Schematic
A 27-page schematic of the programmable Sony SOBAX 2500 of 1969-70: the 362 cm longitudinal delay line, the phase-locked master clock, Sony 500-series logic and the multiplexed Hitachi CD-81 Nixie display.
Sony SOBAX 2500 Calculator Schematic Contents Section Page Title & Contents (this page) 1 Notes 2 Block Diagram 3 Timing (Clock) & Initialisation 4 Timing (Channel & Bit) 5 Timing (Digit) 6 Keyboard 7 Digits F & Fp 8 EXEC & OVF Flags 9 SM - Supervisor State Machine 10 PM - Proc. Machine - Bits 1,2,4 11 PM - Proc. Machine - Bits 8,10 & PNEWN 12 PM - Proc. Machine - State Decode 13 Misc. Flags 14 CJ Counter 15 CK & DP Counters 16 SPC - Program Counter 17 Digit M 18 Digit N 19 Digit X Gating 20 Digit X 21 Digit Y 22 Registers A,B,T,S Gating 23 Register D Gating 24 Registers A,B,D,T,S 25 Display 26 Power Supply & Unused Gates 27 Sony SOBAX 2500 Calculator Section: Title & Contents Page: 1 Rendition: Jun 22, 2025 Appendix Section Timing Diagram Timing Block Diagram & ADL Sync Delay Line Timing Delay Line Organisation SM State Graph PM State Graph - Main PM State Graph - Arithmetic Bit Codes, IC Pinouts & Substitutes Board Layout & Test Points Connectors Signal Names Page 1 2 3 4 5 6 7 8 9 10 11 This schematic has been derived through reverse engineering. This is not the manufacter’s schematic, nor based on the manufacturer’s schematic. Notes • The symbol • with no voltage specified denotes V+4. connection between different sections. connection limited to same section. Arrows indicate direction of signal or energy flow. • ‘~’ at the end of a symbol name indicates the logical NOT operation. • The Acoustic Delay Line is based on magnetostrictive principles. See the article “Magnetostrictive Delay Lines” in “Electronics World”, Jan. 1964. • These drawings based on unit with Serial No. 620173 which contains a Board F marked with 1-539-224-12. Component values marked with “*” are the values for Board F marked with 1-539-224-11. Log • 1999 Sep-Nov: Initial drawing / bhilpert. • 2005 Feb: ADLRD source corrected, comes from Q7 rather than Q8. Corrections to labels on flip-flops in display page. • 2005 Feb: Some additional labeling of “*” components for board F. • 2014 May: Backplane connectors correction for V+4/GND, numeric key coupling distinguished, other minor reorganisation. • 2024 Feb: Reorganisation for state derivation. • 2024 Fall: Addition of state information, signals renamed to more appropriate names. Sony SOBAX 2500 Calculator Section: Notes Page: 2 Rendition: Jun 22, 2025 Keyboard mode switches, C-ALL, C-ENT, <, >, DP, CHG-SIGN keys Keyboard Function Keys KF.8 KF.4 KF.2 KF.1 RP Digit DF F.8 F.4 SPC Counter SPr | SPd F.1 Fp.8 Fp.4 Fp.2 Fp.1 Supervisor Layer Procedure Layer Control SM.1 SM.2 SM.4 PM.1 PM.2 PM.4 PM.8 PM.10 OVF Power Supply RP to all sections to all sections Counter CJ Counter CK Keyboard Numeral Keys KN.W KN.4 KN.2 KN.1 EXEC PNEWN INTØ SST PNEG RNDØ SNML PNEWN2 RDNEG SMSET PDPE RDD=0 SPARM PPHE SSKIP DP Counter Digit DG F.2 Timing DF RDw PPH2 PQPA Register RD DX RAw DN RB RT RS Register RA RA PQRDØ Digit DN RA RACOMP RDCOMP RP RACOMP DXwa DXwb DN DN Digit DX Adder DX RACOMP RDCOMP DXpW DXp4 DXp2 DXp1 DY DM Display Latch to all sections RBw RA DX DN DF RSw 16 digit register Rendition: Jun 22, 2025 RTw DX Registers RS RM1 RM2 RM3 RM4 RM5 RP7 RM6 RP6 RM7 RP5 RP4 RP3 RP2 RP1 4-bit register Sony SOBAX 2500 Calculator Register RB Digit DY +1, –1 RB 1bit Section: Block Diagram Page: 3 RDCOMP RACOMP Register RT RS RP RT DN Digit DM DY DM Nixie Display Coarse Phase Comparator ØS10 ØEON EON capture 4 x10 ØS ØS0 2K F303 8 11 12 7 J F305 Q Nf22 5 9 G INIT Ø Nf20 K Q~ 2 1 6 10 J F305 Q Nf12 Charge Pump 4 G 560 Ø K Q~ Nf14 TNUPCp 3 TNRDY 5 22K CF4 47µ/16V 9 x7,8 F306 TNUPC 11 F306 x1,2,12 1K QF14,*13 CS1303 3 RF48 120K 6 QF1 C634A 10K TF14 INIT ØEON ØS10 channel capture ØS14 ØS~ 8 5.6K *6.2K 10 7 F307 20p 6 9 QF12 C641 20p TF12 TNUPF 5.6K *6.2K 4 F306 x10 ØB3 ØS10 normal operaton ØS14 ØS~ QF17 C634A 680 *620 1K 18K 68n 1S 332 47µ 16V 680 *620 18K 75p 100p QF18 C641 QF13,*15 C641 27K 27K 4.7K 5 V–10 QF9 C641 Buffer 11 1 15K 4 2 F307 1K 30p 560 5 12 QF10 C641 560 TF15 9 15n NF8,10 NE7,9 ØS QF28,*25 C1063 220 QF31,*30 C641 820 10 7 F308 Tf5 100 150 QF33,*32 C641 5.6K 75p 3 INIT~ TNV QF19 C318A RF45 4.7K *4.3K 820 QF16 C634A RF44 100K CF24 220µ/16V Fine Phase Comparator 820 Tf10 QF15,*14 CS1303 10K ADLRD Master Clock ØS~ 30p 6 8 QF11 C641 8.2K 4 2 3 11 F308 5 Power-On-Initialisation 12 1 3.3µ 25V Power-Off-Discharge POWER (closes when unit is turned off) V+200 100K 100K 24K 10µ 160V NF23,25 CF34 47µ/16V 22 20K* CF38 5µ/150V 27K *24K 2.7K *2.4K 68 Sony SOBAX 2500 Calculator Section: Timing (Clock) & Initialisation Page: 4 Rendition: Jun 22, 2025 V–10 PWROFFP to main registers 3 4 5 6 QF23,*28 C634A Tf3 F304 2 NF16 NA13 INIT~ ND21 7 7,8 F309 x9 QF20 C634A INIT 6 5 6 V–10 Tf9 Tf7 V–10 68 ØD0 ØB0 4 3 7 F310 NF12 NE11 2 NB10 INITP~ 8 11 12 ØS 7 F401 Q J G 5 9 2 f44 Ø K Q~ 1 ØS 6 10 J F401 Q 8 4 G Ø K ØS Q~ 2 1 ØS 6 J E114 Q 5 9 2 G Ø K ØS Q~ 1 6 10 J F402 Q 8 4 11 G Ø K ØS Q~ 12 7 3 J F403 Q 5 9 2 G Ø K ØS Q~ 1 6 10 J F403 Q G f30 Ø K 4 Q~ 3 NF15 NF24 NF26 NE15 NE23 NE25 ØS1 DE5 8 11 ØS Q~ F402 Q NE17 G K 7 J NF18 4 Ø 12 3 ØS0 5 11 12 7 3 J E114 Q DE7 9 Ø ØS Q~ ØS6 5 2 G K ØS2 1 6 10 J E113 Q DE9 4 K ØS Q~ ØS7 8 11 G Ø ØS3 3 12 7 J E113 Q DE11 9 Ø ØS8 ØS Q~ 5 2 G K ØS4 1 6 10 J E112 Q ØS5 DE8 4 11 G Ø K ØS9 ØS Q~ 8 12 7 3 J E112 Q DE10 9 2 G Ø K ØS Q~ 5 1 6 10 J E110 Q DE6 8 4 11 G Ø K 12 ØS Q~ 7 3 J E110 Q DE4 9 2 G Ø ØS K Q~ 5 1 6 10 J E109 Q DE13 4 11 G Ø K 12 ØS Q~ 8 7 3 NE21 NE19 NF22 NF20 ØS10 ØS11 ØS12 ØS13 J E109 Q TE27 9 G Ø K Q~ 10 ØS14 ØS15 TC46 5 100 330 360* ØS0 ØS ØS5 8 11 12 7 F408 J Q Nf8 9 K Nf5 Q~ 10 47n QF25 QF26* C641 2.2K G Ø 1.5K 2 68 330 360* 68 QF29 C1063 QF32 QF33* C1063 NF5,6 NA9,10 ØB NB5,6 NC5,6 ØB 1 6 J C116 Q ØB01 G TC45 Ø TC47 K Q~ 8 4 3 11 ØB 12 7 J C116 Q ØB12 9 G Ø K Q~ ØB03 10 8 4 10 C216 ND5,6 9 10 5 NE5,6 11 C316 1 NC16 NB15 12 NKT ØB0 NF14 3 ØB~ 9 8 7 4 C216 5 6 6 C316 2 NC20 NA24 7 ØB3 NB19 NE22 NF19 Sony SOBAX 2500 Calculator Section: Timing (Channel & Bit) Page: 5 Rendition: Jun 22, 2025 NC8 NB7 ØB3~ 10 8 ØD1~ ØD3~ ØD7~ 1 ØB3 11 ØB 12 A111 11 12 7 3 A107 J Q 9 G ØB3 Ø ØB K Q~ 2 ØD12~ 5 2 1 6 10 A107 J Q 8 4 G ØB3 Ø ØB K Q~ 4~ 2~ 1~ 8 4~ 2~ 1~ 8~ 4 2~ 1~ 8 4~ 2 1~ 7 5 4 4 A101 2 NA44 NB29 3 NE40 8 NkT ØD0~ 10 11 8~ 4~ A101 ØD1~ 1 7 8 6 4 4~ A102 2 NA42 NkU ØD2~ 3 8 9 11 2~ 1 8 10 2 1~ 12 5 2~ 1 9 4 A102 1 12 ØD3~ 7 2~ 1~ 5 9 G ØB3 Ø ØB K Q~ 4 4~ 8~ 6 12 3 8 8~ 8~ 11 A106 J Q 4 A103 2 NA40 NkV ØD4~ 8 9 11 4~ A103 1 ØD5~ 7 8 6 4 4 A104 2 ØD6~ 3 8 9 11 2~ 1 8 10 2 1 12 5 2 1~ 8 4 A104 1 12 ØD7~ B308 DB1 5 5 2 ØB3 1 ØB 4 6 G J B105 Q TB12 4 G Ø K Q~ ØDEXT~ 3 Ø K Q~ 3 NB37 NB18 NA36 NA17 1 1~ 8~ 3 10 6 x4 2 2~ 6 4 1 10 7 5 2 A106 J Q PNCEXT 2 1~ 7 7 6 5 4 8 A105 2 ØD8~ 2 3 1 8 9 10 11 8~ A105 1 ØD9~ 1 7 6 4 8~ A108 2 ØD10~ 3 1 9 11 12 4~ 2 8 10 4 2 12 5 4 8~ A108 1 ØD11~ 4~ 2~ 1 6 5 4 A109 ØD12~ 2 3 8 8 9 10 11 9 A109 ØD13~ 1 10 ØD0~ 11 E315 1 NE31 NB43 12 12 NC26 7 3 NF32 6 4 5 4 A110 ØD14~ 2 5 ØD15~ 6 3 11 9 11 12 2 NE20 NB21 7 8 10 E316 ØD15 A110 1 NA22 NB22 NC21 NE24 ØD15~ ØB3 9 10 NC22 4 E316 5 1 6 7 E315 2 NE8 NB8 Sony SOBAX 2500 Calculator Rendition: Jun 22, 2025 ØEON ND7 NF17 NKV Section: Timing (Digit) Page: 6 ØD15 3 12 8 ØD0 Tf4 CHECK OPER NA11 NK18 Ne32 6 KCHECK~ NF37 Nc34 NK1 LEARN AUTO MAN NK5 + KCHECK Nk17 NF41 Ne21 Nk16 Ne30 NkS Nd5 Ne6 NK15 = KAUTO~ KMAN~ M READ T OFF Nk13 ND27 4 NE28 5 1K 33µ 10V M8 6 15K u 5/4 d 3.9 ØD0~ ØD2~ ØD4~ 0 2 4 KTREAD~ KTREAD KTON Nb42 NkA Nb4 NkE PS~ Q~ PJ~ Nc41 Nk18 M2 PD~ PJ~ NK13 11 9 5 M4 KF.2 1 10 6 3 4 7 MC~ M3 KF.4 2 5 11 1 M1 2 4 x10 3 M1 5 12 11 9 E~ 8 10 MS~ KRØD~ M2 8 Q~ KRDWN~ 4 x10 12 M~ MO~ 3 1 S~ M3 1 KF.8 12 PS~ 1K 33µ 10V 1K 33µ 10V Nd42 KCA~ 15K 0 1K CE 33µ 10V 15K 9 8 15K M5 7 Nd12 6 KCE Nb14 Nk14 9 CS 8 Nk11 7 KSL~ M7 Nb10 6 Nd4 4 D410 10 KSCS Nd15 Ne16 Nb12 Nk15 NkB KSR~ KDP~ Rendition: Jun 22, 2025 15n 6~ 120K Backplane 1-539-225-12 (Unit SN 620175) 7~ 9~ 2~ 5~ 8~ 9~ 4~ 6~ 7~ 8~ Nk10 9 3.3K 5~ Nk1 Nk2 Sony SOBAX 2500 Calculator 4~ Nk7 8 5~ 3~ Nk9 KSCS~ 7 > 3~ Nk4 5 6 5 2~ Nk8 4 10 1~ Nk3 3 1~ 3~ Nk6 2 NK2 0~ Nk5 1 < Section: Keyboard Page: 7 2 KPS~ CA DP 11 PD~ D~ KF.1 2 3 MS~ A~ M4 12 A~ R~ NK9 J KR54~ NKU MC~ NK3 D Nk12 MO~ NK4 S M~ MI~ NK14 Mc 7 MI~ NK17 Mout 2 NE38 NKS 5 MS~ NK8 Min 7 S~ R~ NK7 NkR NkP Q~ NK12 R 68n E~ NK6 √ KEDIT D~ 4 R~ MC~ D~ ÷ 510 3 M~ NK16 KLEARN~ 4 D301 10 S~ NK10 × Nd31 A~ NK11 – 5 E~ 9~ 10 • 510K 68n Backplane 1-539-225-11 (Unit SN 620173) 7~ 8~ 9~ 0~ 5~ 6~ 7~ 8~ 9~ 8 9 10 12 M6 Ne41 1 KN.1 11 7 6 5 3 M6 Ne39 2 KN.2 4 8 12 11 9 M8 Ne37 1 KN.4 10 11 12 1 2 4 3 M7 Ne35 5 KN.W SM.4~ SM.2 10 4 E408 5 Nd33 12 (Px0+x1)~ (P13+17)~ SM.1~ D405 TD11 11 KCA~ 1 5 D406 3 2 TD2 3 7,8,9 5 D202 6 2 1 ØB 9 12 8 2 D403 D403 P17~ 4 D109 PM.4 11 7 10 P13+17 2 1 12 INIT~ Ne34 6 6 Nd36 Nb34 11 10 SNML~ 6 D103 Q 8 4 11 G F.8 Ø K Q~ ØB 3 12 7 J D103 Q TD4 5 9 2 G F.4 Ø K Q~ 10 ØB 1 6 J D102 Q TD3 8 4 11 G F.2 Ø K Q~ ØB 3 12 7 J D102 Q TD1 5 9 2 G F.1 Ø K Q~ ØB 10 1 6 J D106 Q 8 4 11 G Ø K ØB Q~ 3 12 7 J D106 Q 5 9 2 G Fp.4 Ø K Q~ ØB 10 1 6 J D105 Q 8 4 11 G Fp.2 ØB Ø K Q~ 3 5 8 9 KF.8 7 M2 6 F.8~ F.4~ F.2~ F.1~ Nd35 Nd37 Nd39 Nd41 NE29 Fp.8~ KF.2 510 KF.1 KAUTO~ SNML~ EXEC~ OVF~ 8 KF.4 KF.4 7 8 9 E303 10 6 CE2 68n 9 C634 NE42 M1 6 1 4.3K 2 220n Ne33 4 E401 5 10 KSCS~ 11 KF.2 M5 3 12 4 DE2 10 KF.1 M5 5 3 F.1~ F.2~ F.4~ F.8~ Px2+x3+x6+x7 F.1 F.2~ F.4 P09~ F.2 F.4~ F.8 11 KCE 12 1 D401 4,10 3 D401 DF=0 5 2 PM.4~ F.2 8 Nd40 Nc39 6 (PFMC+RV)~ F.4 9 IDLE~ F.1 11 F.2~ 1 2 D202 PM.2~ SM.1~ 10 7 D101 3 12 4,10 D202 5 Nd34 Nc33 Nd22 Nb22 PFSR~ PFSR F.4~ KTREAD~ P09~ F.2~ F.4 F.8 Sony SOBAX 2500 Calculator Section: Digits F & Fp Page: 8 Rendition: Jun 22, 2025 7 D105 Q TD13 9 G TD12 Ø K Q~ 10 Fp.1~ 7 KF.8 12 J RPF~ Ne38 4 E402 RP 1 J TD6 P02+03 F.8~ 12 INIT~ 2 11 D211 4 10 4 D411 3 5 5 1 6 D207 2 Nd11 Nc11 7 PFCE~ Ne12 9 8 7 D302 7 6 8 9 2 12 11 D204 4,10 3 D204 D204 PFARITH 6 5 11 10 12 1 D402 4 3 2 D402 PFEQ ND13 1 7 5 (P13+17)~ 8 9 D402 6 Nd38 Nc37 PFRECALL~ 7 9 8 E411 6 ((P02+03)•MCI)~ SPOVF 8 P18 7 ØD15 10 E407 DN 6 9 1 P11+16 12 PFSR 11 D407 RDNEG 3 Ne9 2 Nd6 12 PFSR~ Nc5 1 Fp.8~ 11 D411 (P11+18+1C)•PQPA RA Px2+x3+x6+x7 3 2 10 12 4 C204 5 2 ØD15 1 C413 ØB0 3 11 XOVF 11 (P11+18+1C)•PQPA 8 12 RDD>0 2 C416 ØD15 11 3 1 DY PFCE~ 7,8 9 ØB C203 12 7 6 C103 Q J TC11 G TC8 Ø K OVF 9 Q~ NC44 NA32 10 ND43 OVF~ NE44 DF=0 DD1 DD3 DD2 KSCS~ KTREAD~ KPS~ DN=0~ 4.7K 33K KLEARN~ 10µ 25V 10µ 25V QF22 QF21* C634A KCHECK~ 10K 4 x10 F309 4 E204 x10 1 5 NF43 OVF~ 5 NF44 2.7K 2 11 F309 Nd1 Ne26 3 1.5K 1µ 50V 12 NE43 9 E203 QF24 QF23* C634A 10 OVF~ S6 SNML~ SSKIP~ F.1~ F.2~ F.4~ MSETMAN~ P18 KAUTO~ SM.2 SM.4~ Sony SOBAX 2500 Calculator Section: EXEC & OVF Flags Page: 9 Rendition: Jun 22, 2025 KAUTO~ PM.2~ PM.4~ PM.10 KSCS~ 4 (KCHECK•S6)~ 12 11 3 D201 7 NF42 Ne11 PFCE~ SADDEOP 8 6 1 ØB 2 ØEON ØB 12 4 11 E203 5 8 11 12 7 J E103 Q Ne31 Nb33 9 EXEC G Ø K TE6 Q~ 10 EXEC~ 3 SM.1~ Nd14 Ne17 SM.2~ 5 1 P09~ 2 4 E404 10 5 12 2 11 E406 3 1 5 8 9 7 E304 6 ØEON 2 12 11 E304 1 IDLE 3 9 8 7 B306 6 IDLE~ Nd9 Nb16 10 4 E304 Ne10 4 B404 10 4 E406 x10 7,8 E406 9 5 IDLE 5 6 (IDLE•ØEON)~ KSCS SST 11 SADDEOP 12 SST 1 D410 KMAN~ KCHECK~ SNML~ DN=0~ 4,10 (KSCS•SST)~ 6 2 Nd13 Ne14 E206 5 2 7 9 8 IDLE E306 7 8 9 E305 1 6 2 1 11 12 12 11 E306 3 SPARM 2 SM.2 6 11 PFCE~ 11 12 E404 NUMNML~ 3 10 1 2 E305 1 4 E305 3 10 E205 KCHECK~ F.8 8 KTREAD~ 9 why?S6 D301 7 9 ØB E206 6 F.4~ S6 2 SSKIP~ 11 1 12 D301 SM.4~ 3 Nd21 Ne22 9 9 E205 SM.4 6 PFCE~ 12 E205 3 2 8 11 ØEON ØB 2 SMSET~ TE11 SM.1 4 SM.1~ Ø K Q~ SM.1~ 11 12 7 J E105 Q 3 Ne20 Nb24 9 ND9 SM.1~ SM.1~ SM.4 SM.2 KCHECK SM.2~ SM.4 SM.4 KCHECK~ SNML~ Ø TE13 K Q~ J E103 Q SMSET SM.4~ 10 4 1 why? 2 Nd23 Ne24 11 8 7 SNMLp 9 F.8 1 D406 6 E204 ØEON 9 S6~ PFCE~ 8 KLEARN~ 7 S6 F.1 F.2 F.4~ F.8~ 8 P18~ D407 Sony SOBAX 2500 Calculator E204 4 6 5 D407 10 SM.2 4 D408 SMSET Ø K TE7 Q~ SMSET~ 3 µS Flag DD5 8 ØEON ØB 2 5 6 5 MSETMAN~ 1 10 1 TE8 4 G 6 DD4 D216 2 10 4 6 PFCE~ Section: SM - Supervisor State Machine Page: 10 Rendition: Jun 22, 2025 7 ØB DE3 10 7 9 D104 9 RDNEG 5 3 12 8 11 B203 5 Nb25 NF29 D408 3 12 SPARM 11 12 7 J D112 Q Nd27 Ne28 9 G Ø K TD33 Q~ 7,8 E413 9 10 6 SM.1 4 10 E306 5 S6~ Ne18 Nb18 Nd17 SM.1~ Ne15 Nc17 G 5 S6 4,10 G TE10 E104 8 J Q 9 NE10 11 ØEON G 12 ØB Ø TE9 7 K Q~ 10 6 7 12 E403 6 E104 Q Nd19 3 SNML 1 J Nc21 1 8 10 E403 2 6 11 KAUTO~ 7 ØEON 8 8 5 12 F.1 5 3 7 4 5 E206 SPARM DE19 KMAN~ SSKIP~ SPARM,SSKIP~ 4 10 2,11 12,H1 11 D302 E401 S6 5 3 12 2 C403 3 Nc42 Ne40 6 Ne4 1 (KCHECK•S6)~ 7 8 9 E404 Nd3 MSETMAN~ PM.1~ PM.2~ PM.10 PQPA PFCE~ PFSR~ PM.4~ PM.8~ P0D DYINC DY.W PM.2~ PM.4 PM.10~ DXCA~ SM.1 SM.4~ NUMNML~ SM.1 SM.4~ PFSR PM.4 DXCA PM.1 PM.4 PFCE~ PM.10 4 10 D316 5 PFEQ PNEWN PM.10~ PM.8~ CKHOME OVF~ 1 P0:7 NB20 ND19 2 B209 3 * (P06+07)~ PFSR~ Fp.8~ PM.4 10 4 D415 PM.2 PM.10 P0A PFARITH PNEWN Fp.4 Sony SOBAX 2500 Calculator P10+14+18+1C 12 2 D115 4,10 3 2 P18~ 11 (P06+07)~ 1 D216 (P13+17)~ (KSCS•SST)~ 7 8 C202 5 Nc26 PFCE~ (P11+18+1C)•PQPA Nd16 Nc15 12 2 D208 3 11 6 3 12 9 D115 1 1 10 ØEON 7 ØB 9 D416 6 8 2 1 5 J D114 Q 3 G Ø K ND31 NC30 PM.1 8 9 TD40 Q~ 4 PM.1~ PM.1 12 10 11 C208 1 NC28 NB27 2 NC34 NB33 PM.1~ 12 6 ND25 11 2 B311 NB24 3 1 9 8 7 E408 NE26 6 1 2 11 E408 3 12 Ne3 8 9 7 B311 NB25 6 ND26 7 9 8 D212 6 7 2 8 12 1 D316 9 3 (P13+17)~ 11 PMDQFIN 7 8 9 D316 3 12 1 2 D415 D416 D114 8 J Q 6 9 ND32 NB31 11 ØEON G NC32 12 ØB Ø TD38 7 K Q~ 10 PM.2 3 4 PM.2~ PM.2 9 6 PFCE~ C405 PM.2~ NE34 4 8 D412 9 6 PM.4~ 11 10 1 2 D412 12 6 7 5 7 8 5 11 5 PFRECALL~ Section: P Machine - Bits 1, 2, 4 Page: 11 Rendition: Jun 22, 2025 11 4 3 D412 5 ØEON ØB TD35 D112 5 J Q 4 2 G 1 Ø TD34 6 K Q~ 3 10 11 C405 1 Nc2 Nb1 2 Nd2 Nb2 PM.4 12 PM.4 3 4 PM.4 5 6 7 D116 Nc1 Ne2 PM.4~ 8 7 P11+16 PFCE~ P0A~ PNCEXT PM.1~ PPH2 CJHOME PM.1~ F.2~ F.4 F.8~ PFARITH Fp.1~ Fp.2 PNEWN (KSCS•SST)~ 2 1 ØEON 1 ØB 11 2 D209 12 8 3 D113 Q 9 TD36 PM.8~ 10 G 3 2 D302 P0A 3 D116 1 ND41 NB41 K Q~ 9 ND39 NC40 PM.8~ PM.8 PM.8 NC42 10 B310 x4 PM.8~ 5 PMDQFIN 11 4 1 10 D406 5 12 (P08+0C)~ 2 DY=9~ 11 1 D110 (P01+05+07+11+13+17)~ 3 12 P1E CJHOME~ DY=9~ PM.2~ PM.8 PFSR~ SST 1 PFCE~ 11 P1D~ NC15 ND16 12 C414 3 P18~ 2 8 2 11 3 D415 3 5 12 ØEON 2 ØB 3 2 1 6 12 4 D414 J D113 Q 4 TD37 PM.10 PM.10~ 4 G 9 D414 K Q~ 3 ND37 NC38 PM.10~ PM.10 NE42 5 1 11 ND24 NC23 6 (PFSR~•SST•x)~ 7 PM.8~ PFEQ Fp.2 P0A PNEWN2 1 2 11 D111 3 12 7 8 9 D111 6 4 P18~ 10 5 D111 5 KSCS~ ØB P11+16 2 1 6 J D108 Q 4 G Nd32 Nb31 PNEWN Nc31 Ø K 5 6 C208 2 NC36 NB35 Q~ 3 Nd30 Nb32 Nc29 PNEWN~ 10 B311 x4 PM.10 NE36 7 Ø Px8+x9+xC+xD 10 PM.1~ Sony SOBAX 2500 Calculator 11 1 11 PPH2~ Section: P Machine - Bits 8, 10 Page: 12 Rendition: Jun 22, 2025 10 12 Ø 12 Nb20 Nd20 12 B404 11 J TB26 5 PM.10~ PM.1 PM.4~ PM.8 PM.2~ PM.4~ PM.8~ PM.4~ PM.8 PM.10 PM.2 PM.8 PM.10 PM.1 PM.2 PM.8 PM.2 PM.4~ PM.8 PM.1~ PM.2~ PM.8 PM.10~ PM.1 PM.2~ PM.4 PM.10~ PM.2~ PM.4 PM.8~ PM.10 PM.1 9 7 8 D216 (Px9+xB)~ 6 ND44 NC43 7 C408 9 8 7 6 NC27 ND28 TD39 8 D211 6 (P18+19+1A+1B)~ 4,10 D211 5 8 (P14+15)~ (Px0+x1)~ PM.2 2 12 NC35 ND36 C407 11 3 10 TC27 4 C411 5 Nb8 C411 (P1A+1B+1E+1F)~ 6 C406 2,11 12,H1 C411 TC12 11 8,9 x7 C407 12 C404 3 6 7,8 9 D410 3 1 4,10 D212 P0A 6 Nd10 5 1 C408 Nb11 Nc12 2 3 10 x4 C408 P05+0D 5 4 2 5 Nb9 P14+15 7 8 9 10 x4 D403 5 3 2 4 1 10 12 PM.8 PM.10 2 D214 8 1 12 C409 9 (Px2+x3+x6+x7)~ P02+03 (P13+17)~ (P13+17)~ ND42 NC41 P13+17 D315 P11+16+19 5 ND8 NC7 (P11+19)~ P16~ P11+16 P11~ TC17 C410 6 P1C~ 2 1 C409 5 3 C410 NC39 ND40 3 12 6 3 10 C409 4 x10 C214 5 Nc19 Ne19 P02+03+04+05+06+07 +0C+0D+0E+0F +12+13+14+15+16+17 +1E+1F 2 4 Sony SOBAX 2500 Calculator Section: P Machine - State Decode Page: 13 Rendition: Jun 22, 2025 11 C402 ND12 NC11 11 PM.2~ (P02+03)~ 11 PM.10 7 ND29 NE30 ND10 1 D315 PM.4~ (P14+15)~ PM.4 5 Nc7 12 PM.10 PM.1~ D214 11 PM.1~ PM.2~ C407 NC9 4 10 P08+0C 12 1 C412 Px2+x3+x6+x7 Nc10 4 10 P13+17 PM.1 10 x4 6 3 11 3 Nd8 D214 (P08+0C)~ P0D 5 (P06+07)~ 6 6 Px2+x3+x6+x7 11 2 C406 7 PM.4 12 D315 7 PM.10 12 2 D212 8 Px2+x3+x6+x7 PM.1 TD20 Px2+x3+x6+x7 9 PM.4~ P0A~ NC37 ND38 11 NC29 ND30 P0F (PxA+xB)~ 1 7 PM.10~ TC32 2 9 Px2+x3+x6+x7 P0F~ 1 8 PM.4 PM.10~ P1E (PxB+xF)~ 6 C412 P18 P1E~ 3 (Px2+x3+x6+x7)~ 8,9 10,11,12 P18~ Nd7 (P01+05+07+11+13+17)~ 1 Ne8 7 9 (P02+03)~ PM.8~ 7 9 P09~ NE41 8 9 PM.8~ 5 Nc8 Nb7 P1D~ P1D PNCEXT 7 IDLE 8 EXEC SM start: 9 ØEON PM.8 PFSR PxA+xB+xE+xF: PM.4 3 PM.8 1 PM.2 UNITØD~ ØB3 CJHOME 4 12 PM.2 PM.4~ PxA+xB: PM.8 ØB3 KRØD~ UNITØD~ 10 6 7 Nb17 Nd18 2 B303 10 B304 5 8 5 11 11 1 ØB 8 7 (IDLE•ØEON)~ 9 B204 12 7 B104 Q J Nb26 Nd24 9 Ne23 Q~ Nb23 Nc24 10 8 PM.4~ 6 7 UNITØD 2 9 B303 12 6 ØB3 PNEWN2,PPHE PPHE~ B402 4 B205 6 5 5 2 ØB xx0xx ØEON 1 6 B104 Q J TB10 INTØ 4 G Ø K Q~ 3 Nb21 Nc22 INTØ~,PQRDØ~ 3 1 8 PM.4 7 PM.8~ 3 x10xx 10 11 B403 9 2 x01xx B205 10 6 KRØD~ 4 B305 5 RNDØ 5 S6 F.1~ 8 PM.8~ 9 PM.10~ 7 D201 F.2 6 DF=0 7 9 SST D209 B305 6 µD Flag 8 RD DB2 11 PM.8 PPHE 4 D208 RA 5 7 P11+16 9 PM.4 8 RDNEG D115 UNITØD TD14 PM.4~ 8 7 D208 SNMLp 6 µB Flag 8 5 7 9 8 D205 2 ØB 11 ØB3 12 B305 12 7 B105 Q J 9 G Nb27 Nc28 RDD>0,PPH2 Ø K Q~ 10 Nb29 Nc30 RDD=0,PPH2~ 3 1 9 6 4 6 S6~ P11~ 2 ØEON 1 ØB 11 D205 3 11 12 7 J D107 Q P0A~ 9 G Nd26 Nc25 SNML,PNEG 1 D413 x2,11,12 10 (P01+05+07+11+13+17)~ 4 Q~ 12 10 Nd25 Nb37 SNML 6 Fp.1~ SNML~,PNEG~ Fp.2 Fp.8~ SNML~ PNEG P13+17 Sony SOBAX 2500 Calculator Rendition: Jun 22, 2025 5 PFARITH Nc23 7,8 E401 9 D209 3 1 Ne25 Ø K PM.10 8 Section: Misc. Flags Page: 14 8 DB3 PM.10 6 10 P0A P16~ 7 8 KEDIT 10 D205 9 ØB3~ 10 F.4~ DX µØ Flag 9 PM.8 PBRD~ PM.4 Px2+x3+x6+x7 4,10 6 D109 SST,PQPA 7 12 B204 D110 D108 J Q 9 6 Nd29 Nb30 11 ØEON G 12 ØB Ø Nd28 Nb28 7 K Q~ D110 5 10 Nc27 8 PQRDLØD~ Ø K 7 PM.10 G 8 9 µC Flag 9 PFRECALL~ 11 PM.10 B204 8 B404 3 8 1 PM.4~ 4 7 10 PM.2~ P10+11+18+19: 9 µA Flag 4 3 8 x11xx 12 PM.4 INITP~ SM start: 2 D109 PNEWN 11 B304 ØEON 11 F.4 6 2 PM.8 PxC+xD+xE+xF: B304 12 PM.4 1 (P02+03)~ 9 7 PNEWN 2 4 3 D104 5 11 12 8 CHGSGN~ D408 6 7 9 TD18 D405 11 10 D405 ØB 8 4 9 5 P18~ PFCE~ 10 12 5 6 ØEON D207 1 2 1 6 J D107 Q 4 G TD19 Ø K ND20 NA18 Q~ 3 NC19 RDNEG KCHECK LIST, EDIT function display SM.4 (KCHECK•S6)~ P08+0C PM.4~ NML-ENTRY fraction increment P08+0C NML-ENTRY init PM.1~ 10 x4 PM.4~ PNEWN~ INTØ B301 zero-blanking assess 5 PM.2~ PM.8~ PM.10~ RDD=0 INTØ zero-blanking 9 PM.8~ 8 RDD=0 B403 7 INTØ MLT,DIV,SQR PM.4~ PM.10 6 PM.8 PM.10 PPHE PPH2~ PM.8 MLT,DIV,SQR PM.10 PPHE~ ØD15~ PM.1~ go home PM.8~ 8 ØB0 P08 7 S6~ 9 B401 6 10 3 ØD15 P00x01 PDPE 10 TB2 9 7 B201 8 7 9 8 S5+7 C403 6 Nc40 11 P08 4 Nb39 3 12 B201 5 2 1 9 12 6 ØDEXT~ ØB3 4 8 2 11 B202 7 TB8 B101 6 3 1 1 2 B401 5 12 11 9 8 7 12 P1x0xx B302 6 4 P11xxx 4 11 2 B302 3 SM.1 1 1 10 RPF~ 10 B402 RB1 1K 5 B403 5 5 2 ØB 8 B203 6 1 6 J B103 Q TB7 8 4 11 G Ø K Q~ TB9 3 ØB 12 7 J B103 Q TB6 5 9 2 G Ø K ØB Q~ 10 8~ 1 6 J B102 Q 2 K Q~ 12 7 3 4 4~ B102 Q J TB4 9 G Ø K TB3 Q~ 10 2 1 1~ 4 10 B302 1~ 5 12 9 7 8 Px0xx0 B301 6 4 2 8 4 10 B202 7 5 9 1~ 2 1 Sony SOBAX 2500 Calculator Rendition: Jun 22, 2025 7 B203 2 B203 3 12 1 4~ 9 6 1 2 8~ B202 11 4 Section: Counter CJ Page: 15 11 ØB SM.1~ 3 8 G Ø P11xxx 11 B301 TB5 4 11 TB1 12 1 B101 2 3 4 x10 B101 5 Nb19 CJHOME Nc20 10 x4 C110 5 CJHOME~ 4 SM.1 10 B307 7 5 9 ØDEXT~ 8 (IDLE•ØEON)~ 8,9 x7 ØB3~ B206 B208 TB23 6 6 5 2 ØB 1 6 J B110 Q TB29 11 G TB28 ØB Ø K 8 4 Q~ 12 7 3 J B110 Q 5 9 Ø ØB K Q~ 9 8 4 B210 7 8 1 6 10 8 2 2 G J B109 Q TB25 11 G Ø ØB K Q~ 2 TB31 1~ 6 KSCS KSR~ ØD0 PM.1~ KSCS KSL~ ØEON 11 B306 2 TB30 Ø K Q~ 10 2 5 9 8 7 1 B210 11 B209 6 3 12 12 11 B209 CKHOME * DPCTH 2 3 ØDEXT~ ØD15~ 1 ØB3 2 11 B205 G 10 B210 5 1 12 9 1 1~ 1 PM.1~ 7 TB24 B109 Q J 4 1 B209 12 3 4 4 x10 8 4 11 1 B206 12 TB13 4 3 10 B206 KSR~ 10 NB39 ND33 4 B306 5 5 3 12 5 2 ØB 1 6 J B108 Q TB22 4 11 G TB20 ØB Ø K Q~ 3 8 8~ INITP~ DB7 DB6 DB5 DB4 8 12 7 J B108 Q TB18 9 G K Q~ 5 2 TB19 ØB Ø CHGSGN~ 10 4 4~ 1 6 J B107 Q TB16 11 G TB17 ØB Ø K Q~ 12 7 3 J TB15 B107 Q 9 G TB14 Ø K Q~ 10 2 2~ 8 1 4~ 2 2~ 1 8 4 1 1~ 7 9 8 4~ 8~ 1~ 2~ 8 B307 RB2 1K 6 DB10 DB9 12 8 11 1 B307 9 3 2 7 B308 DP 6 12 1 2~ 4 Sony SOBAX 2500 Calculator Section: Counter CK & DP Counter Page: 16 Rendition: Jun 22, 2025 1 2 4 ØD15~ 11 2 B308 3 1 12 11 2 B208 1 3 4 x10 UNITØD~ B208 5 UNITØD 9 S6 SNML~ DF=0 KEDIT SST ØEON SM.4 SM.1 ØD15~ ØB3 INIT~ 7 8 9 KCA~ D401 6 KTREAD 8 9 7 10 x4 1 D411 4 6 ØS13 D413 5 ND11 NE12 2 4 2 ØS11 1 11 E402 TE15 ++1 10 3 4 12 E207 1 5 11 5 12 1 E207 3 2 ++15 2 reset 1 ØB 8 9 7 E207 6 E105 J Q 8 4 11 G Ø K ØB Q~ 12 7 3 6 E106 J Q 5 9 2 G Ø K ØB Q~ 1 6 10 8 E106 J Q 8 4 Ø K ØB Q~ 12 3 4 SPd 11 G 7 E107 J Q 2 TE16 ØS12 9 G TE17 Q~ 1 10 2 2~ 4~ 1 1~ ØS14 7 1~ 8 4 2 10 4 9 E307 E307 5 2 2 12 E307 4 7 9 1 1 3 10 x4 E308 1~ 6 TE12 2~ 4~ E309 ØS8 5 11 8 1~ 7 SM.4 SM.1 ØEON KEDIT SST ØB3 E208 2~ TE18 4 6 ØS10 8 7 9 E309 5 6 2 7 ++1 9 ++48 8 E402 ØB 6 1 6 J E107 Q TE20 8 4 11 G Ø K Q~ ØB TE19 3 12 7 J E108 Q 5 9 2 G Ø K ØB Q~ 10 1 6 J E108 Q TE22 SM.1 1~ 4 G Ø K TE21 Q~ 2 4~ 3 ØS9 11 4 4~ 12 4 E414 10 4 5 10 E208 5 1 reset E208 3 DE14 INITP~ 2 2 2~ 10 RP2:6,7 8 7 E210 6 9 10 RP3:3,7 7 8 E311 6 9 3 RP4:1 RE2 1K 4 11 E311 5 RPØS~ 2 12 4 RP5:0 1 2 E209 5 3 12 4 RP6:4 11 9 8 6 11 8 6 8 E212 10 1 Ø K RP1:5,7 7 1 3 E310 5 12 2 2 RP7:2 1 12 3 E210 5 11 4 1 1~ 11 SPr ((P02+03)•MCI)~ 12 2 1 4 3 SM.2 1~ 2 4~ E414 NE13 NA12 6 SP1ST 3 2 2 SM.1 8 9 1 E309 SØDATPC 7 2 4 11 E407 SPOVF 5 12 1 7 4 Sony SOBAX 2500 Calculator 2 Section: SPC - Program Counter Page: 17 Rendition: Jun 22, 2025 1~ 8 9 E209 6 10 NE14 NA14 DE12 SPEXP S6 SNML SMSET SSKIP~ IDLE ØD15 11 2 12 E216 3 1 9 4 8 10 7 E216 TE45 E216 6 7 9 IDLE SM.2 DN 8 E215 5 4 10 6 E215 TE43 2 8 5 ØB 11 12 11 12 E215 3 1 INITP~ DE17 DE16 DE15 DE18 7 J E115 Q 5 9 2 G Ø K ØB Q~ 10 A~ 1 6 J E115 Q 8 4 11 G Ø K ØB Q~ W W~ 3 12 7 J E116 Q Ø K ØB Q~ C W~ SM.1~ 1 8 9 2 E416 6 10 x4 ØS4 E416 5 4 2~ ØS8 W~ 4 ØS5 W~ 2~ 1 ØS6 W~ 2 1~ ØS7 8 7 E213 10 7 9 E313 W 4~ 2 ØS9 W 4 2~ 1~ Rendition: Jun 22, 2025 ØS10 TE47 DM 4 G Ø K TE46 Q~ 3 1 1~ KCHECK~ 6 11 4~ 10 2~ x101 8 12 W~ ØD15~ E314 9 6 8 9 10 7 E312 01xx 6 8 12 4 0x01 RE3 1K 2 11 E213 5 3 1 4 2 0x10 12 11 E312 5 3 1 4 Section: Digit M Page: 18 6 E116 Q 0x11 10 11 Sony SOBAX 2500 Calculator 10 1 J 2 2~ 9 7 2 G 4 4~ B D 5 9 101x 2 1 E212 5 12 3 11 1 1100 2 3 E313 4 12 5 RMØS~ NE16 NA20 1 DM=M1 1 PFCE~ 3 PM.2~ 4 PM.4~ 4 E301 SM.4 8 RP 9 P1D 8 ØD0 7 ØB0 PM.2~ C401 7 (P13+17)~ RD P0F RA PNEWN CJHOME PDPE 11 12 B402 Nb36 Ne27 3 EXEC~ MSETMAN~ OVF~ E302 11 5 3 12 3 TE4 1 11 2 1 2 C402 3 12 11 E301 Ne36 Nc35 4 10 C401 8 3 11 12 ØB 12 7 5 J E101 Q TE1 7 8 C402 2 G Ø K ØB Q~ 10 1 6 J E101 Q TE2 8 4 11 G Ø K ØB Q~ 3 12 7 J E102 Q TE3 5 9 2 G Ø K ØB Q~ 10 1 6 J E102 Q 4 Ne29 Nc32 G Ø K DN TE5 Q~ DN~ 3 7 6 KN.W 11 1 12 E202 2 3 7,8 E202 6 9 KSCS~ CE1 68n KN.4 DE1 8 9 E201 10 6 8 10 E201 7 5 1 11 E201 3 12 10 KN.1 Sony SOBAX 2500 Calculator Rendition: Jun 22, 2025 9 4 2 KN.2 Section: Digit N Page: 19 5 9 9 RACOMP 1 4 P1D 2 ØD15~ SNML~ 6 11 C401 P13+17 2 E301 12 PNCEXT PFSR~ 2 ØD0 1 6 RD 1 9 SNML P09~ 12 PNEDNE 5 5 11 SM.4~ 10 E303 2 SM.2~ 4 E202 5 E302 6 DN=0~ PM.10 (PFMC+RV)~ 11 4 x10 C114 2 5 PNEWN RA 1 C115 3 12 11 9 12 PNEWN~ RB Px2+x3+x6+x7 F.1~ F.2~ F.4 RS P02+03 ((P02+03)•MCI)~ RT KTREAD RT 1 C216 7 3 8 2 C114 6 PM.1 PM.2~ 3 PM.4 4 Px2+x3+x6+x7 PM.4~ P0F ØD0 ØB0 P0F~ P16~ 10 PNEG~ RA 4 C416 7 8 9 C415 (P14+15)~ 5 9 6 8 7 PM.4 RACOMP C416 ØD15~ RA 6 PM.1 PM.2~ PM.8~ RACOMP 7 RDNEG RD~ 8 10 4 C414 9 5 C413 P14+15 6 RDCOMP 4 10 C413 5 Sony SOBAX 2500 Calculator Section: Digit X Gating Page: 20 Rendition: Jun 22, 2025 PM.1~ RNDØ RB 9 7 C111 11 D101 PM.10~ ND34 RD 5 1 4 C115 x10 NE32 12 9 8 7 1 6 PM.8 NC33 2 P0D 5 PM.4~ PM.10 E415 PFRECALL~ 6 RDCOMP 10 4 E415 Px2+x3+x6+x7 5 2 C111 (PFMC+RV)~ 11 4 10 C111 11 12 C110 4 RDCOMP 3 1 C211 2 10 9 C211 6 1 P1C~ 2 3 11 C215 C410 5 (PFSR~•SST•x)~ ØD15 5 DY 4 P08+0C 12 PPH2~ 8 ØD15 9 10 C215 4 x10 ØD15 DY 6 8 9 7 C210 12 11 4 3 C210 1 NB11 10 7 B312 8 6 DXwa~ ØD15 DM 5 2 NC12 IDLE 6 10 9 KCHECK~ 6 8 7 10 5 11 9 C115 3 2 7 8 5 1 2 7 3 11 12 PM.10~ 12 C114 12 3 PM.1~ 1 (P13+17)~ 8 Nc4 9 8 E310 7 Ne1 6 Nb3 DXwb~ A.W 1,11 2,12 DXwa~ B215 TB43 B115 5 J Q 4 2 G 1 TB44 Ø 6 K Q~ 3 3 ØB 4 10 DXwb~ 8 B215 5 11 ØB 12 7 J B116 Q X.1 X.2 A.W A.W X.4 A.W~ A.W~ X.1~ TB45 X.2~ B.W 9 G K A.W~ TB46 Ø Q~ 10 B.W~ X.4~ DXpW 11 12 1 B111 3 2 4 10 B111 5 2 11 12 B211 3 1 B.W DXp4 B.W~ DXp4~ X.4 DXp2 TB34 X.4~ DXp2~ 3 X.2 DXp1 X.2~ DXp1~ 9 8 7 B111 12 6 11 B112 2 DXpW~ ØB0 1 B112 4 B112 x10 9 A.W 8 7 B.W 11 4 B215 6 10 B212 9 5 B213 8,9 x7 6 B112 9 12 8 1 B216 B.W~ 7 8 11 A.W~ 3 7 2 6 ØB B212 8 11 12 7 6 J B115 Q G 10 9 4 B214 Q~ 5 5 2 1 TB41 Ø K TB42 ØB 2 11 B213 10 12 3 1 6 J B114 Q P0D ØD0 ØB0 P14+15 8 7 X.4~ 9 C414 NC14 6 7 NB13 8 B216 6 12 5 11 PM.1~ 2 3 KRDWN~ 4 B312 INTØ~ 5 1 RNDØ A.W~ ØB 4 10 B216 5 1 6 B116 J Q 4 G ØB0 Ø A.W K 2 DY.W B.W~ Q~ 3 B.W TB47 ØB0 3 2 12 11 B313 DXCA~ 5 NB23 NC24 1 NB14 4 KR54~ DY=0~ P08+0C ØD15 11 12 1 B310 3 2 Sony SOBAX 2500 Calculator Section: Digit X Page: 21 Rendition: Jun 22, 2025 DXCA 1 3 11 12 G K Q~ 1 11 11 7 TB40 Ø 8 3 8 3 9 7 B112 9 6 8 B113 6 3 J B114 Q NB17 NC18 9 NE18 TB32 Q~ DX ND17 G 12 ØB Ø 4 7 B113 K 5 x10 10 X.2 X.1 X.2~ X.1~ X.2 X.1~ X.2~ 2 12 B214 2 B113 4 X.1 12 2 B212 1 TB38 X.4 9 5 DXpW 9 8 7 B211 6 10 4 B211 NB9 NC10 5 7 8 9 B313 10 6 XOVF 1 4 2 PM.1~ PM.2 ØD15 ØB0 P0D DXCA 3 C205 11 7 8 C205 9 7 7 P1E 2 C106 1 8 P1E ØD15 C104 PPH2 RB 10 4 C104 4 x10 DYINC G Ø TC9 K Q~ J C101 Q 3 TC1 C204 6 4 C201 8 5 ØB 11 12 7 10 C203 9 2 G 11 Ø K 5 Q~ 12 C203 10 1 12,H2 x1,x11 C204 5 3 ØB 3 2 1 6 J C101 Q TC2 11 G Ø K TC4 Q~ ØB 3 12 C206 5 5 Ø K ØB Q~ 10 2 3 4 8 4~ 1 * 8 3 1 6 TC7 DY 4 G Ø K TC6 Q~ 3 8~ 1~ 1 3 11 11 1 2 C201 3 12 NC13 ND14 Sony SOBAX 2500 Calculator Rendition: Jun 22, 2025 DY=9~ 9 8 7 C106 Nc13 6 Nc36 Nb35 Nc38 Nb38 KDP~ Section: Digit Y Page: 22 1 C102 Q TC5 2 C202 ØB0 C105 2 G J 1 PM.1~ 2 12 5 9 12 8~ 1 * 7 C102 Q 2~ 2 4 2 C105 12 J 4~ 4 1 3 11 8 4 2~ 2 12 C104 9 TC10 4 1~ 11 5 8 6 C103 Q 8~ 8 4 4 10 C105 1 J 6 11 3 TC14 RB 7 TC3 9 ØD15~ PNCEXT 6 7 P13+17 PM.4~ PM.8 9 C206 RB (P13+17)~ 2 PM.10~ PM.2~ 6 8 ØD15~ 12 C105 10 PM.4 11 5 6 8 ØD15~ P16~ 9 C201 ØB P11+16 RDCOMP 8 6 9 ØB0 PM.2~ 7 10 ØD15 RACOMP 5 12 DY=0~ µY: PDPE, DY.W PDPE~ P1E ØD15~ RA P0F DN PM.2 PM.10 KCA~ 4 10 C406 5 PM.4~ RA P1E~ P0F~ 10 4 PM.4~ C112 5 DX P1E ØD15~ RB P1E ØD15 RA KCA~ (Px2+x3+x6+x7)~ PM.4~ RB P1E~ PNCEXT DY 9 PPHE~ 8 PPH2~ CJHOME~ PQRDØ~ 7 10 4 C404 P1D C404 6 don’t shift RB 5 P1E~ 10 PM.1 4 C113 7 8 9 PM.10~ C212 F.8~ 6 ØS0 9 8 7 RT C112 6 TC34 NC25 NF30 10 1 4 C212 5 KTON 4 10 P02+03 RAw E413 5 ØS0 11 RT 12 C212 3 2 ((P02+03)•MCI)~ 2 ØS5 12 DX 1 C112 1 2 12 E415 3 11 11 12 1 E414 NE33 NF34 NE39 NF40 Ne7 NF27 3 RTw~ 2 2 11 1 E413 3 12 3 11 7 8 9 C213 6 11 P02+03 2 12 C213 F.1~ 3 1 DX 2 SPARM 11 1 C214 ØB3 3 12 SM.1 8 9 7 SM.2 C214 10 4 7 9 8 SØDATPC 6 C113 C213 NC31 NF31 5 RBw SPARM~ 12 11 2 E409 1 3 10 x4 E410 F.1~ DN~ 9 8 E409 11 6 7 9 8 E410 6 2 10 11 12 E411 12 5 7 4 E411 3 5 RSw 1 2 E410 3 1 ((P02+03)•MCI)~ 10 4 E409 5 RSwENB 6 11 12 PM.4 shift up 1 C113 5 2 DY SM.2~ 3 SM.4 SØDATPC RS Sony SOBAX 2500 Calculator Section: Registers A, B, T & S Gating Page: 23 Rendition: Jun 22, 2025 11 12 2 E308 1 RE1 1K 3 4 10 E308 RE4 1K 5 RP P18 PDPE~ 7 9 9 10 8 INTØ B405 PDPE 6 INTØ Nb15 4 CJHOME 10 B405 Ne13 INTØ~ 5 CJHOME~ RD P08+0C PM.4~ PNEWN~ PDPE UNITØD ØB3 11 1 B405 PNEWN RD 9 8 7 PM.4~ 11 1 4 B406 P0F~ PFCE~ PM.4~ (Px0+x1)~ P0A~ PM.4~ ØD15~ ØB3 RDD=0 7 P1C~ 9 C207 8 10 (KCHECK•S6)~ 4 C207 5 6 RD 10 PFCE~ 9 PM.1~ 8 C107 6 RD 1 11 C415 3 10 x4 P11+16 C415 RB3 1K 2 3 clear RD on 1st nml Nb13 NF39 12 11 C209 5 10 x4 F411 5 RDw Nc14 1 9 10 C109 5 CJHOME~ 12 PQPA~ 6 8 1 11 2 C207 3 12 4 unblanking 2 12 11 C107 7 2 5 12 7 6 DN PM.1 <1 units 0 3 2 C110 P1C~ PM.2~ 3 12 4 (Px2+x3+x6+x7)~ 6 8 2 PNEDNE Nc16 7 B406 5 3 1 11 blanking 0b1000 12 3 4 C109 5 2 1 OVF PM.1~ (KCHECK•S6)~ 4 x10 C106 SNML DN SNML~ Section: Register D Gating Page: 24 CJHOME ØB03 P0F Rendition: Jun 22, 2025 9 7 C108 10 5 ØD0 Sony SOBAX 2500 Calculator 8 DX 7 8 C209 6 LIST-mode numeral 6 9 1 12 2 C108 LIST-mode function 3 f17 11 ØB~ 4 10 C108 5 10 x4 F311 Traces on board but F311 absent. F311 QF30.B 6 7 9 5 8 910 5 PWROFFP 4 Acoustic Delay Line ADL Injection Pulse Monostable 820 TF36 30p 7.5K 820 TF38 82p 30p QF21, *22 C641 5.6K *6.2K QF26, *27 C641 QF27, *24 C641 4.7K *4.3K ØS CF27 91p F304 Tf6 5 ØS14 2 1 6 11 ØS 12 7 J F404 Q 1µ 16V 8 9 2.4K 39K 2n2 20K Tf1 220 QF4 C403A 68 510 3 390p 2.2K 1µ 25V 1.5K 1µ 16V 47µ 16V TF11 QF2 C403A 15K 510 270 3.3K 2n2 Tf2 30K 11K 2.4K 2n2 8.2 K 3K 560 *510 QF30,*31 C641 C403A 51K 75 NF36 NE35 Ø RTw~ K Q~ J F404 Q 3 ØS2 Nf28 8 9 G ØS1 Ø K ØS Nf24 Nf25 Q~ ØS 11 12 7 10 5 ØS 2 1 6 8 ØS3 ØS 11 12 7 3 4 5 E314 RT G ØS2 7 22n 4 DLb 6 1 C403A 7 QF5 C403A 2.7K 1.5K QF7 C641 TF6 100 2n2 220 2n2 ADLINJ 1 5 2 8.2K 10µ 16V ADL Pulse Amplification & Reforming 8 RPØS~ rd gn 68n 3.3K 1K ØS RMØS~ Tf8 1.2K 5.6K *6.2K 8,9,10 11,12 560 510* 820 10µ 16V NE27 NF28 2 2 ØS 1 6 8 11 ØS 12 7 J F405 Q NF21 NC17 9 ND18 G Ø 7 9 F410 6 9 Q~ J F405 Q 1K ØS3 10 F412 NF35 4 Ø J F406 Q Nb5 RD Nc6 8 5 ØS4 NF33 9 Nb6 RB Nc3 F406 Q 1 11 F411 3 ADL Bit Recovery Flip-flop 8 RBw ØS5 Nf16 J 12 Nf1 3 Ø Q~ TF44 1 12 G K F310 2 RDw NkD Nf18 Q~ 11 10 G K 10 4 RAw ADLRD 8 Nf26 K 7 9 6 R 1.5K NF38 ND35 Ø QF3 C641 ØS 2.2K 4 RS NE37 91p 820 F411 10 G 820 TF10 4 RSw 10 F410 DLRCV 5 Q~ J F407 Q 5 2 G Ø ØS Q~ 10 RSc 1 6 J F407 Q Nf7 G ØB~ Ø K Nf21 Q~ 20p 20p 5.6K RSd 91p S 820 TF9 5.6K QF6 C641 12 11 F410 3 1 3 8 ØS Section: Registers A,B,D,T,S Page: 25 Rendition: Jun 22, 2025 1K 2 4 RSwENB Sony SOBAX 2500 Calculator 4.7K 1K QF8 C641 3 9 4.7K Q Nf23 K K RA RTw Nf6 F408 5 J Q 4 2 G ØS1 1 Ø 6 K Q~ 3 11 12 7 F409 J Q 5 9 G Ø K ØS Q~ 10 2 1 6 F409 J Q Nf2 4 ØB0 G ØS2 Ø K INIT~ Nf4 Q~ 3 ØD0 ØB0 ØS2 1 8 2 11 F412 11 3 12 9 7 8 F412 6 ØS 12 7 J DLa F302 Q Nf42 5 9 2 G Ø K Nf40 Q~ 10 ØS 1 6 J DLap F302 Q Nf36 4 INIT~ G Ø K Nf34 Q~ 3 8 9 7 F303 6 2 12 11 F303 1 3 V+130 12K 1W W 4~ 1~ W~ 2~ 1 W~ 2 1~ W~ 2 1 W~ 4 W 4~ 2 DXpW ØB3 ØB DXpW~ DXp4 ØB3 ØB DXp4~ DXp2 ØB3 ØB DXp2~ DXp1 ØB3 ØB DXp1~ 5 2 1 6 8 11 12 7 5 2 1 6 B315 J Q W 4 W G Ø K J 4 2~ 1~ Q~ B315 Q 3 W~ 4 2~ 9 4 1 G Ø K J 4 Q~ B314 Q 10 4 4~ 2 1~ 2 4 G 2 Ø 1 K Q~ 3 B314 8 J Q 9 11 G 12 Ø 7 K Q~ 10 2~ W~ 4~ 1 2~ 1~ W 1~ 4~ 2~ 1 IDLE 7 9 8 7 8 ØD0~ B415 9 12• NB26 NA25 3.9K B416 27K 1W 12• C926 10• 75K 6 6 9 7 8 B414 10 x4 6 B415 V+130 NB28 NA27 5 510 C926 12 1 11 B414 4 x10 3 B414 6• 33K NB30 NA29 5 2 1 11 B413 3 4 10 B413 6 7,8 9 B412 3 4 10 B412 2 6• 1µ 160V NB32 NA31 5 3 4 5 6 7 6• 750K 12 7 8 9 B413 NB34 NA33 6 12 2 11 B412 NB36 NA35 INIT~ 5 1 V+200 2 12 11 B411 3 4 x10 6 4 x10 B411 DIGIT 1 (LSD) DIGITS 2 to 15 NB38 NA37 5 C926 4.3K ?W 1 100K 9 8 7 B411 B410 NB40 NA39 5 2.2K ØD1 1 2 NB42 NA38 11 B410 10 x4 3 A111 Hitachi 0 2 4 6 8 . 1M CD81 1 3 5 7 9 5 J 12 8 9 7 B410 9,8 x7 6 1 DP 12 INTØ 11 B416 B310 NB12 V+130 NA15 3 10 x4 B416 NB16 NA16 Rendition: Jun 22, 2025 Fct J mult ÷ + R √ – Mout = D Mc M Min S 3.9K V+130 51K 1M 5 12 Sony SOBAX 2500 Calculator V+130 51K KCHECK~ 2 1 B415 300K Digit Lamp 1 2 3 4 5 6 7 8 9 10 11 12 13 14 DB8 3 2 11 NB44 NA43 6 RDNEG Section: Display Page: 26 1M 2K ØD0 2 1M 8 C926 nOVF 9 7 3.9K A111 6 C926 51K OVERFLOW 3.9K SPEXP 1M C926 Pexp 510 SP1ST P1st C634 DM=M1 B136 1K 1 rd C867 200 VAC 10µ 450V 10K ?W rd 1µ 350V 47K ?W C634 1.5K 3K 1W 47n C634 C634 6.2K VR2 2K 150K 200K V+200 NA2 C756 V+200 5µ 150V NA1 V+130 24K 51K ?W 200K LA bu F2 3.15A 8 VAC F1 0.8A 117VAC 32W POWER 22m 16V POWER 2SD88A +4V 220µ 6.3V 2K bu og 100µ 16V 100µ 25V 150n NA7,8 NB3,4,b43 2SD28 2K C634 VR1 1K NC3,4,c43 7.5K ND3,4,d43 2.4K 1µ 50V 2n2 NA3,4 wh NE3,4,e43 NF3,4,7 NKA,B,C 47µ 10V 47µ 10V 13 47µ 10V all ICs 47µ 10V 14 47µ 10V 3• 47µ 16V 68n NA5,6 NB1,2,b43 NC1,2,c43 ND1,2,d43 bn 15 VAC bn F3 0.35A NE1,2,e43 2SD28 1m 25V 2K 4.3K 10µ 16V UNUSED GATES NF1,2,11,13 10µ 16V 47µ 16V NKP,R NF9 68n 4 68n V–10 10 B213 C103.4 5 4 10 C202 5 4 10 C403 5 7 8 9 D413 6 1 Sony SOBAX 2500 Calculator Section: Power Supply & Unused Gates Page: 27 Rendition: Jun 22, 2025 2 11 E416 12 3