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Features

The MK502X is a programmable single-chip calculator which is both pin compatible and function compatible with the Texas Instruments one-chip calculator circuit TMS0102. Improved features are available from the MK502X, including:

	Lower power dissipation
	Single supply operation
	Broader supply voltage operating range
	Internal clock oscillator
	More extensive programmability

The first four functions above were made possible through the use of MOSTEK's ion-implantation, depletion-mode load, P-channel MOS process. These features make the MK502X ideal for battery operated hand-held calculators where battery life and calculator compactness are prime considerations. The more extensive programmability of the MK502X allows implementation of complex special functions through custom programming. 

Due to a flexible design concept with both programmable PLA and ROM techniques a lot of design variations appeared. These include different types of the key-matrix, 8 or 10 digits of 7- or 8-segmented outputs. The two letters behind the product designation define the ROM-code (A,B,C...) and package (P for ceramic housing).

A typical calculator built around the MK502X family performs the four basic functions +,-,*,: with either Constant or Chain operation. The calculations are done on a floating decimal-point operation but the display of the results could be selected between the floating-point or a fixed-point format. The keyboard scanning, debouncing and encoding in performed inside the chip. The display outputs are fully decoded with a leading zero suppresion and multiplexed.

Family Members and Usage

Type	Calculator	Digits
MK5020A	Heathkit IC-2006	8
MK5020B	Aristo M64	8
MK5021A		10

 

Technical Specification

Item	Min	Typ	Max	Unit	Comments
VSS		0		V
VGG	-11.0	-14.4	-17.0	V
IGG		6.5		mA
CK		182		kHz	200kOhm and 36pF

	Housing The MK502X P uses a standard DIL-28 ceramic package.
	Pin Description

Pin	IO	Function	Pin	IO	Function
1	I	Clock Input	28	V	Common Voltage
2	I	Keymatrix input P	27	I	Keymatrix input Q
3	O	Digit driver 1 (LSD)	26	I	Keymatrix input N
4	O	Digit driver 2	25	I	Keymatrix input O
5	O	Digit driver 3	24	O	Segment driver DP
6	O	Digit driver 4	23	O	Segment driver H
7	O	Digit driver 5	22	O	Segment driver G
8	O	Digit driver 6	21	O	Segment driver F
9	O	Digit driver 7	20	O	Segment driver E
10	O	Digit driver 8 (MSD8)	19	O	Segment driver D
11	O	Digit driver 9	18	O	Segment driver C
12	O	Digit driver 10 (MSD10)	17	O	Segment driver B
13	O	Digit driver 11 (OVER)	16	O	Segment driver A
14	T	Test input	15	V	Negative Voltage VGG

The Segment drivers A-H and the Decimal point are connected to a display in the pictured way.

Keyboard Scanmatrix

The keyboards of all calculators based on the MK502X family consist of a x/y-matrix connected to the  digit driver outputs D1-D11 and the keymatrix inputs KN and KO. In the fixed-point output format mode the position of the decimal point is selcted with the KP input. The Constant/Chain switch is connected between D10-KQ.

	MK5020					MK5021
	KN	KO	KP	KQ		KN	KO	KP	KQ
D1	1	+	DP1		D1	1	+	DP1
D2	2	*	DP2		D2	2	*	DP2
D3	3	:	DP3		D3	3	:	DP3
D4	4	-	DP4		D4	4	-	DP4
D5	5	+=	DP5		D5	5	+=	DP5
D6	6	-=	DP6		D6	6	-=	DP6
D7	7	+/-	DP7	RND up	D7	7	+/-	DP7	RND up
D8	8	=			D8	8	=	DP8
D9	9	.		RND dwn	D9	9	.	DP9	RND dwn
D10	0	CE	DP0	K	D10	0	CE	DP0	K
D11	%	C			D11	%	C

Display