This collection bundles the following memos dedicated to the so called exact base-21 (EBTO) and quasi base-21 (QBTO) serial transport codes: [1] "Base-21 Scrambling" (discusses about EBTO codes, present at pp. 1-4 in the bundle); [2] "Base-21 Word Alignment and Boundary Detection" (EBTO, pp. 5-8); [3] "Quasi Base-21 Words" (QBTO, pp. 9-12); [4] "Quasi Base-21 Words Generated Compactly" (QBTO, pp. 13-16); and [5] "Quasi Base-21 Words Balanced on the Framework" (QBTO, pp. 17-20).