Actual pictures. Vintage used slot machine mainboard based on z80 cpu and y8910 sound chip. 

There are different firmwares (Fruitcocktail, Garage, Belyash, Resident). One firmware on one board. Fully tested, work fine. 

Source of the manual, schemas - igrotechnics.ru/igrovye-avtomaty/igrovye-avtomaty-igrosoft.ht  m l

COMPONENT SIDE			SOLDER SIDE
	1	1A	1В
		2A	2B
Out	SPEAKER	3A	3В	GND
In	HOLD 1 SW	4A	4В	BILL ACCEPTOR 1	In
In	HOLD 2 SW	5A	5В	BILL ACCEPTOR 2	In
In	HOLD 3 SW	6A	6В	BILL ACCEPTOR 3	In
In	HOLD 4 SW	7A	7В	BILL ACCEPTOR 4	In
In	HOLD 5 SW	8A	8В	HOPPER INHIBIT	In
In	START SW	9A	9В		In
In	BET / DOUBLE SW	10A	10В		In
In	reserve	11A	11В		In
In	reserve	12A	12В		In
In	reserve	13A	13В		In
In	MAXBETSW	14A	14В		In
In	HELPSW	15A	15В		In
In	FRONT DOOR SW	16A	16В		In
In	BACK DOOR SW	17A	17В		In
In	COIN A	18A	18В	COIN В	In
In	COIN C	19A	19В	COIND	In
In	(short) STATISTIC SW	20A	20В	SERVICE SW (long statistic)	In
In	PAY OUT SW	21A	21В	KEY OUT SW	In
Out		22A	22В	HOPPER COIN SW	In
Out	COIN + BILL COUNTER	23A	23В	COIN LOCK	Out
Out	KEY IN COUNTER	24A	24В	BELL ACCEPTOR LOCK	Out
Out	TOTAL IN COUNTER	25A	25В	UPPER LAMP GREEN	Out
Out	TOTAL OUT COUNTER	26A	26В	UPPER LAMP RED	Out
Out	KEY OUT COUNTER	27A	27В	UPPER LAMP YELLOW	Out
Out		28A	28В	TOTAL BET COUNTER	Out
Out	HOLD 1 LAMP	29A	29В	BET /DOUBLE LAMP	Out
Out	HOLD 2 LAMP	30A	ЗОВ	MAXBETLAMP	Out
Out	HOLD 3 LAMP	31A	31В	PAYOUT LAMP	Out
Out	HOLD 4 LAMP	32A	32В		Out
Out	HOLD 5 LAMP	33A	33В	HOPPER MOTOR	Out
Out	START LAMP	34A	34В	HELP LAMP	Out
In	KEYINSW	35A	35В		In
	GND	36A	36В	GND