The 5900B was designed for BASIC programmers, as each key had a BASIC command as an alternative value. The unit looked similar to an Hewlett-Packard HP-85.
One of the 9500’s 8088 processors handled I/O chores while the other was dedicated to communications tasks.
Seiko 5900B (desktop)
Base Configuration: 8085A CPU; Seiko bus; 128K RAM; 2K ROM; 5.25-inch floppy disk drive; integral monochrome CRT, keyboard/keypad, and printer; RS-232C, GP-IB, and BCD ports; Seiko BASIC
Size/Weight: 18.7 x 7.3 x 23 inches, 42.5 lbs.
Seiko 7500 (desktop)
Base Configuration: 8085A CPU, Seiko bus, 64K RAM, 72K ROM, 5.25-inch floppy disk drive, integral monochrome CRT and keyboard/keypad, GP-IB and BCD ports, Seiko BASIC
Size/Weight: 20.3 x 14.6 x 21.45 inches, 55.9 lbs.
Seiko 9500 (1983, desktop)
Base Configuration: 8086 and two 8088 CPUs, RMX/86, 256K RAM (512K max)
Video: 512 x 480 graphics