Re: Data Sheets

From: Nicolas Welte (
Date: 2000-02-12 14:16:45

Richard Atkinson wrote:
> No, but the Magic Voice (and I'm guessing the V364) contain speech data in
> their own ROMs which (at least in the case of the Magic Voice) they copy
> to RAM. I'm pretty certain the Commodore implementation of the T6721A
> makes speech accesses out of RAM, though I don't know how it does it -
> programmed I/O, DMA or whatever.

I also didn't do an in-depth analysis, but the notes I took while
repairing my Magic Voice show that there is a four bit data path in the
module itself that seems to supply speech data and maybe commands to the
speech chip: data from PA0-3 of the 6525 is sent to the 16 word (rather
nibble) deep FIFO CD40105 which then sends its output to the gate array.
There are only four lines lines between the speech chip and the gate
array, and one of them connects to the 'data-in ready' line of the FIFO
as well. So my guess is that the gate array performs 4bit parallel to
serial conversion and also handles data requests from the speech chip.

All connections between C64 and speech chip go through the 6525 first,
so data transfer is pure PIO, though the Magic Voice can generate NMIs
to request data. Much of the 6525 and the gate array are used to control
the pass-through expansion port and the C64 memory configuration lines,
so very probably the single 28pin 8706 chip in the V364 could integrate
the system to speech chip interface, including the FIFO. At least I
don't remember that Bo listed this or a similar chip in his V364

> Please make sure you scan the sheet in its entirety, including these
> ROMs. I once had a datasheet for the Texas TMS5500 (the chip in the Speak
> and Spell) and it made references to seperate ROM chips, but these may
> have been serial ROMs and it was clearly a different implementation to
> that in the Magic Voice / V364.

Now that it looks like the Toshiba chip also uses serial communications
it might be more similar to the Texas chip than we thought.


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