3.
MrX Expansion Bus K3
The MrX Interface is supplied with a built in expansion bus (K3) which allows direct access to the
signals provided by the YM2149 sound chip, should you wish to develop an add-on daughterboard.
Pinout K3:
1) IOB7
Port B from YM2149
2) IOB6
Port B from YM2149
3) IOB5
Port B from YM2149
4) IOB4
Port B from YM2149
5) IOB3
Port B from YM2149
6) IOB2
Port B from YM2149
7) IOB1
Port B from YM2149
8) IOB0
Port B from YM2149
9) IOA7
Port A from YM2149
10) IOA6
Port A from YM2149
11) IOA5
Port A from YM2149
12) IOA4
Port A from YM2149
13) IOA3
Port A from YM2149
14) IOA2
Port A from YM2149
15) IOA1
Port A from YM2149
16) CHL
Left channel of 3,5mm jack, behind capacitor
17) CHR
Right channel of 3,5mm jack, behind capacitor
18) GND
Ground
19) /CLK
ZX81 clock signal 3,25 MHz
20) GND
Ground
21) ANALOG_CH_C
Analog Channel C directly connected to YM2149
22) ANALOG_CH_B
Analog Channel B directly connected to YM2149
23) ANALOG_CH_A
Analog Channel A directly connected to YM2149
24) VCC
Supply c5V
25) GAL1
Pin 15 of GAL 16V8
26) GAL2
Pin 14 of GAL 16V8
27) GAL3
Pin 13 of GAL 16V8
28) GAL4
Pin 12 of GAL 16V8
29) clock/2
1,625 MHz
30) IOA0
Port A from YM2149
Version: v005
6
Date: 22.05.2012
