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ROM Read-Only Memory

Read-only memory (usually known by its acronym, ROM) is used in computers and other electronic devices to store programs and constant data. In mask ROM, the data is physically encoded in the circuit, so it can only be programmed during fabrication. While mask ROM are very economical in large quantities, there are some major disadvantages associated with the technology: The turnaround time between completing the data set for a mask ROM and receiving the finished product is long and bugs lead to a long cycle time.

Subsequent developments addressed these problems and the invention of EPROM, or Erasable Programmable Read-Only Memory, solved the problems, because the memory contend can be reset by exposure the silicon chip through a glass window in the housing to strong UV light. The same EPROM chip packaged into an opaque housing, results in the OTP-ROM, or One-time Programmable Read-Only Memory, a technology usually used for quick production ramp-up at higher costs. The development of the Flash Memory, a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory), allows changes in the programs or data on the fly and replaced mask ROM in most applications.

Texas Instruments used mask ROM both as program memory for calculators, for instance with the Solid State Software Modules of the TI-58/59 family and the program memory of the TI-81 graphing calculator, or as data memory of the Solid State Speech Modules of the Speak & Spell series. Other ROM intense applications are the Spell-Checker RR-1 and the Language Translator PS-5600.

In the 70s and early 80s Texas Instruments developed and manufactured their own mask ROM while in the heyday of the mask ROM between the early 80s till mid 90s Sharp Electronics Corp. of Japan dominated the market. Please find a list of Sharp mask ROM located in some TI products here. In most products the layout of the printed circuit board (PCB) was designed in a way to accommodate both mask ROM and OTP-ROM. This allowed a faster market introduction and gained some flexibility for bug fixing in the program. We know for the TI-82 graphing calculators at least 12 different ROM-Versions since its introduction in 1993. Please find a list of OTP-ROM used in TI products here. In 1998 Texas Instruments introduced with the TI-73 the first graphing calculator based on Flash technology and most subsequent designs are based on this design. Please find a brief overview about Flash-ROM used in TI calculators here.

Mask ROM

Manufacturer Type Capacity Access Time Power Supply Package Related Products
Sharp LH53259 32k*8 150 ns 5 Volt 28-pin SOP  
Sharp LH5359MY
1991
64k*8 150 ns 5 Volt 28-pin SOP TI-81 ROM-Version 1.8K
Sharp LH5359P6
1993
64k*8 150 ns 5 Volt 28-pin SOP TI-81 ROM-Version 2.0V
Sharp LH5359NN
1995
64k*8 150 ns 5 Volt 28-pin SOP TI-80 ROM-Version 4.0
Sharp LH53517 64k*8 150 ns 5 Volt 28-pin SOP  
Sharp LH53519 64k*8 150 ns 5 Volt 28-pin SOP  
Sharp LH531G7N
1993
128k*8 150 ns 5 Volt 28-pin SOP TI-82 ROM-Version 10.0  
Sharp LH531ARH
1993
128k*8 150 ns 5 Volt 28-pin SOP TI-82 ROM-Version 16.0  
Sharp LH531GN2
1992
128k*8 150 ns 5 Volt 28-pin SOP TI-85 ROM-Version x.x  
Sharp LH531GP0
1993
128k*8 150 ns 5 Volt 28-pin SOP TI-85 ROM-Version 9.0  
Sharp LH531GP4
1994
128k*8 150 ns 5 Volt 28-pin SOP TI-82 ROM-Version 18.0  
Sharp LH531GNK-82
1995
128k*8 150 ns 5 Volt 28-pin SOP TI-82 ROM-Version 19.0  
Sharp LH531GNM-85
1995
128k*8 150 ns 5 Volt 28-pin SOP TI-85 ROM-Version 10.0  
Sharp LH531V00 128k*8 100 ns 5 Volt 32-pin SOP  
Sharp LH530800 128k*8        
Sharp LH532000B 256k*8
128k*16
 150 ns 5 Volt 40-pin SOP  
Sharp LH532KZI TI883-01
1996
256k*8  150 ns 5 Volt 32-pin PLCC TI-83 ROM-Version 1.07000
Sharp LH532KZC TI883-03
1998
256k*8  150 ns 5 Volt 32-pin PLCC TI-83 VSC ROM-Version 1.10
Sharp LH532KZ9
T886L-01
1998
256k*8  150 ns 5 Volt 32-pin PLCC TI-86 (1998)
Sharp LH532100B 256k*8  150 ns 5 Volt 32-pin SOP  
Sharp LH534A00 512k*8  120 ns 5 Volt 32-pin SOP  
Sharp LH534B00 512k*8  120 ns 5 Volt 40-pin SOP  
Sharp LH534700 512k*8        
Sharp LH538 1024k*8        
Sharp LH5388 1024k*8   5 Volt 44-pin SOP TI-92
Sharp LH537T08 2048k*8        
Sharp LH5316P00B 2048k*8
1024k*16
 120 ns 5 Volt 44-pin SOP  
Sharp LH536 3072k*8        
Sharp LH535 4096k*8        
Macronix MX J9533
1995
128k*8     28-pin SOP TI-82 ROM-Version 19.0  
Macronix MX TA1782
2000
128k*8     32-pin PLCC TI-82 ROM-Version 19.006
Macronix MX ??? 128k*8     32-pin PLCC TI-82 STATS ROM-Version 1.10001
Macronix MX TI83-02
1996
256k*8     32-pin PLCC TI-83 ROM-Version 1.07000
Macronix MX TI883-03
1998
256k*8     32-pin PLCC TI-83 ROM-Version 1.08000
Macronix MX ??? 256k*8     32-pin PLCC TI-83 Parcus ROM-Version 1.10001
IEC IEC9895S-
960819E
1024k*8 5 Volt 44-pin SOP TI-92 E Module
IEC IEC9895S
960411N
1024k*8 5 Volt 44-pin SOP TI-92 ROM-Version 1.11
IEC IEC10503
-03
(256k*8)     PS-5400
IEC IEC50387
-01, 02
(256k*8)       PS-5800
Hitachi HN61256 32k*8 4 us 5 Volt   CC 40, TI-74, TI-95
NEC uPD23C1024 64k*16 100 ns 5 Volt   PS-3000

OTP-ROM

Manufacturer Type Capacity Access Time Power Supply Package Related Products
AB AB23512 0055 64k*8 150 ns 5 Volt 28-pin SOP PS-6560i, PS-6760i, PS-6860i
AB AB23512 0063 64k*8 150 ns 5 Volt 28-pin SOP PM 200, PM 300, PM 400
Atmel AT27C512 64k*8 150 ns 5 Volt 28-pin SOP PS-6700
Atmel AT27C040 512k*8 70 ns 5 Volt 32-pin TSOP TI-92 (1996)
Macronix MX27C512 64k*8 150 ns 5 Volt 28-pin SOP PS-6700, PS-6860Si
Toshiba TC531000 128k*8    5 Volt 28-pin SOP RR-1
Toshiba TC534000 512k*8    5 Volt 32-pin SOP RR-2, PS-4000
Toshiba TC541001A 128k*8 120 ns 5 Volt 32-pin SOP TI-82 ES, TI-85 (1992)

Flash-ROM (NOR Technology)

Manufacturer Type Capacity Access Time Power Supply Package Related Products
Atmel AT29C020 256k*8 70 ns 5 Volt 32-pin PLCC TI-86 (1997)
AMD
Fujitsu
Macronix
29F400
29F400
MX29F400
512k*8
256k*16
70 ns 5 Volt 48-pin TSOP TI-73, TI-73 Explorer, TI-83 Plus
Fujitsu  
Spansion
Macronix
EON Silicon Sol.
29LV400
S29AL004D
MX29LV400
EN29LV400
 512k*8
256k*16
70 ns 3 Volt 48-pin TSOP PLT FHH1, PLT SHH1, PLT SU1, PLT VIEW, TI-82 Stats.fr, TI-73 Explorer, TI-76.fr, TI-82 STATS
Macronix MX29SL402  512k*8
256k*16
90 ns 1.8 Volt 48-pin TSOP TI-Nspire COLOR
AMD
Fujitsu 
29F800
29F800
1024k*8
512k*16
55 ns 5 Volt 48-pin TSOP CBL2
AMIC
Fujitsu  
Spansion
Macronix
A29L800A
29LV800
S29AL008D
MX29LV800
 1024k*8
512k*16
70 ns 3 Volt 48-pin TSOP TI-84 Plus, TI-84 PLUS.fr, TI-83 Plus.fr (DVT)
Fujitsu  
Spansion
Macronix
EON
29LV160
S29AL016D
MX29LV160
 2048k*8
1024k*16
70 ns 3 Volt 48-pin TSOP TI-83 Plus S.E., TI-84 Plus S.E.,
TI-83 Plus.fr (2013)
Macronix MX29LV320  4096k*8
2048k*16
70 ns 3 Volt 48-pin TSOP TI-84 Plus C S.E.
Sharp LH28F016SA 2048k*8
1024k*16
120 ns 3 Volt 56-pin TSOP TI-92 II, TI-92 II Module, TI-92 Plus Module
Sharp LH28F016SC 2048k*8  120 ns  3 Volt 40-pin TSOP  
Sharp LH28F160S3T 2048k*8
1024k*16
 100 ns  3 Volt 56-pin TSOP TI-89, TI-92 Plus
Sharp LH28F320 2048k*16  100 ns  3 Volt 48-pin TSOP TI-89 Titanium, Voyage 200, TI-89 T Presentation Link Adapter
SST  39VF400A 256k*16 70 ns 3.3 Volt 48-ball FBGA TI-Nspire CAS+
SST 39WF400A 256k*16 90 ns 1.8 Volt 48-ball FBGA TI-Nspire, TI-Nspire CAS

Spansion was founded in 1993 as a joint venture between AMD and Japan's Fujitsu Limited. AMD took control of the company in 2003 and spun it off as an independent maker of Flash-ROM chips in December 2005.

EON (Eon Silicon Solution, Inc.) is a fabless semiconductor company based in Hsin-Chu, Taiwan and focusing on non-volatile memory.

Flash-ROM (NAND Technology)

Manufacturer Type Capacity Access Time Power Supply Package Related Products
Samsung K9F5608R0D 32M*8 10 us 1.8 Volt 63-ball FBGA TI-Nspire 2, TI-Nsprie CAS 2
ST NAND256
R3A
32M*8
16M*16
15 us 1.8 Volt 48-pin TSOP
55-ball FBGA
TI-Nspire, TI-Nspire CAS
ST NAND256
W3A
32M*8
16M*16
12 us 3.3 Volt 48-pin TSOP
55-ball FBGA
TI-Nspire CAS+
Toshiba  TC58V64A 8M*8 25 us 3 Volt 48-pin TSOP PLT SHH1
Toshiba  TC58128A 16M*8 25 us 3 Volt 48-pin TSOP PLT FHH1, PLT VIEW
Toshiba  TC58DVM82A 32M*8 25 us 3 Volt 48-pin TSOP PLT SU1

 

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If you have additions to the above article please email: joerg@datamath.org.

Joerg Woerner, February 12, 2009. No reprints without written permission.