I have the main unit and power adapter.
type computer
country USA
year 1991
os IBM OS/2 / Windows 3.1
cpu Intel 80386SX
speed 20 MHz
ram 2 MB
disk 3.5″ 1.44 KB
hd 60 MB
graphic Monochrome 640 x 480 LCD
colors 32 shades of gray
sound beeper
ports monitor, mouse, printer
The IBM PS/2 L40SX — IBM’s Best Laptop Keyboard
Released on 26 March 1991, the IBM PS/2 L40SX was IBM’s first genuinely competitive laptop computer — a 386SX-based machine that finally gave IBM a credible portable offering after the limited success of the PC Convertible. Developed in just thirteen months (remarkably fast for IBM), the L40SX used a 20 MHz Intel 386SX processor, sidelit monochrome LCD display, and up to 18 MB of RAM. But its most celebrated feature was its keyboard — an unusually large, full-travel keyboard that many users considered the finest laptop keyboard ever made, deliberately designed to avoid repeating the mistake of the PCjr’s despised chiclet keys.
The PCjr Lesson
IBM’s decision to give the L40SX a large, full-travel keyboard was directly informed by the catastrophic failure of the IBM PCjr in 1983 — a machine whose tiny, flat ”chiclet” keyboard had been widely ridiculed and was a major factor in its commercial failure. IBM engineers were determined that no future IBM machine would repeat that mistake. The L40SX’s keyboard was so well-regarded that IBM later sold a standalone version with a built-in TrackPoint as the IBM Model M4-1 — one of the few laptop keyboards ever deemed worthy of standalone sale.
Electroless Plating Innovation
The L40SX’s development involved a novel manufacturing technique: electroless plating of the polycarbonate-ABS case to provide electromagnetic interference shielding. Most manufacturers of the era used metallic paint spray for EMI shielding, but the 386SX’s electromagnetic emissions overrode this approach. IBM commissioned novel research with Dow Chemical to develop electroless plating suitable for laptop cases — an expensive but technically superior solution that reflected IBM’s willingness to invest in engineering quality.
Predecessor to ThinkPad
The L40SX was the final IBM laptop before the revolutionary ThinkPad 700C arrived in October 1992. The engineering lessons learned from the L40SX’s development directly informed the ThinkPad programme, making the L40SX an important stepping stone toward one of the most successful and beloved laptop lines in computing history.