<I know that it is a "one-shot". What does that
<mean? The pinouts in the Chip Directory are
74121, 122, 123 and 9601
Response is a pulse triggered by the inputs and the pulse length is
determined by the R*C values connected.
Common use is pulse shortening or pulse stretching.
<no help. Several seem to be involved in the
<DEPOSIT logic on the IMSAI front panel.
<Also, I can't quite figure out what the logic
<table for the 74107 is trying to say.
74107, JK-FF. J and K inputs setup what the FF will do when the Clock
input changes state (hin to low transistion).
Allison
At 07:35 PM 3/19/99 -0700, you wrote:
>
>Can anyone recommend a vendor for obsolete or discontinued chips? My
>specific current need is for an AMD chip: AM7992BCD (or equivalent).
>
www.alltronics.com in San Jose has a
AM7992ADC for $US 2.50. Don't know what the suffix means: package, speed, etc.
There is an expensive place that may even make some "obsolete" chips, I
think their name is Rochester Electronics.
-Dave
>I know that it is a "one-shot". What does that
>mean?
An external resistor and capacitor set a time constant. One-shots
produce output pulses, the width set by the time constant, in response
to certain changes in their inputs.
> The pinouts in the Chip Directory are
>no help.
"Well duh". Try a manufacturer's website, i.e. National Semiconductor's
Application Note #366, "Designer's Encyclopedia of One Shots", at
http://www.national.com/an/AN/AN-366.pdf
or Fairchild Semiconductor for the 74123 data sheet
http://www.fairchildsemi.com/pf/DM/DM74123.html
If you have a nearby university, you'll be able to find the 74123 in
just about any TTL databook from the last 25 years or so. While you're
there, you might find a copy of Horowitz and Hill's _The Art of Electronics_.
Note that the 74LS123 is incompatible, for many applications, with the
non-LS 74123. This is the boundary between analog and digital technology...
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
<me suspect there is some sort of special DEC CD-ROM holder cartridge. If
<so, is there any source for these? (I've got Sun ones but have never seen
<any others besides them.)
I think older sony used the same or was it panasonic.
Allison
I hope this is near enough on topic.
I started to create a standalone backup this morning aand have a problem. The backup process aborted because of a problem with the tape drive. The drive is now sitting there with all three lights flashing. If I press the 'unload' button all of the lights come on stadily for some time and then start flashing again.
Any suggestions as to what might be wrong, or at least how to diagnose the problem?
BTW I aam running VMS 5.2.
Regards
Pete
> I just got and RRD40 (external SCSI version that I'm going to "downgrade"
> to use with the KRQ50) and it has a very strange loading slot. This makes
> me suspect there is some sort of special DEC CD-ROM holder cartridge. If
> so, is there any source for these? (I've got Sun ones but have never seen
> any others besides them.)
Yep, I've got a few of the LMS caddies that fit the RRD40 left. Get me
your mailing address and one will go out ASAP.
Are you sure you really want to use the RRD40? It's slower than a 1X
CD-ROM... If you can at all get a more recent SCSI CD-ROM that you can
set to 512 bytes per sector (lots of such NEC units show up on E-bay
and at surplus dealers like www.hitechcafe.com) and use, do it. Most
third-party Q-bus SCSI controllers will issue SCSI mode selects so that
you can use drives that are set up for 2048 bytes per sector, even.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
<I started to create a standalone backup this morning aand have a =
<problem. The backup process aborted because of a problem with the tape =
<drive. The drive is now sitting there with all three lights flashing. =
<If I press the 'unload' button all of the lights come on stadily for =
<some time and then start flashing again. =20
<
<Any suggestions as to what might be wrong, or at least how to diagnose =
<the problem?
We would need to know more like what tape?
Allison
One last go at this.. (3rd time = charm??)
If anyone reading The List is familiar with RSTS/E V9.x (I am
running 9.7) I have a small perplexity.
I have performed a recent sysgen to add RL02, RK05, RX02, and
networking functionality to RSTS on my 11/44.
I have a pair of RL02s and an RL11 card installed in the machine.
The RL02 subsystem appears to function normally according to the
appropriate docs.
I can init the RL02s, I can erase and re-init, and during the
init process, if called for, the disk check patterns run to
completion and bad blocks (if any) are found and written to BADB.SYS.
I can mount the drives, and can see them mounted by SHOW DEV.
What I *can't* do is read or write to them... the error message
'device not available' results from trying to alloc, dir, or any
copy or pip operation.
I have tried mounting the /PUBLIC to no avail.
I have the RSTS Orange Wall coming, but it's not here yet... I'm
hoping I'm doing/not doing something dumb or obvious...
Thanks and cheers
John
Howdy,
I just got and RRD40 (external SCSI version that I'm going to "downgrade"
to use with the KRQ50) and it has a very strange loading slot. This makes
me suspect there is some sort of special DEC CD-ROM holder cartridge. If
so, is there any source for these? (I've got Sun ones but have never seen
any others besides them.)
--Chuck
I imaginge thta this is fairly off topic but I sincerely have no idea how
old it is.
A while ago I aquired a MaxSpeed VGA MaxStation X terminal. Nothing with
it, so I emailed MaxSpeed and they sent me a free PSU. I hooked up an SVGA
monitor, mouse, and keyboard, and plugged in my ethernet cable. When I
turn it on, the power light just blinks (short, long, short, long, etc)
over and over again. Nothing happens on the CRT, but the keyboard lights
blink momentarily.
Any ideas?
Thanks,
Kevin
-------------------------------------------------------------------------------
"It's you isn't it? THE BASTARD OPERATOR FROM HELL!"
"In the flesh, on the phone and in your account..."
-- BOFH #3
