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Micro Switch SD Series keyboards

This page documents a portion of the known Micro Switch SD Series Hall effect keyboards.

Contents

Schema

The model number schema for SD Series keyboards is as follows:

KSDA-(L-)B(-C)

K
Number of keys
“SD”
Series name
A
Unknown; numeric
L
Locale
B
Unknown; numeric
C
Unknown; alphabetic

Position A conceivably indicates the subseries, and position B appears to denote the index within that subseries. The exact scope of each subseries is not clear, as some characteristics are not consistent between examples. Documented examples are shown in the table below. Exceptions to what was given in Micro Switch’s advertisements are annotated with the catalogue listing of the deviation. Possibly the subseries code relates more to the circuit logic than it does the other characteristics.

Subseries Input Termination Output
SD1 +5 V DC Card edge BCD
Six-bit address
SD3 +5 V DC Solder pad
40-pin header 		Wired-only (level)
SD5 +5 V DC, −12 V DC Card edge US ASCII
SD6 +5 V DC, −12 V DC Card edge EBCDIC
SD12 +5 V DC, −12 V DC Card edge
Vertical IDC socket (125SD12-1)
Horizontal IDC socket (59SD12-5) 		Six-bit address
EBCDIC
SD17 +5 V DC Solder pad
SIL socket (63SD17-3-B) 		Wired-only (scan)
SD24 +5 V DC Right-angle header US ASCII
SD30 +5 V DC Right-angle header US ASCII

Note that EBCDIC is an 8-bit character set, which makes SD12 curious considering that its two documented outputs are EBCDIC and six-bit address. There are also various examples where the connector does not match the official information. These inconsistencies presently prevent any certainty as to what these subseries actually represent. Note also that the term “right-angled header” indicates an IDC socket with the cable exiting parallel to the PCB. Examples of SD30 boards appear to show both locking socket and non-locking sockets.

The additional locale position (L) is only known from the Burroughs TD730/TD830 keyboards:

Catalogue types

Catalogue listing Application Power requirement Termination Output Modes Keytops Catalogue
12SD3-1 High-speed numeric entry +5 V DC, 50 mA Solder pad Wired-only (level) — Standard EEM 1983, 1985
16SD1-1 +5 V DC, 132 mA Card edge BCD 1 EEM 1983, 1985
16SD1-2 EEM 1983, 1985
16SD3-4 +5 V DC, 80 mA Solder pad Wired-only (level) — EEM 1983, 1985
16SD3-5 +5 V DC, 80 mA — Relegendable EEM 1983, 1985
16SD3-6 +5 V DC, 130 mA — Standard/LED EEM 1983, 1985
16SD3-7 +5 V DC, 80 mA — None EEM 1983, 1985
16SD3-12 +5 V DC, 80 mA 40-pin header — Standard EEM 1983, 1985
16SD17-1 Adding machine format +5 V DC, 80 mA Solder pad Wired-only (scan) — Relegendable EEM 1983, 1985
16SD17-2 Telephone format +5 V DC, 80 mA — None EEM 1983, 1985
26SD1-2 Point of sale +5 V DC, 250 mA Card edge Six-bit address 1 Standard/relegendable EEM 1983, 1985
51SD12-4 Typewriter array +5 V DC, 200 mA
−12 V DC, 10 mA		 Card edge Six-bit address 1 Sculptured EEM 1983
53SD5-2 Communications (Model 33 array) +5 V DC, 250 mA
−12 V DC, 50 mA		 Card edge USASCII 4 Sloped EEM 1983
64SD30-1 +5 V DC, 156 mA Right-angle header USASCII 4 Stepped EEM 1983
64SD30-9 EEM 1985
66SD6-6 Interactive Visual Display (IBM 3790) +5 V DC, 500 mA
−12 V DC, 5 mA		 Card edge EBCDIC 2 Stepped EEM 1983, 1985
66SD12-10 EEM 1983, 1985
66SD6-7 Interactive Visual Display (IBM 3270) EEM 1983, 1985
78SD6-5 EEM 1983, 1985
83SD30-2 Interactive Visual Display (DEC VT 100) +5 V DC, 350 mA Right-angle header USASCII 4 Sculptured EEM 1983, 1985
87SD30-8 Interactive Visual Display (IBM 3278) +5 V DC, 300 mA 1 Front stamped/standard EEM 1983, 1985
87SD30-9 EEM 1983, 1985
63SD30-1 General-purpose visual display +5 V DC, 156 mA 4 Stepped EEM 1983, 1985
63SD30-4 EEM 1985
103SD24-2 Intelligent terminals +5 V DC, 500 mA EEM 1983, 1985
103SD30-2 +5 V DC, 125 mA EEM 1983, 1985
104SD30-Series European arrays +5 V DC, 350 mA EEM 1983, 1985
EEM 1983
Electronic Engineers Master 1983–84, Volume 1, pages 2422–23
EEM 1985
Electronic Engineers Master 1985–86, Volume B, pages 1732–33

Discovered types

The examples below are discovered types of interest. This includes models that are especially early or late production, or where all the different switch types are documented. SD Series keyboards have at times what appears to be the highest number of different switch types within the same keyboard. For clarity, the switches below are listed only by their identification codes, rather than the full part numbers (which cannot be proven). See the SD switches page for details on the different switch types.

Keyboard Micro Switch listing Date example Switches Notes
SD Series Engineering Keyboard Prototype 52SD5-1 ca. 1974 “O O” or “0 0”
Univac keyboard 125SD12-1 76/50 1AS, 1DS, 3AS, N3AS, 3BS, 6AS
Unidentified keyboard (alphanumeric block) 68SD15-1-E 7750 1A3A, 1A3B
Integrated numeric keypad from the above 15SD15-1-E 77/38 1A3A
Unidentified keyboard 59SD12-5 77/50 1B3B, 9B3B, …?
Diablo terminal keyboard (repurposed) 75SD12-1 7824 4B3A, 4B3B, 4B1K, 4B3K, 5B3A, 6B1D, 10B3A Uses timed repeat (K) switches for backspace, return, enter, space and [./>], as a means to achieve auto-repeat. It also has a secretarial shift mechanism. Not all the switches are clearly depicted.
Unidentified keyboard 70SD22-4 7835 11B1S, 11B2S, 6A1D, 10B3S This highly unusual model has secretary shift, tactile switches, a locked-out key and an SD Series encoder.
Unidentified keyboard 76SD5-3 7850 4A3A, 4A6A, 5A6A, 12A3A, …?
Diablo terminal keyboard 75SD12-1 7938 T4B3B, 4B1K, 5B3A, 6B1D, 10B3A, …? As with the earlier 75SD12-1 but with T4B3B switches (observed on the number row); not all switches are depicted
Unidentified keyboard 112SD12-2 7950 T4B3B, 4A3B, 10B3A, 10B1A, 6B1D, 4A1B, 6A1D The secretarial shift mechanism uses two 10B3A on the left and one 10B1A on the right, the latter paired with 6B1D. The dummy switches have pale grey shells, and 6A1D has a blue plunger.
Burroughs TP110 ca. 1980 4A1E, R4A3E, 4A8E, 5A3E*, 6A1D
UGC-74 keyboard N/A ca. 1980 1F5A
Sperry/Univac keyboard 70SD30-2 ca. 1980 R4V3E
Texas Instruments Silent 700 Model 745 63SD17-3-B 8052 1A3S, 1A8S, …?
Burroughs TP130 106SD29-17 8101 4A1E, R4A3E, 4A8E, 5A3E, 6A1D
NEC Spinwriter 7720 keyboard 76SDU-3J1612 7-82NT 4B3A, 4B3B, 5B3A, … Manufactured by Yamatake-Honeywell and contains a secretarial shift mechanism; largely the same layout as the Diablo keyboards
Honeywell terminal keyboard 106SD29-17 8238 4B3E, 4B6E, 5B3E, 4B1D, 4N1E
Space-cadet 100SD30-1 8242 4B1E, 4B3E, 5B3E, 6B1D
Bunker Ramo Admin Keybrd (0106343-011) 1982-11-11 2K3S, D1K3S
Wang OEM keyboard N/A ca. 1982 4T2B, 4A2B, 4A2K, 4B2K TTL matrix co-ordinate encoded using pulse switches; unusual in that it uses all 2 oz switches instead of the normal 2.5 oz
Texscan MSI keyboard 112SD34-1 8339 4B3S, 5B3S, 10B3S Customer part number is 09-9103200. The only depicted secretarial shift switch is 10B3S, on the left side.
Telex 952003-222 87SD30-29 8410 4B1D, 4B1E, 4B3E, 6B1D
Unidentified assembly 76SD30-2 8513 4U3E, …? Uses custom switches with cruciform stems; possibly more than one switch type, but not clear
Micro Switch 99SD24-3 99SD24-3 8533 4B3S, 4B1S, 5B3S, 6A1D, 6B1D, 10B3S, 1F3S
Wang 271-1247 N/A 1987 4A2B, 4T2B, …?
Micro Switch 26SD1-2-H 26SD1-2-H 9023 4A1A, 4A3A, 6A1D This design dates back at least as far as December 1973, when it was depicted uncaptioned in a Micro Switch keyboards advertisement in Electronic Design magazine
Bud Keypad 83959 16SD3-12-H 9042 4A3A
Sun 32SD38-4-E 32SD38-4-E 9618 16B3E
Unidentified keyboard 142SD10-3-H 990? 11B1A, 4B1D, …? First discovered tactile type; the date code and model number are unreadable, but various websites report that “142SD10-3-H” exists, with no results for “142SD18-3-H”

* Switch visible, but part number cannot be confirmed

Documentation

The following advertisments and articles were scanned by Bitsavers unless otherwise noted.