ALESIS HR-16 - Manual (Page 11)

HR-16/HR16B Service Manual 1.00 5
4.0 DM3AG ASIC
The DM3AG ASIC is a complex LSI device, specifically designed for the purpose of playing
percussion samples. Obviously, the internal workings of such a device are beyond the scope of this
manual. However, a brief description of some of the important pins follows.
NAME PIN#(s) Function
MD0-MD7 27-34 8031 Data Buss Input.
CLOCK 37 Asic Clock Input (6MHz in HR-16).
DAC0-DAC16 42-51, 53-60 Output to DAC.
A0-A19 3-17, 19-23 Mask Address Buss
D0-D7 61-68 Mask Rom Data Buss
SNH0 39 Output Sample and Hold Control
SNH1 40 " " " " "
SNHIN 41 Output Sample and Hold Inhibit.
STRES 26 Instruction reset strobe.
STB 25 Instruction latch strobe.
4.1 Mask ROMs
The mask ROMs contain the all of the sample information. The 18 bit address buss allows for
2 megabytes per mask ROM. Address line A19 from the ASIC is actually used in conjunction with
Q15 to switch the Mask ROM CE lines (pin 22) such that only one device is enabled at any given
time.
Diagram 5
Diagram 4