Fostex B-16 - Page 18

3) Display
The counter display is the dynamic scan type and can indicate from -1H59M
59S up to 9H59M59S. is indicated by using the "g" segment of digit 5.
This timing chart is shown in Fig. 4.5.
U2S-56
U23-24 Di
-25 02
-26 0
-27 0
-28 0
U2J- 4 4
-5b
-6c
- 7 4
- 8 e
- 3 I
- 10 q'
U25- I
U20-I5
U20- 6 g
Fig. 4.5
4) Counter LSI, U23
BCD out: When the digit codes are output by dynamic scanning from Dl
through D5, each display number is converted to BCD and output
by approximately the same timing as with the digit output.
For instance, if the Dl display number is "7 ” , the BCD codes will
be output in the following order from LSB throughout the duration
when Dl is at "H “ level: A=H, B-H, C=H, D=L.
r a r b R c : input terminal of the U23 internal register for storing the BCD
counter codes. Rp pin is not used.
Load register : The R A , R B , Re, R D codes are stored in the register when