alesis midiverb ii
dsp
Markings on the chip (next to Texas Instruments logo) say: CF61252FN N 48816 8715. Googling doesn't help. The hint from a guy at Wavefront Semiconductor (that used to be Alesis Semiconductor before breakup) says that the specs were never released to public and probably no schematics or datasheets have survived even within the company. DSP chip in early MidiVerbs later evolved into Alesis SCR (Single Chip Reverb) giving some hints about what might be inside the MidiVerb DSP. If anyone could shed some light on the inner workings of the MidiVerb DSP chip (eg. in form of a data sheet!!) I would be almost eternally thankful.
The chip itself is a 68 pin PLCC. Poking around with DVM suggests the following pinout:
| Pin | Function |
| 1 | GND |
| 2-9, 61-68 | Sample memory data bus D0-D15 (16 bits) |
| 10-17, 19-26 | Data bits for Digital-to-Analog Conversion (16bit sample) |
| 18 | VDD |
| 27 | Analog demultiplexer INHIBIT signal |
| 28 | Voltage comparator output (End of conversion) |
| 29 | GND |
| 30 | 8 MHz DSP internal system clock |
| 31 | |
| 32 | OVLD (Overload) indicator control |
| 33-34, 36-41 | Program memory data bus D0-D7 (8 bits) |
| 35 | GND |
| 42-49 | Program memory address bus A0-A7 (8bits). A0 is also used as -RAS for DRAM. A5 is also used as 'deglitcher' control signal in analog demultiplexer. |
| 50 | -WR (DRAM) |
| 51 | -CAS (DRAM) |
| 52 | VDD |
| 53-60 | Sample memory address bus A0-A13 (14 bits, multiplexed) |