The Personal System/55 (パーソナルシステム/55) or PS/55 is a personal computer series released from IBM Japan in 1987. The PS/55 is the successor to IBM 5550 (Multistation 5550), but its architecture is based upon IBM PS/2, perhaps it is also an IBM clone. The first line-up of the series consisted of rebranded 5550 models except the Model 5570-S which was based on the PS/2 Model 80 (IBM 8580). Unlike the PS/2, most PS/2-based models have a 32-bit (80386 or 80486) CPU and Micro Channel (MCA) bus for the high-end business computing market. IBM Japan was hesitating to sell personal computers for consumers because the IBM JX failed. The AT bus model was released for home users in 1991.