Z80 SIO divider & jumper table for standard crystals:
The available board rates that can be provided by the SIO/DART are determined by the selection of:
- Crystal clock selection
- Clock divider selector X5
- SIO/DART internal clock divider.
A wide range of board rates can be selected through this combination but for any Crystal:Divider selection, only four board rates are available to be selected by software control.
For example, with a 4.9152Mhz crystal and X5 set for a /8 divider by link pins 9-11 the available baud rates that can be selected through software are 614400, 38400, 19200 and 9600 baud.
Note /1 divider is not available for selection on X5 but is shown for completeness.
X5 JUMPER | 1.8432 | Mhz | 2.4576 | Mhz | 4.9152 | Mhz | 7.3728 | Mhz | ||||
1843200 | Div | Baud | 2457600 | Div | Baud | 4915200 | Div | Baud | 7372800 | Div | Baud | |
NO DIV | 1843200 | 1 | 1843200 | 2457600 | 1 | 2457600 | 4915200 | 1 | 4915200 | 7372800 | 1 | 7372800 |
/1 | 16 | 115200 | 16 | 153600 | 16 | 307200 | 16 | 460800 | ||||
32 | 57600 | 32 | 76800 | 32 | 153600 | 32 | 230400 | |||||
64 | 28800 | 64 | 38400 | 64 | 76800 | 64 | 115200 | |||||
Q0A 13-14 | 921600 | 1 | 921600 | 1228800 | 1 | 1228800 | 2457600 | 1 | 2457600 | 3686400 | 1 | 3686400 |
/2 | 16 | 57600 | 16 | 76800 | 16 | 153600 | 16 | 230400 | ||||
32 | 28800 | 32 | 38400 | 32 | 76800 | 32 | 115200 | |||||
64 | 14400 | 64 | 19200 | 64 | 38400 | 64 | 57600 | |||||
Q1A 11-12 | 460800 | 1 | 460800 | 614400 | 1 | 614400 | 1228800 | 1 | 1228800 | 1843200 | 1 | 1843200 |
/4 | 16 | 28800 | 16 | 38400 | 16 | 76800 | 16 | 115200 | ||||
32 | 14400 | 32 | 19200 | 32 | 38400 | 32 | 57600 | |||||
64 | 7200 | 64 | 9600 | 64 | 19200 | 64 | 28800 | |||||
Q2A 9-11 | 230400 | 1 | 230400 | 307200 | 1 | 307200 | 614400 | 1 | 614400 | 921600 | 1 | 921600 |
/8 | 16 | 14400 | 16 | 19200 | 16 | 38400 | 16 | 57600 | ||||
32 | 7200 | 32 | 9600 | 32 | 19200 | 32 | 28800 | |||||
64 | 3600 | 64 | 4800 | 64 | 9600 | 64 | 14400 | |||||
Q3A 8-10 | 115200 | 1 | 115200 | 153600 | 1 | 153600 | 307200 | 1 | 307200 | 460800 | 1 | 460800 |
/16 | 16 | 7200 | 16 | 9600 | 16 | 19200 | 16 | 28800 | ||||
32 | 3600 | 32 | 4800 | 32 | 9600 | 32 | 14400 | |||||
64 | 1800 | 64 | 2400 | 64 | 4800 | 64 | 7200 | |||||
Q0B 7-8 | 57600 | 1 | 57600 | 76800 | 1 | 76800 | 153600 | 1 | 153600 | 230400 | 1 | 230400 |
/32 | 16 | 3600 | 16 | 4800 | 16 | 9600 | 16 | 14400 | ||||
32 | 1800 | 32 | 2400 | 32 | 4800 | 32 | 7200 | |||||
64 | 900 | 64 | 1200 | 64 | 2400 | 64 | 3600 | |||||
Q1B 6-8 | 28800 | 1 | 28800 | 38400 | 1 | 38400 | 76800 | 1 | 76800 | 115200 | 1 | 115200 |
/64 | 16 | 1800 | 16 | 2400 | 16 | 4800 | 16 | 7200 | ||||
32 | 900 | 32 | 1200 | 32 | 2400 | 32 | 3600 | |||||
64 | 450 | 64 | 600 | 64 | 1200 | 64 | 1800 | |||||
Q2B 3-5 | 14400 | 1 | 14400 | 19200 | 1 | 19200 | 38400 | 1 | 38400 | 57600 | 1 | 57600 |
/128 | 16 | 900 | 16 | 1200 | 16 | 2400 | 16 | 3600 | ||||
32 | 450 | 32 | 600 | 32 | 1200 | 32 | 1800 | |||||
64 | 225 | 64 | 300 | 64 | 600 | 64 | 900 | |||||
Q3B 3-4 | 7200 | 1 | 7200 | 9600 | 1 | 9600 | 19200 | 1 | 19200 | 28800 | 1 | 28800 |
/256 | 16 | 450 | 16 | 600 | 16 | 1200 | 16 | 1800 | ||||
32 | 225 | 32 | 300 | 32 | 600 | 32 | 900 | |||||
64 | 112.5 | 64 | 150 | 64 | 300 | 64 | 450 |