Model 60 The PS/2 Model 60 was introduced on April 2, 1987, alongside the lower-end
Model 30 and the midrange
Model 50. Both the PS/2 Model 60 and the Model 50 featured identical
Intel 80286 processors clocked at 10 MHz and served as the public market introduction of
Video Graphics Array (VGA) and
Micro Channel architecture (MCA). MCA was a proprietary
bus standard designed by IBM to replace the aging
Industry Standard Architecture (ISA) first used in their earlier
IBM PCs, while VGA was an upgraded graphics standard for IBM's PCs and compatibles, supporting higher resolutions and greater color bit depth. Unlike the Model 50, the Model 60 built into a
tower computer case and featured four additional 16-bit
MCA expansion slots as well as an additional
drive bay. Because of the Model 60's increased potential for connectivity and multitasking, technology journalists envisioned the PS/2 Model 60 as a multiuser machine. The Model 60 was originally available in two configurations: one with a 44-MB,
ST-506 hard disk drive, for US$5,295; and another with a 70-MB hard drive and a faster
ESDI disk interface, for $6,295. This compared to $3,595 for the midrange Model 50. Owing to its relatively slow
DRAM, rated for 125-ns access times, the original Model 60 inserts
wait states for every memory access operation, leading to compromised performance compared to 286-class machines with an equivalent clock speed but faster RAM. This same issue also plagued the original Personal System/2 Model 50, which IBM corrected with the
Model 50 Z in 1988. The Model 60 continued to have the same slow RAM chips throughout its existence, however.
Model 65 SX On March 20, 1990, IBM introduced the PS/2 Model 65 SX, featuring the cost-reduced
i386SX processor by Intel clocked at 16 MHz. Internally, the i386SX supports 32-bit operations, but its data bus could only access RAM 16 bits at a time. Because of this, the Model 65 SX contains only 16-bit MCA slots, exactly like the Model 60. The Model 65 SX upgraded the on-board disk controller to
SCSI from ESDI and had faster on-board memory chips and support for 1 MB more of RAM, however. The Model 65 SX directly replaced the Model 60, the final units of which rolled off the line at
IBM's factory in Boca Raton in October 1990. ==Sales and reception==