Well, I’ve been coding on it the last 5 days on and off, and it mostly works. I made an SP0256 emulator on the PIC18F! I also dumped my set of SP0256’s including the SP0256-017 SP0256-018, the -004, -012, -019, -053, -060 and -AL2. I dumped a bunch of SPR128’s and SPR016’s also.
The emulator mostly works now, and only two of the allophones in the AL2 chip don’t seem quite right. I had alot of “fun” cramming 480K multiplies/sec into the code, and everything is incredibly optimized. The LPC “core” itself takes around 56% of the CPU while it is running. The chip spits out 10KHz 10 bit samples to an external DAC, but it could just as easily use the PIC’s PWM output. The SP0256 uses a 7 bit PWM output which you then lowpass filter to produce it’s audio output.
Wonder if anyone would be interested in a “true” SP0256-AL2 replacement that doesn’t cost $20-$30? I could also make SP0256-??? replacements of any other SPxxxx chips, like the SP0256-017 talking clock chipset. The PIC has enough room for up to 40K or so of speech data, and I stuck the two speech ROMs from the -019 (Odyssey^2 “The Voice”) onto it and was playing around. Though htere appears to be a problem or two with one of the SP0256 opcodes in the microsequencer still.
Hopefully later I will have some audio samples up and a pic of the board… tho the board isn’t much to look at, just a piece of perf with 2 chips on it.