In the 1970s, this was acceptable for media such as text mode computer terminals, telegrams, receipts, or other electronically handled data.

However, it didn't match the industry requirements because the character map was small, and the code layout was impractical.

The AIST considered a practical character encoding to replace various codes used in Japan.

AIST committed the conjunction of ISO R 646 and katakana mapping to the Information Processing Society of Japan (IPSJ).

Some committee members criticized it would complicate the mechanic of keyboards which only handled normal katakana characters.

The ISO committee had two options that to use a generic currency symbol (¤) or to give the dollar ($) and pound (£) signs permanent assignments.

[2] The JIS committee decided to put the yen sign (¥) in 0x5c (one of national use positions).

The first half (Roman set) of JIS X 0201 constitutes a Japanese variant of ISO 646, amounting to ASCII with backslash (\) and tilde (~) replaced by yen (¥) and overline (‾),[5] while the second half (Kana set) consists mainly of katakana.

[10][11] The substitution of the yen symbol for backslash can make paths on DOS and Windows-based computers with Japanese support display strangely, like "C:¥Program Files¥", for example.

[14] Another similar problem is C programming language's control characters of string literals, like printf("Hello, world.¥n");.

Accordingly, when converting JIS X 0201 katakana (or Unicode half-width kana, which use the same layout) to ISO-2022-JP, the following mapping or transformation is often used.

For ease of comparison with the chart above, the mapping is shown below over the JIS X 0201 katakana encoding and with the high bit set.

[24] Another variant, including a smaller subset of these C0 replacement graphics (including only the box drawing characters in 0x01–06, 0x10, 0x15–17 and 0x19 and the line/arrow characters in 0x1B–1F), but using a different style of up-arrow (U+21E7 ⇧ UPWARDS WHITE ARROW) at 0x1C, is designated Code page 1086.