29 Sep
2008
29 Sep
'08
9:34 p.m.
On Monday 29 September 2008 23:48, Ethan Dicks wrote:
I'm not familiar with that one, offhand (and don't have it in my big generic
numbers chart).
I saw the picture of those but don't recall ever actually seeing those
devices.
Yep. I wouldn't mind getting some nixies to play with too, but those are
getting way too complicated too. And are the driver chips for them available
at all any more? What was it, the 7441?
I have a few LCDs I've been meaning to play with, and some VFDs out of
scrapped VCRs, most of which are too application-specific for me to want to
do anything much with them but one or two of the more recently-acquired ones
might be nice to do something with. Tony mentioned some trick in the past
week or two for a similar type of device, though I think that was only a
single indicator, as far as making it work, and I was wondering how that
might apply to a whole display...
But I'm having to spend too much time weeding things out, arranging stuff,
and trying to get things more organized that I haven't had the time to play
with any of it lately, and it'll be a while yet before I get to that point.
Oh well. :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
On Mon, Sep 29, 2008 at 08:42:38PM -0400, Roy J.
Tellason wrote:
I miss those stores. Somebody'd posted in here not too long ago about one
place that was still left there that was supposed to be closing up soon, I
think? I never did find out just when that was gonna happen. We were in NYC
on 9/5 for a wedding, but didn't have time to pursue interests like that as
the next day with that storm coming up the coast I ended up in Cape May
County for a funeral.
Maybe my passion for collecting junk and parts has something to do with having
spent so much time in those stores? Nah, that couldn't be... :-)
BTW, the guy whose name was on the first linked page is who ended up with the
one 1802-based system I had, and also the -8 that I had.
On Monday 29 September 2008 18:44, Ethan Dicks
wrote:
Nice. We used to have a short block of surplus stores in Columbus while I
was growing up (I picked up a couple cardcages with "Gorf" arcade game
cards and got them working later), but nothing like Canal St. Hi, All,
Since one of the first computers I ever got my hands on as a kid (Quest
Elf) happened to have TIL311 HEX displays, I've long been fascinated
with display technology of that vintage...
They still look cool, though, and that's the real point.
Yup!
This is neat stuff...
I built a digital counter for a guy back in 1975, using TTL and displays
that I bought on Canal St. in NYC. I still have some number of that sort
of display around, and haven't figured on any particular use for them
yet, plus some that I've salvaged a bit here and there, some two-digit
parts, etc. No 7446/7
chips on hand to drive them with, though. Or any of the
4000-series CMOS either. :-(
I have one or two of a few different types, but no loose 9368s (only
installed in boards already). One thought I had for trying to use a
reduced-pin-count MCU-based numeric
display was a 7447-type chip on 4-bits of an I/O port, and a 74145-type
BSD decoder on the other half of the port - up to 10 digits easily, or 9
with simple blanking (write 0 to the '145 and don't hang a digit off of
it).
Sounds to me like it oughta work. I have some nontrivial discussion of
driving those devices in the _8085 Cookbook_, but it's been a rather long
time since I read it. I do recall them talking about how important it was to
have some way of not pushing too much current through multiplexed displays
when things weren't running yet, or in case of program bugs, etc.
Just checking now, it looks like the CD4511 won't
render any digits if you
give it an input over "9"
I haven't looked at that aspect of that chip.
(the 7447 has incomplete decoding internally, so will
light various odd
segments if you don't stick to 0-9).
With blank for F IIRC, and I always wondered why they did it that way.
With a CD4511, then (and a 74145 or CMOS equiv), one
could hook up to 10
digits and just write "F"s to any positions you wanted to blank.
I don't know what the heck I'd do with ten digits worth of that stuff
though. :-)
There used to be a number of interesting digit and
segment driver chips
like the ICM7218D (most famously found in Dragon's Lair and Space Ace
scoreboards), but many of them are difficult to find now, and most of
them cost $8 or more new (and still do when you can find them).
I seem to recall Radio Shack selling a couple of chips for that purpose,
75491 and 75492. The former had two sets of outputs but fairly limited drive
capabilities, while the latter was open-collector but could drive a good bit
more if I'm remembering right. They didn't seem to be too friendly to
common-anode displays, which is what I was wanting to use at the time.
They do make things easy, though, as long as they
provide enough digits (the
DL/SA scoreboard has 16 total digits and a pair of ICM7218D to drive them).
I'm going to have to see if I can remember to snag a datasheet on those at
some point.
They are as easy to talk to as a 6522 or 6821 - R/W,
register select and
4-bits input - meant to be memory-mapped, but quite easy to talk to on
the other side of a PC parallel port, for example.
I seem to recall Osborne using one of those, might've been the 6821, and I
don't think it took too much in the way of glue logic to make it work on the
z80 bus.
Since I have a couple, my only "problem" is
that I haven't found an
integrated multi-digit driver chip that drives more than 8 digits
(and using two of the aforementioned driver chips to drive, say, 6+4
digits substantially increases the project cost).
Yeah, there was a time when I immersed myself in those sorts of ideas too,
and the chips never seemed to go quite as far as I wanted 'em to. :-)
I was always
wanting to get my hands on some of those hex or better yet
5x7 displays back in those days to play with. Oh well.
Back in the day, I just had two TIL-311s and they were attached to my Quest
Elf. I did take a pair of raised-segment LEDs and hook them up to the
User Port on my PET and wrote a simple interrupt wedge to grab a normally-
unused zero-page byte, and at about 30Hz refresh, blast out a pair of
hex digits. I built it when I was 13-14, but I still have it around
somewhere in the bottom of a drawer. Definitely
nifty stuff, for sure.
Oh, yeah. So are small textual and graphical LCD and VFD displays, but
there's a real appeal, to me at least, of the soft glow of red LEDs. Not
quite as cool as Nixies, but those evoke memories of a different era.