DATAMATH CALCULATOR MUSEUM

MOSTEK Calculator Integrated Circuits

MOSTEK was founded in 1969 as a spin-off of Texas Instruments and engaged in the manufacturing and marketing of Metal Oxide Semiconductors and Large Scale Integration (MOS/LSI) integrated circuits. Already in May, 1970 MOSTEK started the development of the MK6010, the world's first "single-chip" calculator circuit for for Nippon Calculating Machine Company, better known under the brand Busicom. The MK6010 – introduced January, 1971 - was used in Busicom's first handheld model, the Handy LE-120. Sold in 1971, it was the world's smallest handheld calculator for at least a year.

Texas Instruments announced the "TMS1802 calculator-on-a-chip" in September 17, 1971, about a year later MOSTEK introduced the MK5020P, an improved calculator chip. Not only did MOSTEK attract the attention of the electronic community, but they also attracted the attention of major consumers of MOS circuits and the company began an important relationship with Hewlett-Packard as the major supplier of integrated circuits for H-P's scientific calculators. Hewlett-Packard soon became MOSTEK's largest customer. In addition, MOSTEK's memory production was on the way to making it the worlds leading RAM supplier.

Find a list of all known Texas Instruments calculator chips here.

The number system of MOSTEK gives immediately an idea if a calculator chip was a custom design (MK6***) or a commercial device (MK5***):

	MK1 - First product: A 256 bit shift register
	MK2 - ROM
	MK3 - Some ROM but mostly CPU like MK3870 F8 series
	MK4 - Memory
	MK5 - Telecom, industrial, calculator, clocks, DATACOM
	MK6 - Customized parts
	MK7 - CPU Cards

Thanks to Jim Garrett.

First "single chip" calulator

These chips are manufactured in a high-threshold, p-channel MOS process and using Dual-Inline-Ceramic cases with 40 pins.
The MK6010 did not have the clock generator or the display drivers. It operates from unusual voltages of -12V and -24V.

Type	Year	Function	Calculator	Comments
MK6010	1971	Basic	Busicom LE-120	First "single chip" calculator, outdates TMS1802
MK6018, MK6019	1972	Basic	Busicom Exec 121-DK	Memory, 12 digits
MK5010	1972	Basic	Rapidman 800	Identical device. Once design cleared customer hold time restriction then allowed to sell on open market

Early BASIC calculator chips

These chips are manufactured in an ion-implantation, depletion-mode load, P-channel MOS process and using Dual-Inline-Ceramic (DIP) or Plastic (N Package) cases with 28 pins.

Type	Year	Function	Calculator	Comments
MK5020A	1972	Basic	Heathkit IC-2006	[+=],[-=] keys, 8 digits
MK5020B	1972	Basic	Aristo M64	[+=],[-=] keys, 8 digits
MK5021	1972	Basic		[+=],[-=] keys, 10 digits

Later BASIC calculator chips

Enhanced chips with partly integrated display drivers and more functions.

Type	Year	Function	Calculator	Comments
MK6092P, MK5017	1973	Basic + Clock	Corvus 305	Sqr(x), 1/x, %, 10 digits Clock with date
MS5020A	1974	Basic	Corvus 310	Sqr(x), %, 8 digits
MK5020A	1974	Basic	Corvus 312	Sqr(x), %, 8 digits, different to MK5020A introduced in 1972!
MK5021B	1974	Basic	Corvus 300E	Sqr(x), 1/x, %, 10 digits
MS5021C	1973	Basic	Vanguard X·1010	Sqr(x), %, 10 digits
MK5022A	1974	Basic	Corvus 322	Memory, sqr(x), %, 8 digits
MK50203N	1974	Basic	Corvus 415, 307	Memory, 1/x, %, 8 digits
MK50280A	1974	Basic	Corvus 400 (early)	Counter, %, 8 digits
MK50281	1974	Basic		Memory, constant, %, 8 digits
MK50282A, N	1974	Basic	Corvus 400 (late)	Counter, constant, %, 8 digits
MK50283	1974	Basic		Memory, constant, sqr(x), %, 8 digits
MK50310N	1974	Basic	Corvus 411	Memory, sqr(x), 1/x, Pi, 8 digits
MK50311	1974	Basic		Memory, sqr(x), 1/x, x², 8 digits
MK50312A	1974	Basic	Corvus 615	Memory, sqr(x), 8 digits VFD-display
MK6225N	1975	Checkbook	Corvus 525 CheckMaster	Memory, 6 digits

Chip set for scientifical calculators

With the MK50075 MOSTEK created a novel architecture for scientific and financial calculators using external ROM circuits (read only memory).

Type	Year	Function	Calculator	Comments
MK50075	1975	Data processor	Corvus 500	Needs external ROM
MK50101	1975	Financial		ROM#1
MK50102	1975	Financial		ROM#2
MK50103	1975	Scientific	Corvus 500	ROM#1
MK50104	1975	Scientific	Corvus 500	ROM#2

Calculator chips manufactured for Hewlett-Packard

Custom specific designs.

Type	Year	Function	Calculator	Comments
HP65-CPU	1973	Programmable Scientific	HP-65	Hybride CPU-module
MK6111	1973	ROM	HP-65	ROM#1
MK6112	1973	ROM	HP-65	ROM#2
MK6113	1973	ROM	HP-65	ROM#3
MK6020	1972	Arithmetic Chip	HP-35, HP-45, HP-55, HP-70
MK6021	1972	Control and Timing Chip	HP-35
MK6022	1972	ROM 256*10 bits	HP-35	ROM#1
MK6023	1972	ROM 256*10 bits	HP-35	ROM#2
MK6024	1972	ROM 256*10 bits	HP-35	ROM#3
MK6036	1973	RAM 10*56 bits	HP-45, HP-55, HP-70
MK6134	1973	ROM 1024*10 bits	HP-55
MK6215	1974	Arithmetic Chip	HP-22, HP-25, HP-25C
MK6216	1974	Arithmetic Chip	HP-29C, HP95C, HP-97
MK6217	1974	Arithmetic Chip	HP-21
MK6220	1974	RAM 16*56 bits	HP-22, HP-25
MK6250	1975	Card Reader Control	HP-67, HP-97
MK60038	1975	ROM	HP-67	added Anode drivers
MK60126	1975	ROM	HP-25, HP-25C
MK60142	1975	ROM	HP-19C
MK60171	1975	ROM/RAM	HP-67, HP-97
MK60172	1975	ROM/RAM	HP-67, HP-97
MK60175	1975	ROM/RAM	HP-67
MK60176	1975	ROM/RAM	HP-67
MK60185	1975	ROM/RAM	HP-19C, HP-29C

Thanks to Eric Smith.

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