/* Imported from Wayback Machine
   Original URL : https://retrobrewcomputers.org/doku.php?id=boards:ecb:zilog-peripherals:clock-divider
   Snapshot date: 2025-02-14
   Generator    : wayback-archiver
*/

====== 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    |

[[https://retrobrewcomputers.org/lib/exe/fetch.php?media=boards:ecb:zilog-peripherals:clock-divider:clkdivtbl.xlsx|Spreadsheet]]

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