707svc 07

Nom suppose that TR-707 is to run with 6ASS DRUM 1(BO-1) being selected. the CPU IC5 put* XSTO fCHO start) and XSTA (XST0-XST7 cnable) Iow, resetting counter 0. presetting it to the starting address 0000H and allowing it to count the clock pulse XCK0 from pin B m discrete steps. The counter continues counting until it inerements up to 1FFFH and topi there until the next trigger pulse is received. While counting. the contents (a groop of 13 clock pulscs) of the counter is transferred to mkfałł selector where it is read cvery 40ps and is pre-sented along ports ADRO through ADRC—13 lower adifces bits.

IC34 and IC35, 32.768 word by 8 bit ROM. require 15 address bits to access their memory locations. Clocks A and B from IC30 serve as MSBs while C indicates which oneoftwo ROMs is to be selected—ChipSelect.

On dse contrary. LSB AORO is defeated when particular v<Mce is selected: BO I and 8D-2 share the same memory area «ith even addresses allocated to BD-1 and odd ones to 80-2 as shown in Table 1. With BD-1, data selector IC33 blocks AORO and passes "O” data from IC32 onto AO of ROM IC35. With BD-2. IC33 selects "V*. With Lom Tom. Mid Tom. Hi Tom or Hi Hat, AORO is allow-edioreach AO.

Eadi 8-bit memory focation {PCM waveform data) in ROM is loaded mto latch IC36 on the rising edge of CLK4. This 8 bit data is. it converted to analog equiva-lent by 0/A corwerier IC37 as it is. not restored to its original amplitudę. A certam techmc is involved during PCM to improve S/N ratio. to have higher resoiution. etc. A signal coming from Envelope Generator into (♦) REF pin gives right tonę contour to a continual PCM wwrlorms bcing decoded and converted to an analog sond.

BASS DRUM1 ( BD-I ) 6‘SIRS flAiłKIBT. •) X    I C 30 IC X ST 0 ( -7 * v

0    * » - t ) iifSTA ( X STO-7 4 *- /*)

•). O^yCHOUOOOOHICj-t-sl :?nt;|SXCKOIC

Soi-i u tik 4? a j fRtfifsł LTfittt* cm

1    1 ty 1 • T    KlfiU 4 OASSIC

Ty - * 1,7 9IC£0 ADRO-AURCałiCH)?J? ntfi&tt. C WCtT-#XSTO

1l O stlittm 1 FFFH ICitTłŁ* \ -,-fC tlł

Łmott. )

2S6K e-, 1 ROM I C34 . 1 C35 0)A4=') . o y “ > » SIC T O    5ICIi, ISt';l• ®7 K

STT. «BOMSB2t v HCIi I C 30 O A . B 7 o tr.    en. iib^mromicr

-JLSB AD

^R0 li. SRiCioTii ROM r KRAiLTffifflsn*

MaI*. BD-i i BD- 2lłBB ROMffl/-fc'l • X >) Tin-ftcrao. BD-1 KIJ«»©T K t-X<H BD - 2lCIX4SRT Ku-AiifflSTf.nTl'* f. ( ® 1 8KO. C0Ą, BD-1 ©*SS. BOMBAO ICliłrit "0”*l I C3 2 . I C3 3 {-aCXUlA.ini T( BD -2 ■ 1 ” ).

ROM *•*>«*!!) 3 nfc 7-7 V y ■ r- SU. IC37 ( 7 y- ■ »■. h -7-) -CTTo^EEicg:*?n

*<. Smtńliie.fmmŁltitf Lł>—SLttfA,. cnu PCM ©fflElCfcl-T S/Nlt4>»W»IPl±©ffia*f$* y -<0-7*11, IC37®M R EF icjfcniłO ENV GEN *>>i®(8%lC i o TKS S fi 1 T.

TR-727 Sound Oati ROM    TR-707 Sound Data ROM

IC M.	ton	ct	CS	VOTCC	udoi*		|C HO. I IW 1 CC	CS	VOICt	HEftOir
lOA	■HIIUKII	H		HI IOKCO	?H ADIS Ak byt*		ICIA | HHbl2SbN.il | H	k	•a$s oiun i	2K AbIS Ak by(«
	dłimw)			LOW BO«CO	1H • 1 ADIS Ak byt*		| (iMISbil) ,		uss druh t	2K • | ADIS Ak była
				MJTI HI COHCA	2H ASKS Ak byt*				SHARE DtUH 1	2H ADIS Ak byt*
		1		ortu HI COHCA	2H • 1 ADIS Ak b*tl		1		SHARE DlUH 1	2H • 1 ADIS Ak byt*
				LOV COHCA	8k byt*				IOW TOM	Bk byt*
				ni tihcau	8k b>U				NID TUK	Bk byt*
. U3S	Mimtcm	H	«	(.UH TIMlAlt	6k bvt*		(CIS . »MbmbK>2 ■ H	H	HI TOM	Bk byt*
	mim*})			WHISTIE	Bk b><«		j U(llVb*2)		HI HAT	Bk byt*
				HI ACOCO	n AttS Ak b>U			1 ttli SHOT		2h ADIS Ab byt*
		J j MW ACOCO			2n • i aohs Ak »>t«			i coh atu		2m . i aDIS Ak bt<«
		J_		CARASA H*UC»5	Jh aMS Ak bv|« IH . | ADIS Ak by<«	i.... i :		KAMO Cl Al ; Tahiouiini		2H ADIS Ak byt* 2h . | ADIS Ak b»t«

Table 1    *1

TIMING CHART

ENVELO»E GENERATOR

Data coming to latch IC31 is a combination of LEVEL and OYNAMICS (ACCENT). The »alue of LEVEL is always constant rcgardless of voice selected, while DYNAMICS varies with MIDI Velocity or ACCENT amount setting.

Although LEVEL/DYNAMICS i$ connected to all 8 ENV GGNERATORs it is allowed to enter only the transistof whose base-emitter junction, for example Q26, i$ being forward biased by a TRlG from latch IC27 or IC28 at XSTA ratę. Q26 output is then connected by 1C40 to (+) REF pin of IC37 every 40*4$ with its level riecaying accordmg to C53xR59 time constant as the success<ve BD-I data are convened to analog woltages. givmg a bass Jrum contour to the vo»ce,

The DAC output is boosted at 041 and 042 conjunction and is channclcd into the S/H which is designated by A B C codę placed at IC41 sclcct pins.

As can be seen from the timing chart, the timing of enve loping and D/A converting lag one $ht behind the memory addressmg. That is. BD' 1 sound read from ROM with chanret No. ABC-000 becomes an audible sound when channel No. is represented by ABC=100, This is because the data accessed on a po$itive going CLK4 with ABC=000 is latched into IC36 on the next CLK4 with ABC-100. Consequcntly, TRlG data to ICs 27 and 28. and L EVEL/DYNAMICS data to tC31 are madę to delay one ClK4 tycie to keep pace with D/A conversiun at IC37

XSTA(SXT0-7<ł-7’«-)li I C30 ©7 Ku ?7*1C27. 28

OC KIC fcJDLin, BD-1

E N V GENOQ2 6 iJTR 1 G'"•/i-^ICi oTrariBL. LEVEL i DYNAMICS! ACCENT)©S£ ? CS3lCXZ2tltt. <tii. LEVELO(aiJ ifflifffiOIS ft-CfeSlC-ffiT-r.* ti. LEV El. / DYNAM I CS CVIi 8 $.±Tt» 1 5 :/ v * 9 IC B1W1 ? tl t tt>T R IC“'M I i ■/ V *?ic©4ic jLM,* t. Q 2 6 OtUfili 1 C3 98 4-iBD. I C4 0 ICi D/A    REF    tłlOL «

rt>UC53xR96 GUMKI IC £■ LT«S L T fi 8 * T. Ui&tMBDnWy K • f'-#*Ui<ROM**i»K*Hi ?n4B5CU 7ii< 4«icassnTi>» t. il IC10«7Kux.    ®f • /*»*94

I C 4 0 / 4 1 © + ' 7 ł    l'JT. c

nil ROM 7)7 7/    T 7 4- A    •)

C L K 4 © I -M ntOłllT I C 3 6 ic 7 7 f- Słl D/AS«f*n4J&|Tr. UdliTTRir. JJ-tW I. E V li l. / DYNAM I CS 7 - 9 <,r W&HftTlh 112 II ł V.

6