The "standard abacus" used today, with 35 columns of five rhomboid beads, one above and four below, is in fact an improved model invented by the Japanese called the "chao ho" abacus. There was also an earlier model, which had one bead above and five below, known as the "ta cheng" abacus.
然而，今天稱為「標準算盤」的型制﹘ ﹘卅五檔、珠呈菱形、上一下四﹘﹘卻是日本改良的算盤，叫做「昭和算盤」，之前另有上一下五的「大正算盤」。