiga computers that have their own CPU and replace the original CPU of the computer. With the exception of the Amiga 4000 , which did not have a CPU on the main board, but instead used a replaceable CPU sub-board from the start, the original CPU i remains. a. Usually unused (deactivated) in the computer. In the Amiga 500 , the CPU was removed from the module base and replaced by a suitable circuit board.
The Amiga is considerably accelerated by using a turbo card . There are several reasons for this:
- The accelerator card contains a significantly more powerful CPU than the original CPU (e.g. 68020 versus 68000 )
- The CPU of the accelerator card is clocked higher (e.g. 68030 with 50 MHz compared to 68020 with 14 MHz)
- The accelerator card is usually equipped with its own FastRAM , which is connected to the CPU via its own 32-bit bus and runs at the clock rate of the CPU.
- Often a base for a math coprocessor ( 68881 or 68882 ) is provided, which only accelerates special software.
In addition, accelerator cards often contain fast peripherals with high data throughput that are directly coupled to the 32-bit bus of the CPU, such as B. SCSI controller or later a GPU .
After the development of the Amiga came to a standstill in the 1990s, further development by external companies (such as Phase5 ) was focused on the basis of accelerator cards, because it was possible to build on these own architectures that could avoid the disadvantages of the original Amiga hardware.
All accelerator cards used a Motorola MC68000 series processor (68020, 68030, 68040 or 68060 ) on which the code could run natively. At the end of the 1990s, Phase5 also offered turbo cards with PowerPC CPUs 603e and 604. These had a 68040 or 68060 as the main processor on which the native Amiga code ran, and also a PowerPC as a coprocessor , which executed PPC's own code.
The Metabox company planned and developed from 1999 on the basis of their "JoeCard" series for the Apple Macintosh processor cards for the Amiga ("AmiJoe"), which exclusively use a fast PowerPC CPU ( PPC 750 ) with a clock frequency of 333 MHz ( Amiga 1200) or 400 MHz (Amiga 2000/3000/4000) should have. With this card the Amiga code should be executed by means of emulation in the Flash-ROM , nevertheless with a mature 68k emulation a fifty to eighty percent higher performance (compared to a 68060 processor clocked with 50 MHz) would have been possible. The plans changed several times, finally Metabox concentrated exclusively on the card for the Amiga 1200. Due to the bankruptcy of the company in 2001, however, it did not get beyond the prototype stage .
Since the AmigaOS did not contain any PPC code, the PPC could only take on selective tasks. In the medium term, the Amiga OS (similar to the Apple Macintosh) should be completely converted from the 68000 to the PowerPC basis, but this was only implemented years later by the Hyperion Entertainment company due to the slow development of the AmigaOS.
Modern accelerator cards, which are developed and manufactured for the classic Amiga computers, take into account the architecture of the old systems in a special way and offer solutions to problems that could not always be solved with contemporary cards. For example, modern accelerator cards are able to prevent the PCMCIA port from being switched off on Amiga 600 or Amiga 1200 computers, despite the large amount of memory available, which often occurred with older cards with large memory.
Individual evidence
- ↑ JoeCard goes Amiga, message from March 27, 1999 on amiga-news.de, accessed on March 2, 2015
- ↑ All good things are (G) 3 in: amigaOS - The specialist magazine for Amiga users, issue 05/1999, page 29