CPU: Intel 8088@4.77Mhz (8bit version of 8086 and is fully compatible)
RAM: 256K (Expandable to 512K + 80K Dual Bus Memory)
Display: Unknown (Probs monochrome and/or CGA)
Floppy: 360K 5.25" Drive
Bus: 3 x 8bit ISA Slots
Unlike most other bridgeboards, the sidecar is literally an entire PC in a box. It was specifically designed to fit to the 86pin side expansion of the A1000. It is probably electrically compatible with the A500, however the physical dimensions will cause problems due to the A500 expansion slot being on the opposite side. The sidecar has a 5.25inch expansion bay for fitting a floppy drive and an internal power supply. It also has an expansion pass-through.
Thanks to Erik Inge Bolsų and Hrothgar.