Re: 264/TED/Plus4 Story

On 08/29/2011 09:12 PM, Hársfalvi Levente wrote:
>
> 318030-01 is based on 318004-04, replacing some graphical characters only.
>
> The other (so far only found in eprom) version is originally 318004-05,
> and it also contains further modifications to the character set. The one
> that I have here is in a NEC 27C128, whose datecode appears to be 8614
> (see photos) ie. it had to be programmed after the spring of 1986.

I try to remember the difference between the -04 and -05. It was an easy 
to reproduce bug and back then I was pretty annoyed when I found out 
that my first C16 had the -04.

It's not the well known math crash that can be triggered with

  ?5+"A"+-5

this one still works with -05.


> As to how and why these (new) differences in the character set?
> Honestly, I don't know (...I have no idea about especially the few
> graphical characters that have been modified). Also, someone's yet to
> find a Plus/4 with the first and a C16 with the second version; I could
> never encounter either of those combinations yet.

Maybe the Plus/4 was imported later when all the C16 were already sold 
and they decided to finally fix the bug from -04? On the other hand, the 
first -05 PAL kernals are from the end of 1984.


> Well, I think I know the technical details of the PAL-N machine fairly
> well (see http://coroners.no-ip.hu/dc16 and
> http://coroners.no-ip.hu/c2rgb for details). Unfortunately, speaking of
> its story, that'd not be the case (...beyond things that one can read
> around the net), which is a pity.

I'd be interested in that story as well. I mean making new TEDs just to 
export the 264 systems to south america? Ok, they only modified the 
existing TED slightly, but it's still a whole new production run 
including testing.


> It's interesting how things "converge" to similar solutions, given
> similar-ish initial conditions. I've never really used Eproms but
> created a small flash board with a cmos priority encoder + a 128k flash
> chip sometime ago.

Back then I got a cheap EPROMmer that had 2 sockets and could do certain 
things on its own (like copy). Which made it very easy to migrate the 
ROMs to CMOS EPROMs. Otherwise it's very slow. It still works though.


> It never made it past the prototype stage and it
> still looks very hacky, but well, it too, reduces current consumption of
> the machine by a reasonable percent. (...You can also find a photo of
> that hack - it's in fact a flash + PAL/NTSC switch hack together - at
> http://coroners.no-ip.hu/stuff/ ).

Interesting... But why make a C16 switchable between PAL and NTSC? Is 
there something only an NTSC system can do? Or is it the 60Hz you wanted?

You have the 74LS257 socketed but the RAMs are soldered?

I also put heatsinks on CPU, TED and PLA to hopefully extend their lives.

  Gerrit




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