Looking for NS405-A12N Urgent!

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Looking for NS405-A12N Urgent!

Postby GrantM on Sun Oct 19, 2014 5:11 am

Hi guys,

Trying to find a NS405-A12N from National Semiconductor. It's a 48PIN DIP package and is basically a Video Terminal chip.
Also, if anybody knows the difference between the -A12N suffix and the -B18 suffix, I'd like to know, the datasheet doesn't really explain the difference - only mention of the difference is in the ordering details and that doesn't really say much at all.

Thanks
Grant
GrantM
 
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Re: Looking for NS405-A12N Urgent!

Postby tezza on Sun Oct 19, 2014 9:17 am

Grant,

Good luck on the search. It might help to know what vintage devices use this IC? Some of us might have some old junk around with the chip installed and not even realise we have it.
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Re: Looking for NS405-A12N Urgent!

Postby GrantM on Sun Oct 19, 2014 7:55 pm

Thanks Terry,
It has a Video generator, UART and the equiv of an 8048 inside, plus various glue logic internally and is designed as a Video Terminal chip, more or less like a VT100 type of thing, video terminals (perhaps inside other equipment) is the type of equipment it would be in - anything with a video terminal potentially. With me it's on what appears to be an S100 (or similar) type of board in a piece of industrial equipment, though it's not used in an S100 configuration and I suspect its perhaps mid-late 80's.

If it's possible to put attachements here (I can't see a way), then I could put up the first page of the National Datasheet, but alternatively the datasheet is available here http://www.datasheetarchive.com/dl/Scans-063/DSA2IH00122424.pdf.

The Datasheet says -
The NS405 is a CRT Terminal Controller on a Chip. It is a Microcomputer systems which replaces the following LSI circuits commonly found in a CRT Data Terminal:
-Microcomputer
-CRT Controller
-DMA Controller
-Character Generator
-UART
-BaudRate Generator
-Interrupt Controller
-Parallel I/O Controller
-Timer
The NS 405 is Primarily intended for use in low-cost terminals, but contains many features which makes it a superior building block for "smart" terminals and word processing systems...
GrantM
 
Posts: 5
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Location: Melbourne, Australia

Re: Looking for NS405-A12N Urgent!

Postby GrantM on Mon Dec 08, 2014 12:06 am

Well still no luck. I did manage to get hold of an NS405-B12N (instead of the A12N) and it sort of worked, but the characters are squashed up next to each other and cut-off on the right hand side, so a B looks like an E and a U looks like a backwards J, makes it very difficult to read. I don't know if that's because of a difference between the -A12N and the -B12N, as the datasheet just doesn't explain the difference. It could be something wrong with the character generator EPROM, but it's happening with all size characters, so I'm leaning towards the NS405.

The board is a Term-Mite ST1000 card and looks like it might be an S100 card, though the edge connector is not used in this application. If anybody has one or knows of one, I'd be very interested. Is there a way I can attach a PDF here?

Thanks
GrantM
 
Posts: 5
Joined: Sat Oct 18, 2014 10:08 pm
Location: Melbourne, Australia

Re: Looking for NS405-A12N Urgent!

Postby tezza on Mon Dec 08, 2014 10:11 pm

GrantM wrote:Is there a way I can attach a PDF here?

Unfortunately not Grant, but you can place it somewhere else (Dropbox?) and link to it here.

Good luck in the search. I had a look at some of my "junk" but no such IC I'm afraid.
Tez (Terry Stewart) (Administrator)
Collection: http://www.classic-computers.org.nz/col ... /index.htm
Projects and Articles: http://www.classic-computers.org.nz/blog/index.htm
Twitter: @classiccomputNZ | YouTube: Terry Stewart
Trade Me: tezza5
tezza
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Re: Looking for NS405-A12N Urgent!

Postby GrantM on Mon Dec 08, 2014 11:13 pm

Thanks Tezza,
I put a link to the datasheet above, but figured I'd post the first page in case it jogged anybody's memory. Anyway, that's fine. Let's hope somebody finds one somewhere!
Thanks for looking.
GrantM
 
Posts: 5
Joined: Sat Oct 18, 2014 10:08 pm
Location: Melbourne, Australia


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