Universal Midi Keyboard Interface Final Part

34 UNIVERSAL MIDI KEYBOARD INTERFACE Table 3 shows a practical example of how the EPROM contents can be adapted to the available keyboard, in this case a 72-key type with a range from F to E. As dis- cussed last month, programming the EPROM is simply a matter of entering the actual key numbers in ascending order, starting with the lowest key. Note that the most-significant nibble of each pro- grammed byte is 0, 2, 4, 6 or 8. The practi- cal connection of this keyboard is shown in Fig. 6b in last month"s instalment. Since there are 72 keys, 5 decoder boards are required to cover the 6 octaves. Programming one"s own EPROM is, fortunately, not required in most cases, since the EPROM supplied through the Readers Services (ESS575) provides the data required for a 96-key C-to-B key- board (8 octaves). Most keyboards are smaller and will not require a repro- grammed EPROM if their contacts go to the correct inputs on the decoder boards. Construction The construction of a MIDI keyboard en...