UPD4991A и другие
| Компонент | Описание | Производитель | |
| UPD4991A | 4-BIT PARALLEL I/O CALENDAR CLOCK |
NEC |
 |
| UPD4991ACX | 4-BIT PARALLEL I/O CALENDAR CLOCK |
NEC |
|
| UPD4991AGS | 4-BIT PARALLEL I/O CALENDAR CLOCK |
NEC |
|