[GreenKeys] TTY-CONNECT loop adapter thingy

[Gregory W. Moore]

GE Jack,
Put me down for a parts kit, or at least an etched PCB. Since I would 
like to have the option of both an ascii and baudot
interface, to use with the computer and Dovetron,  I would probably be 
interested in 2 of the units.  I am especially interested in speed 
conversion as well as both a high and low level loop, as I have machines 
set up for both.  I would be interested in the 'heavy metal' style of 
interface, so that I could demonstrate operation of the units by 
computer and the people seeing the units would only be watching the 
teletypes themselves, the computer being "out of sight, out of mind".... 
However, the speed conversion capability is a very necessary item for 
the use I plan to use them for...

so, put me down for at least a couple of PCB;s at least, if you are 
interested in settting up parts kits, so much the better. but I can live 
with the PC card and a schematic.....I do most sincerely, require both 
low level and high level outputs since I have both types of connections 
on various of my "heavy metal..
73 es tnx de Greg WA3IVX / NNN0BVN

gil smith wrote:

> Hi Jack:
>
> At 03:55 pm 8/14/03, Jack wrote:
>
>> Gil,
>>
>> Not sure what value the high-speed PC ASCII port would have without
>> any buffering built into the TTY-CONNECT board, unless there
>> is software for the PC that actually sends the high-speed stuff at
>> the speed that the TTY needs (through the micro-controller).
>
>
> This is easy -- no buffer needed.  Well, the micro has about a hundred 
> byte internal buffer that smooths out the serial port interrupt 
> routine, but when this gets near full, it sends the PC an XOFF char.  
> All further buffering is done in the PC until it gets an XON.  It is 
> all transparent to all involved, and allows any PC application that 
> can print to the serial port (eg: with the generic text driver), to 
> print to the tty at 19200 (or whatever).  The PC serial port just 
> needs to have XON/XOFF flow control enabled.
>
>
>
>> My two cents...I'd rather see some high-capacity buffering for
>> baudot speed converting. Heavymetal does agreat job of doing
>> all of the internal trickery and outputting TTY Baudot. What would be
>> nice would be to have a way to drive several machines at different
>> speeds (which is what I do with the "Black Box" gadget).
>
>
> Yes, for the baudot conversion, it needs to buffer the data for 
> hi-to-lo speed conversion.  All a question of how much.  I wrestled 
> with driving a big sram (with all the pins), and then realized that 
> speed should not be an issue.  So I'm going to put eeproms (nice 
> little 8-pin dips) in there.  Even with 5ms write cycle delays (per 
> char) for the eeprom, there is more than enough time to save chars.  I 
> wish they made the same package in a pure serial sram, with the same 
> I2C interface as the non-volatile eeproms, but I have only seen serial 
> srams in very small sizes.  I'll also provide a place on the board for 
> a daughter card (you never know what makes sense later on).
>
> Did you say that your black-box converter had 64K chars of 
> buffering?   Let's see:
>
> 100-wpm - 60-wpm = 40-wpm buffer fill rate, worst case, with streaming 
> text.
>
> At the standard 6-chars-per-word = 40 x 6 is approx 240 
> chars-per-minute fill rate.
>
> 65536 / 240 = 273 minutes to fill the buffer?  Is that about right?
>
> gil
>
>
>
>
>> Jack WA2HWJ
>
>
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-- 
"All that is necessary for the triumph of evil is that good men do nothing."
                                                   --Edmund Burke

Greg Moore NNN0BVN PA
U.S. Navy-Marine Corps Military Affiliate Radio System (MARS)
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