Mup21, features.

[Wayne Morellini <waynem1@xxxxxxxxxxxxxxxxx>]

Well hi guys.

The other day I realised that the Video processor on the Mup21 is just a
glorified D/A DMA machine, so if you can modulate a picture out on a
specific frequency, why not the sound channel as well.  Well I looked up my
copy of the Mc grawlls Television handbook and of course the sound channel
is modulated at a different frequency (that is too far away from the TV
frequency), but I did notice that picture elments can effect the sound
channel.

So I am woundering if it is possible to structure the Video image in such a
way as to produce sound on the sound channel (as they would be modulated on
waves with each other in real life).  Has anybody tried this and did you
get it to work ?

Origionally I had complementated using an D/A converter to
pick a digital sample off the buss in the reponse to the vertical blanking
code in the video memory.  So that as soon as this code came up in a memory
read it would copy the contents to the D/A converters and produce a signal. 
But I do not know if this would leave enough horizontal blanking spaces to
do the job.

I came accross something interesting in a jornal the other day, it was
called NVSRAM I think, by a company called Simtek, I think they used to
produce 6502 chips.  The company claimed that they were non-volatile,
operated at 25ns, something I can't rember but it led led me to beleive they
were not flash and did not have limited write cycles, and available is sizes
upto 256KB.  Well this was very interesting, a chip that could replace
bother rom and ram in a design?  If the 256KB was available in 32-bit
version (some srams are) then one NVSRAM and MUP21= 1 computer
(simplictically speaking).  If in 8-bit versions, 3*8-bit NVSRAM= 256kwords
of memory.

What is the real problem with getting sram to work accross the address
range of the mup21 anyway.  I thought that Dram was a superset of sram
anyway (better go back and read up).

Well if it was possible then you should get 80mips most of the time.


Also soon I am going to finish the Mup21 kit off and try clocking the video
at a higher freqency as I read somewhere recently was possible.  If the
Mup21's video processors output is directly dependent on the clock input
then I am going to see if I can do higher resolution and change the colour
phase signal on a finer angles to see if I can get a 80 column display and
more colours (if only  (  ).  If anybody has tried this, I would look forward
to your comments.

I have just had a look at the p-16 design in more on Forth engines and
wonder if it's not possible to do it on the p-21.  Without looking at the
instruction format I was thinking that the 5 of the 20-bits of data read in
could be hardwired externally to a no op instruction, so the other 3
instructions could be used with 16-bit memory.


Wayne.


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