Amiga Sidecar

The Sidecar-expansion for the A1000 is in essence a complete IBM Personal Computer XT-clone in itself with its own motherboard, yet in an expansion case, which connects to the expansion-bus on the right side of the Amiga 1000 computer (→ Side-expansion Port). Is built around the same Intel 8088 processor, the original IBM PC/XT (→ IBM 5160) was already build around, although Commodore shipped it mostly using German Siemens CPUs or other CPU-variants from Asian vendors (likely due to lower costs).^{[Note 1]}

Amiga-Software as well as PC-programs were included to allow data to be exchanged easily between the PC- and the Amiga-side of the system, as well as copying displayed screen-content of the PC-side. Among esle, it enabled even to simply copy the screen-content of the integrated PC-side per the Amiga-mouse (by simple selection), to be directly pasted into the Amiga's clipboard via the typical way of Copy'nPaste we know today, which was still revolutionary for the time of the Sidecar.

The Sidecar had an internal hard disk, which was accessible from both the DOS and AmigaOS environments at the same time, to be partitioned as PC- and Amiga harddisk simultaniously, where it was possible to partition one for the PC and others for the Amiga itself. Although the Amiga A1000 was not meant to boot from the harddisk, the PC actually indeed was. This was also the first hard-drive ever produced by Commodore for the Amiga itself.

The video display and user input are performed through the Amiga's monitor, keyboard, and mouse. This allows the user to control both computers simultaneously through the Amiga only.

All I/O from the PC side is performed by and through the Amiga itself, as the Sidecare itself has no I/O-ports other than the internal ISA-slots for IBM-compatible expansion-cards.

The Sidecar was developed by Commodore Germany, as was all of the Commodore PC-architecture based development. It was relatively expensive and it required a non-trivial amount of desktop space compared to the Amiga 1000 by itself. The device was also taller than the Amiga 1000, which made it seem even more aesthetically disconnected from the main system.

The Sidecar could also not be used with a stock A1000, as it had to have at least 512 KB of Chip-RAM for working with the Sidecar in the first place.
Thus the A1000 neededs to first have the A1050-expansion installed beforehand, increasing the already high acquisition costs for the whole system even further.^{[Note 2]}

Besides the high price and the aesthetic issues, other factors contributed to the Sidecar's lack of adoption. The Amiga 2000 provided internal expansion slots, allowing the optional Bridgeboard card to replace the functionality of the Sidecar without needing a bulky external chassis. The popular Amiga 500 could not be used with the Sidecar at all, due to the expansion slot on the A500 residing on the left side of the chassis, as opposed to the right side on the A1000. Also, decent business and productivity software began to be released for AmigaOS, reducing the need to run MS-DOS applications on the Amiga.

The Sidecar's conpect of compatibility through hardware-expansions was continued in the later Amiga 2000 unit, containing four ISA slots intended for PC emulation expandability. Two slots were in-line with the Amiga Zorro II bus to allow installation of a Bridgeboard which, like the Sidecar, provided the core chipset of a PC on an expansion card, connected to both the Amiga and PC bus.

Early in its life, the Amiga was strong in entertainment and graphics software but lacked general productivity software such as word processors, spreadsheets and database software. These are the areas where the de facto business standard IBM PC excelled. Commodore's intent was to let the Amiga take advantage of PC compatibility to shore up its weakness in this category of software.

Bruce F. Webster wrote in the October 1985 issue of BYTE, after seeing the Amiga for the first time:^[3]

The 86-pin [expansion port] gives whatever is sitting out there complete control of the machine (if it wants control). The disk-controller hardware can already handle 5¼-inch drives ... the keyboard is sufficiently populated [to] support most MS-DOS programs, and the screen resolutions (320 by 200, etc.) are, by an amazing coincidence, identical to those for most IBM graphics cards. How hard would it be to build a box with the necessary CPU and ROMs that would turn the Amiga into an IBM-compatible machine? Not very hard, I would think—certainly not as hard as it has been for the folks at Dayna Communications to get MacCharlie, which attempts to get the Mac run MS-DOS software, up and running.

Webster, in September 1986, noted the Sidecar's announcement as fulfilling his prediction.^[4] Jerry Pournelle that month named the Sidecar his "number one pick of Spring COMDEX, stating that "it was eerie to watch Flight Simulator running as if on a PC and still see the famous Amiga bouncing ball in the background and a word-processing program running in the foreground".^[5]

The Amiga Sidecar is a complete IBM PC XT system, with the exception of I/O devices and operations (which are handled by the Amiga).

• Processor: Intel 8088 @ 4.77 MHz
• RAM: 256 kB (expandable to 512 kB + 80 kB Dual Bus Memory)
• Graphics Emulation: Dependent on Amiga settings. (can use 8-bit ISA graphics cards)
• Sound Emulation: Dependent on Amiga settings. (can use real 8-bit ISA sound cards)
• One internal 5.25" drive bay (normally fitted with a 360K 5.25" floppy drive)
• 3 x 8-bit ISA slots (for using PC expansion cards)
• Amiga 1000 Expansion Bus connector (for Amiga connectivity)
• Additional slot for an 8087 numeric coprocessor^[6]

• MacCharlie