Cypher-Plugboard Board - 64-Character Variant Design Specification

Status: Draft Project: Enigma-NG Version: v.0.1.0 Associated Hardware Revision: Rev A Last Updated: 2026-08-19 Parent Document: design/Electronics/Cypher-Plugboard/Design_Spec.md

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1. Overview

This document specifies the 64-Character variant of the Enigma-NG Cypher-Plugboard Board. It supports the full extended cipher alphabet - A-Za-z0-9+/ (26 uppercase letters + 26 lowercase letters + 10 digits + 2 base64-extra symbols), mirroring Cypher-Input's/Cypher-Output's own 64-Character variant character set.

All three Cypher-Plugboard variants share an identical electrical circuit (connector-only HID / USM mating) and an identical PCB strip (J1/J2 only - see design/Electronics/Cypher-Plugboard/Design_Spec.md). Only the jack field's row count, character layout, and jack quantity differ between variants; since the jack field mounts to a separate machined metal enclosure (not the PCB), this is the variant with the tallest enclosure of the three (see parent Design_Spec.md §1/§4).

2. Jack Field Layout

64 plug positions, each with 2 jack sockets (Pass 1, Pass 2) placed immediately next to each other, horizontally. Arranged in 7 rows, top-to-bottom:

Row	Characters	Positions	Notes
1	0 1 2 3 4 5 6 7 8 9	10	Digits, left-to-right
2	A B C D E F G H I	9	Uppercase, first block
3	J K L M N O P Q R	9	Uppercase, second block
4	S T U V W X Y Z +	9	Uppercase, third block (8 letters) + + appended so all 3 uppercase rows are evenly 9 wide
5	a b c d e f g h i	9	Lowercase, first block
6	j k l m n o p q r	9	Lowercase, second block
7	s t u v w x y z /	9	Lowercase, third block (8 letters) + / appended so all 3 lowercase rows are evenly 9 wide

Total: 64 positions, 128 jack sockets. Row 1 (digits) is the widest row at 10 positions; rows 2-7 are evenly 9 positions each, giving a visually symmetrical panel (per user direction, 2026-08-18) rather than an uneven 9/9/8 split - + and / are appended to the last uppercase and last lowercase row respectively to even them out.

Character order: within each row, characters run in plain alphabetical/numeric order, left-to-right (not a QWERTY-style layout like Cypher-Input's own key arrangement) - the Plugboard is a technician-facing patch panel, not a keyboard.

3. RefDes Allocation

Jacks are numbered sequentially, row by row (top-to-bottom), left-to-right within each row, with the Pass 1 jack immediately followed by its Pass 2 partner at each position:

Row	Characters	RefDes Range	Qty
1	0-9	J3-J22	20
2	A-I	J23-J40	18
3	J-R	J41-J58	18
4	S-Z, +	J59-J76	18
5	a-i	J77-J94	18
6	j-r	J95-J112	18
7	s-z, /	J113-J130	18

Total: J3-J130, 128 jack sockets.

4. Bill of Materials

RefDes	Specification	MPN	Manufacturer	DigiKey PN	Mouser PN	JLCPCB PN	Alt Supplier + PN	Notes	Footprint Available	Footprint Downloaded	Qty
J3-J130	Switchcraft 12A ("E12A"), 6.35mm (1/4") 2-conductor switched panel-mount jack	12A	Switchcraft	SC1089-ND	502-12A	-	-	Plugboard patch jacks, 64 positions x 2 passes; manually assembled, not part of the JLCPCB PCBA order (no JLCPCB PN); 3/8-32 UNEF-2A threaded bushing	-	-	128

Sourcing status: confirmed 2026-08-19 - Switchcraft 12A, DigiKey SC1089-ND, Mouser 502-12A. Datasheet: design/Datasheets/Switchcraft-12A-datasheet.pdf.