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

Spreadsheet


boards/ecb/zilog-peripherals/clock-divider.txt · Last modified: 2018/07/27 20:59 by b1ackmai1er
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