
Toyo |
Toyo Specialized Business Development Co.
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![]() P120 Toyo w/ Bamboo Cursor | Toyo w/ Bamboo Cursor- c1940-1945 Made in Japan - Manufacturer Presumed to be Relay Front Scale A, [ B, CI, C ] D Back Slider: [ S, L, T ] Archive - no longer in collection Someone in Japan, Prior to, or during WWII provided this with a bamboo cursor frame. It was given to a young American business woman, now a grand mother, as a gift by a Japanese visitor, prior to WWII. The company name is in the insert. At first I thought this was a one-of-a-kind, possibly a homemade cursor frame, but another showed up as being in Ed Chamberlain's collection, when he put it on eBay (sold for $100). My conclusion is that due to a shortage of steel the company (Toyo) that handed out these slide rules as a promotional item, made these useful with the bamboo frame. This specimens has the 'equivalents' sheet on the back.
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![]() S316 Relay 150 | S316 Relay 150 - c1940-1945 Made in Japan - Pre-1945 Relay - missing cursor Front Scale (extended) 25cm // K, A, [ B, CI, C ] D, L || 10in Back Scale: [ S, S&T, T ] Equivalents
I found this one that looks like the same
company name (see insert) as my P120 above. This tells me that both slide rules must be made by Relay
since the Japanese companies were very brand loyal and the distributor would not have used multiple competing suppliers.
I assume that this one also had a bamboo framed cursor but it failed to
survive the war. |
![]() P266 Alco Personal Calculator | Alco Personal Calculator Made in Japan - Aluminum Addiator and Slide Rule Front Scale Mechanical Addiator (+ / -) Back: A [ B, CI, C ] D |
![]() P236 Delta - Ozi SeisaKusho | Delta - Ozi SeisaKusho Made in Japan - Aluminum with stainless rod as used to retain slide Front Scale DF [ CF, CI, C ] D Back: Blank ![]() |
![]() P099 Engineers No.5500 | Engineers No.5500 - Open Duplex Made in Japan - code KK-4 Front Scale A, [ B, S, T, C ] D, K Back Scale DF [ CF, CI, C ] D, L |

![]() S246 Fuji F-100 |
Fuji F-100 Made in Japan - 7 scales Front Scale DF [ CF, CIF, CI, C ] D, A Back: Blank Original Owner: NIB/Netherlands |
![]() S192 Fuji 129 Student Log |
Fuji 129 Student Log Made in Japan - 14 scales Front Scale L, K, A [ B, CI, C ] D, S, ST, T Back Scale 25cm [ S, LL-1, LL-2, LL-3 ] 10inch |
![]() S253 Fuji 129-01 Student Log |
Fuji 129-01 Student Log Made in Japan - Note: The bridges were put on the opposite side Front Scale L, K, A [ B, CI, C ] D, S, ST, T Back Scale 25cm [ S, LL-1, LL-2, LL-3 ] 10inch Original Owner: NIB/Netherlands |
![]() P156 Fuji 505 Rietz |
Fuji 505 Rietz Made in Japan - 7 scales Front Scale 13cm // K, A [ B, CI, C ] D, L Back Slider [ S, ST, T ] |
![]() P157 Fuji 535s |
Fuji 535s Made in Japan - 8 scales Front Scale 13cm // A [ B, CI, C ] D, K \\ 5in Back Slider [ S, L, T ] |
![]() P052 Fuji 552P Duplex Log/Log |
Fuji 552P Duplex Log/Log Made in Japan - 23 scales Front Scale LL-0, K, A [ B, T, S, C ] D, P, L, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 |
![]() REF Fuji 553P Duplex Log/Log |
Fuji 552P Duplex Log/Log Made in Japan - 23 scales Front Scale T1, T2, DF [ CF, CIF, CI, C ] D, P, S Cos, ST Tan Back Scale LL-1, LL-2, LL-3, A [ B, L, K, C ] D, LL3, LL2, LL1 Multiple Hairlines Archive - Scan provided by Koen Schram, Netherlands |
![]() S216 Hope 65-G |
Hope 65-G - Closed simplex Made in Japan by Hope Slide Rule Mfg. Co., Ltd. Front Scale LL3, LL2, LL1, A [ B, BI, CI, C ] D, DI, K, LL0 Back Slider [ T1, T2, L, S ] Back: blank |
![]() P147 Hope - Modine Pocket | Hope - Modine Pocket Made in Japan, by Hope Slide Rule Mfg. Co., Ltd. Front Scale 13cm // A, [ B, CI, C ] D, K \\ 5in Back Slider: [ S, L, T ] Back adv: Modine |
![]() P127 Kutsuwa FN-401 | Kutsuwa FN-401 Made in Japan - Retail Package Front Scale A, [ B, CI, C ] D, K Back Slider: [ S, L, T ] |

![]() S025 Lafayette F-381 |
Lafayette F-381 - Closed simplex OEM Japan for U.S. company Radio Shack Front Scale A [ B, CI, C ] D, K Back Slider [ S, L, T ] Back: Conversion Chart |
![]() C32 Lafayette F-382 (Concise 270) |
Lafayette F-382 (Concise 270) Made in Japan by Concise - 11.2cm Dia Front Scale L, D ( C, CI, A, K ) Back Scale DI, D ( S, T1, T2, ST ) |
![]() P162 Lafayette F-681 Decilog |
Lafayette F-681 Duplex Decilog dc J.K-1 1961 OEM Japan Ricoh for U.S. Company Lafayette - 24 scales Front Scale LL-0, L, K, A [ B, S, T, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 |
![]() P220 Lafayette 99-7030 |
Lafayette 99-7030 OEM Japan Relay/Ricoh for U.S. Company Lafayette - 9 scales Front Scale A [ B, CI, C ] D, K Back Scale: [ S, L, T ] Back: Quick Computing aids |
![]() P179 Lafayette 99-7099 Decimalog |
Lafayette 99-7099 Decima-log 1961 OEM Japan Relay/Ricoh for U.S. Company Lafayette - 24 scales Front Scale LL-0, L, K, A [ B, S, T, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 |
![]() P180 Lafayette 99-7099 Decima-log |
Lafayette 99-7099 Decima-log 1961 OEM Japan Relay/Ricoh for U.S. Company Lafayette - 24 scales Front Scale LL-0, L, K, A [ B, S, T, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 |
![]() GFT Lafayette 99-70559 Decima-log |
Lafayette 99-70559 Decima-log dc Q.S-3 1968 OEM Japan Relay/Ricoh (QS-3) for U.S. Company Lafayette - 28 scales Front Scale LL-0, L, K, A [ B, S Cos, ST ST, T Cot, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 Donation of Russell Fox, Anchorage, Alaska. |
![]() REF Lafayette 99-7128 Decimadyne |
Lafayette 99-7128 Decimadyne OEM Japan Relay/Ricoh for U.S. Company Lafayette - 24 scales Front Scale db -20-0 +0-20, DF [ CF, CIF, CI, C ] D, A Back Scale XC, XL, K [K1, S, T ] F2, F1, DI, Archive - David Hecht collection |
![]() S188 Lutz 102SC |
Lutz 102SC - Duplex Made in Japan Front Scale S, K, A [ B, CI, C ] D, L, T Back: Blank |
![]() S094 Lutz 252 USGovt |
Lutz 252 US Govt - Duplex Made in Japan - Marked as U.S. Government Front Scale K, A [ B, T1, T2, ST, S] D, DI Back Scale DF [ CF, CIF, CI, C ] D, L Back: Conversion Chart |
![]() S306 Micronta 150 Duplex Decitrig Log/Log |
Micronta 150 Duplex Decitrig Log/Log Made in Japan by Relay/Ricoh J.K-3- 21 scales Front Scale LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 |
![]() P161_Micronta_505 | Micronta_505 Made in Japan (HK-1) Front Scale 13cm || A, [ B, CI, C ] D, K || 5in Back Scale: [ S, L, T ] Back: Equivalents Help! Need a Cursor, can use Ricoh/Relay 505/501 |
![]() P054 Micronta 551 Duplex Log/Log |
Micronta 551 Duplex Log/Log Made in Japan - 24 scales Front Scale LL-0, L, K, A [ B, T, S, C ] D, DI, P, LL0 Back Scale LL-1, LL-2, LL-3, DF [ CF, CIF, CI, C ] D, LL3, LL2, LL1 |
![]() S380 Olson TL-373 (Relay 150) |
Olson TL-373 (Relay 150) Made in Japan by Relay/Ricoh for Olson (electronic supply), Akron, Ohio. Front Scale LL0, LL00, A [ B, K, CI, C ] D, S, ST, T Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 |
![]() S019 Omega DT-1015 |
Omega DT-1015 Duplex Made in Japan by Relay/Ricoh for Omega Front Scale K, A [ B, S, ST, T, C ] D, D1 Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL2, LL3 |
![]() S026 Relay 82 |
Relay 82 - Closed simplex Made in Japan Front Scale A [ B, CI, C ] D, K Back Slider [ S, L, T ] Back: Blank |
![]() S027 Relay 83 |
Relay 83 - Closed simplex Made in Japan Front Scale K, DF [ CF, CI, C ] D, A Back Slider [ S, L, T ] Back: blank |
![]() S171 Relay 102 |
Relay 102 - Closed simplex Made in Japan by Keikico Front Scale A [ B, CI, C ] D, K Back Slider [ S, L, T ] Back: Conversion Chart |
REF Relay 157 (Electrical) |
Relay 157 - (Electrical) Duplex Made in Japan by Keikico (Ricoh) Front Scale Sr, SΘ, P', P [ Q, CF, CI, C ] D, DF, LL2, LL3 Back Scale Sh2, Sh1, A [ B, K, Th, C ] D, Tr1, Tr2, db Archive - Atsushi Tomozawa collection (Japan) |
REF Relay 158 (Electrical) |
Relay 158 - (Electrical) Duplex Made in Japan by Keikico (Ricoh) Front Scale Sh2, Sh1, Th, A [ BI, S, T, CI, C ] D, LL3, LL2, LL1 Back Scale X2, X1, P2, P1 [ Q, Y, L, LX, I ] I, LΘ1, LΘ2, LY Archive - Atsushi Tomozawa collection (Japan) |
![]() P134 Relay T-501 | Relay T-501 - Closed simplex Made in Japan Front Scale 13cm // A, [ B, CI, C ] D, K || 5in Back Slider [ S1, L, T1 ] Back: Conversion Chart |
![]() P135 Relay 505 | Relay 505 - Closed simplex Made in Japan Front Scale 13cm // A, [ B, CI, C ] D, K || 5in Back Slider [ S, L, T ] Back: Conversion Chart |
![]() REF Relay 605 Electro | Relay 605 Electro Made in Japan Front Scale 15cm // Dynamo-Mot, L1, A [ B, CI, C ] D, L2, Volts || 6in Back Scale: [ S, L, T ] Back: Equivalents Table Archive - Atsushi Tomozawa collection (Japan) |
![]() S091 Ricoh 107 Electro |
Ricoh 107 Electro - Closed simplex Made in Japan Front Scale E (Dynamo), V (volt), A (amp)[ B, K, CI, C ] D, S, T Back Slider [ LL3, LL2, LL1, L] Back: Conversion Chart |
![]() S333 Ricoh 150 Duplex Decitrig Log/Log |
Ricoh 150 Duplex Decitrig Log/Log Made in Japan by Relay/Ricoh RS-3, 21 scales Front Scale LL0, LL00, A [ B, K, CI, C ] D, S Cos, S T, T Cot Back Scale L, LL1, DF [ CF, CIF, CI, C ] D, LL3, LL2 |
![]() P082 Ricoh 403 4inch | Ricoh 403 - Closed simplex Made in Japan - in Retail Box Front Scale 10cm // A, [ B, CI, C ] D, S, T Back Slider [ S, L, T] Back: Conversion Chart |
![]() P105 Ricoh 550 | Ricoh 550 - Open Duplex Made in Japan by Relay - code NK-2 Front Scale A, [ B, S, T, C ] D, K Back Scale DF [ CF, CI, C ] D, L |
![]() S104 Japanese Unknown |
Japanese Unknown - Simplex Made in Japan Front Scale S, K, A [ B, CI, C ] D, L, T Back: Blank |