Texas Instruments Constant Memory Module (DVT)

Date of introduction:  Never
 (Announced: May 1982)
Display technology:  
New price:  MSRP: $50.00 Display size:  
Size:  1.3" x 1.25" x 0.55"
 33 x 32 x 14 mm3
Weight:  0.45 ounces, 13 grams Serial No:  
Batteries:  LF-1/2W Date of manufacture:  wk 39 year 1981
AC-Adapter:   Origin of manufacture:  USA (ATA)
Precision:  0-1184 Integrated circuits:  2 x TP531
Memories:  148-0    
Program steps:   Courtesy of:  Joerg Woerner

The Constant Memory Module was developed by Texas Instruments for its TI-88 Programmable calculator system and available as an option the calculator.

This Constant Memory Module was included with an early TI-88 DVT (Design Validation Test) and sports a label missing the 'Constant' indicating the included backup battery.

Dismantling a Constant Memory Module included with a later TI-88 PVT (Production Validation Test) and manufactured in September 1982 by Texas Instruments in their Abilene, Texas facility, reveals a printed circuit board (PCB) to accommodate up to two TP530 Memory Chips. The PCB is populated with two TP531 Read/Write Memories (RAM) with unknown capacity and a Sanyo 3 Volts lithium battery from the type LF-1/2W with 24.0 mm diameter and a thickness of 3.0 mm - matching today's CR2430 cells.



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Joerg Woerner, October 12, 2019. No reprints without written permission.