> On 2024Apr 4,, at 7:22 AM, Adrian Godwin via cctalk
> wrote:
>
> This 'scope clock also uses circle generators rather than vectors to
> produce well-formed characters. It mentions a Teensy controller so I don't
> think it's the original made in this way - the first I heard of was too
> long
On 2024Apr 1,, at 3:33 PM, Just Kant via cctalk wrote:
>
> I have more then I need. All the working ones are HP w/color crts, and as far
> as older, verifiably vintage tools (right down to the 680x0 processor in
> either) I have to admit I favor them as a brand. Call we an oddball, weird
>
On 2023-Nov-21, at 1:03 AM, ED SHARPE via cctalk wrote:
> On Mon, Nov 20, 2023 at 7:01 PM ben via cctalk wrote:
>> On 2023-11-20 5:36 p.m., Murray McCullough via cctalk wrote:
>>> On Nov. 15, 1971 Intel commercially released the 4004 microprocessor which
>>> some consider to be the first.
On 2023-Sep-28, at 3:55 AM, Tom Hunter wrote:
> Thank you very much Brent !!!
>
> Your explanation beautifully clarified how the H7441 works.
> I have asked the same question over at vcfed.org without an answer..
> I hope it is Ok to share to vcfed.org what you wrote as others are likely to
>
On 2023-Sep-28, at 12:29 AM, Brent Hilpert via cctalk wrote:
> ...
> Excessive current through Q5 produces a V-drop across R10 which may turn on
> Q7 to take the PWM-mono into reset (E2.4=low).
> D7,D8,R3 clamp and sink reverse voltage/energy from the T1 secondary to avoid
> re
On 2023-Sep-27, at 9:01 PM, Tom Hunter via cctalk wrote:
> The DEC H7441 regulator is a relatively complex circuit using 2 x 555
> timers, 2 x LM301 op-amps, 2 x transformers and 2 inductors
> I am struggling to understand how it is meant to work and was hoping to
> find a maintenance manual for
On 2023-Sep-16, at 8:52 AM, Shoppa, Tim via cctalk wrote:
> Not quite computer tech but I figure this is the best place to ask:
>
> Does anyone recognize the display tech that was used on the Concorde's
> in-cabin display?
>
> Examples:
> https://samchui.com/wp-content/uploads/2016/02/CON15.jpg
On 2023-Aug-20, at 5:32 PM, Eric Moore via cctalk wrote:
> https://youtu.be/-CaUafVqnbw
>
> Super stoked to be able to share my latest video, I hope yall like it.
>
> -Eric
I'll third Ken and Rick's comments.
Nice to see this restored as its original-use system - the CPU together with
the
On 2023-Jul-05, at 9:45 AM,
wrote:
> Thank you! I couldn't remember if I'd posted it here before, I've been off
> the list for a while.
>
> Because I don't know really anything about it, I'd been operating on the
> belief the power sent from the PSU was DC. So maybe that's my issue. There
On 2023-Jul-05, at 8:25 AM, Brad H via cctalk wrote:
> Seems to be RS-232 compatible, which in my experience is unusual for a
> terminal in the early half of the 1970s. It has little serial number
> stickers tucked around but they're all random numbers, nothing really lines
> up. A few of
On 2023-May-25, at 1:43 PM, Rob Jarratt via cctalk wrote:
>
> This evening I went to check Vstart for any oscillation. However, all of a
> sudden, the current draw is down to 85mA and PWM has started working. I am at
> a loss to explain it. I wondered if there might be a dry joint, but I have
> On 4/22/2023 6:14 PM, Jay Jaeger wrote:
>> I have an HP 2875B paper tape drive that I want to interface to. It has a
>> 50 pin block connector (using well under 1/2 the pins). The connector
>> manufacturer was Continental.
>> I have already discovered, the hard way, that it is not a
On 2023-May-11, at 7:41 PM, Cameron Kaiser via cctalk wrote:
> it's actually an artifact of the monitor that the upper 6 were clear.
> Actually,
> the stuck bit is entirely bit 2 (i.e., it goes
>
> 0 1 2 3 4 5 6 7 8 9 a b c d e f
> 0 1 2 3 0 1 2 3 8 9 a b 8 9 a b
>
> and the high nybble is OK).
On 2023-May-09, at 11:08 AM, W2HX via cctalk wrote:
> I see some altairs have a metal escutcheon on the bottom with the stylized
> words "MITS ALTAIR 8800 COMPUTER" whereas others, the front panel is just the
> dark faceplate top to bottom. What is the difference? Would one have been a
> kit
On 2023-May-09, at 12:28 AM, Brent Hilpert via cctalk wrote:
> I thought I must be off somewhere by 10^n when first doing the calc. The 51Ω
> is 3 orders of magnitude away from the 0.01Ω on the other outputs, so a
> similar diff could be anticipated on the current sense.
>
>
On 2023-May-08, at 12:27 PM, Peter Coghlan via cctalk wrote:
> However, Brent's calculations show that the current trip value for the -12V
> line is as low as 1.3mA and I can't see any reason to disagree with his
> calculations or his conclusion that this seems very low (except that another
> tiny
is nonetheless higher than would be expected from the trickle current
available.
Which brings me to this, in reply to earlier message:
On 2023-May-08, at 5:03 AM, Rob Jarratt wrote:
>> From: Brent Hilpert
>>
>> From earlier measurements and the 45uA calc of current through
On 2023-May-07, at 1:54 AM, Rob Jarratt via cctalk wrote:
> The comments about the tolerance of the 7812 were right, it doesn’t appear to
> be an issue with the replacement 7812 regulator because when I tried using
> the bench PSU to feed exactly 12V to the circuit from the output of the 7812
>
On 2023-May-01, at 2:25 AM, Peter Coghlan via cctalk wrote:
> It seems a bit odd that a power supply from someone like DEC of that era would
> be designed to depend so critically on the absolute value of a rail used
> for startup purposes.
Further to Peter's point above, the 1988 NatSemi databook
On 2023-Apr-23, at 8:04 AM, Peter Coghlan via cctalk wrote:
...
> This should result in a current
> of about 45 microamps flowing to ground through those components mentioned.
...
> It ought to be possible to measure the same 0.6V across the diode to confirm
> this is where it is being dropped
On 2023-Apr-22, at 3:53 PM, Peter Coghlan via cctalk wrote:
On 2023-Apr-22, at 1:07 AM, Rob Jarratt via cctalk wrote:
>> This seems to be because I measure a steady 0.6V on pin 6 of the transformer
>> (p4, PSU Sheet 3). I just can't imagine where it might be coming from as the
>> chopper won't
On 2023-Jan-21, at 10:14 AM, Chris via cctalk wrote:
> And if your lids aren't gold plated, is the lid aluminum or some related
> alloy?
Tin-plate on copper would be likely, easy to solder-seal on. Al would not
solder on easily.
Tin does make a nice plating. Even HP made some lab/computing
On 2023-Jan-21, at 11:25 AM, Mike Stein via cctalk wrote:
> Finally, some Burroughs memory boards containing what I think are 2102s,
> but I'd have to investigate.
Soldered or socketed?
I'm on the lookout for 16 (or more to have some spares) 2102s to populate an
EconoRAM S100 memory board to
On 2022-May-15, at 3:53 PM, Eric Smith wrote:
> On Sun, May 15, 2022, 13:03 Brent Hilpert via cctalk
> wrote:
> On 2022-May-15, at 1:16 AM, Eric Smith via cctalk wrote:
> > On Sat, May 14, 2022, 16:09 ben via cctalk wrote:
> >> On 2022-05-14 11:50 a.m., Nigel John
On 2022-May-15, at 1:16 AM, Eric Smith via cctalk wrote:
> On Sat, May 14, 2022, 16:09 ben via cctalk wrote:
>> On 2022-05-14 11:50 a.m., Nigel Johnson Ham via cctalk wrote:
>>> AFAIR LS can only drive one unit TTL load.
paul
>> LS is 4 TTL, 4 ma low.
>> Was there a trick of forcing the
On 2022-Apr-01, at 11:51 AM, Paul Koning wrote:
>> On Apr 1, 2022, at 2:38 PM, Brent Hilpert via cctalk
>> wrote:
>> On 2022-Apr-01, at 6:02 AM, Paul Koning via cctalk wrote:
>>
>>> When I looked at that ebay listing of "glass memory" it pointed me to
On 2022-Apr-01, at 6:02 AM, Paul Koning via cctalk wrote:
> When I looked at that ebay listing of "glass memory" it pointed me to another
> item, https://www.ebay.com/itm/265623663142 -- described as "core rope
> memory". Obviously it isn't -- it's conventional core RAM. Interestingly
>
On 2022-Apr-01, at 10:52 AM, Chuck Guzis via cctalk wrote:
> On 4/1/22 10:27, Paul Koning wrote:
>>
>>> On Apr 1, 2022, at 1:25 PM, Chuck Guzis via cctalk
>>> wrote:
>>>
>>> Wasn't some of this glass delay line memory used in early raster-scanned
>>> computer video displays?
>>
>> I don't
On 2022-Apr-01, at 5:54 AM, Paul Koning via cctalk wrote:
>> On Apr 1, 2022, at 2:56 AM, Mark Huffstutter via cctalk
>> wrote:
>>
>> https://archive.org/details/TNM_Glass_computer_memories_-_Corning_Electronics_20171206_0185
> ...
> That Corning document is also interesting because of its
On 2022-Mar-31, at 7:44 PM, Noel Chiappa wrote:
>> From: Brent Hilpert
>> DCLO & ACLO behave as power-on-reset signals to the system.
>
> Minor nit: actually, I think it's DCLO which performs that function in a lot
> of places; see e.g. the latches on pg. K2 (pg. 153
On 2022-Mar-31, at 8:05 PM, Anders Nelson via cctech wrote:
> Hey all, found this on eBay:
>
> https://www.ebay.com/itm/Corning-Glass-memory-/125087612899
>
> I can't find any info on it - was it some kind of delay-line or magnetic
> laminate stack?
>
> Interesting!
Very interesting - there
On 2022-Mar-31, at 11:56 PM, Mark Huffstutter via cctalk wrote:
> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Brent
> Hilpert via cctalk
> Sent: Thursday, March 31, 2022 11:53 PM
> To: General Discussion: On-Topic and Off-Topic Post
On 2022-Mar-31, at 8:05 PM, Anders Nelson via cctech wrote:
> Hey all, found this on eBay:
>
> https://www.ebay.com/itm/Corning-Glass-memory-/125087612899
>
> I can't find any info on it - was it some kind of delay-line or magnetic
> laminate stack?
>
> Interesting!
Very interesting - there
On 2022-Mar-31, at 4:12 PM, Noel Chiappa wrote:
>> From: Brent Hilpert
>
>> So apparently I've been looking at the wrong +5V supply (H777) because
>> the rest of you are indeed looking at a different +5 supply (H7140),
>> both of which are in that same 11/24 pdf d
On 2022-Mar-31, at 2:14 PM, Rob Jarratt wrote:
>> Those three comparators in the H777 are looking at a time-delay ramp
>
> Is that a typo? This is the H7140 not the H777.
Groan.
When this thread came up I went looking for the 11/24 schematic. I found the
document I linked earlier for the 11/24
On 2022-Mar-31, at 12:36 AM, Noel Chiappa via cctalk wrote:
>> From: Tony Duell
>
>> A short in FET Q15 on the bias/interface board in the PSU could do it.
>> The gate of that FET is driven from an LM339 comparator the -ve supply
>> of which is -15V.
>
> Ah; I hadn't even looked at the P/S
On 2022-Mar-28, at 4:07 PM, Noel Chiappa via cctalk wrote:
>> I don't think the CPU is working at all. The reason being that there is
>> absolutely no LED activity. Including an LED that is supposed to indicate
>> a clock.
>
> Looking at the KDF11-U prints, I finally found that LED (it's pretty
On 2022-Mar-18, at 1:31 AM, Christian Corti via cctalk wrote:
> On Thu, 17 Mar 2022, Brent Hilpert wrote:
>> Does anyone have or know whether the schematics for the IBM 5110 or 5100 are
>> available?
>
> No, there are no schematics, only block diagrams. I had crea
On 2022-Mar-17, at 8:56 PM, D. Resor wrote:
> It looks as if it needs at least a replacement CRT. From one image it
> appears to be phosphor is blown away in the middle screen. The only way I
> know of this happening, is the neck of the CRT, or the evacuation nipple has
> been cracked/broken.
On 2022-Mar-17, at 9:09 PM, Guy Sotomayor via cctalk wrote:
> But it has APL (you can tell by the keyboard *and* the BASIC/APL switch).
>
> I can't say if the price is worth it for that...but having the APL ROS and
> the keytops has some value.
Yes, that is the particular interest in this
On 2022-Mar-17, at 5:02 PM, D. Resor via cctalk wrote:
> Was the computer auction in question a 5100 or a 5110?
>
> Presently I see there is a 5110-C for sale
> https://www.ebay.com/itm/294865912729
Yes, that was/is the one. So it has been relisted. It had been listed as a 5100
or 5100-C
Does anyone have or know whether the schematics for the IBM 5110 or 5100 are
available?
And the tightly related question of whether anyone has done ROM (ROS) dumps?
There are some service manuals on bitsavers, they are field-service board-level
manuals, mostly step-by-step problem resolution
On 2022-Feb-24, at 11:32 AM, Paul Berger via cctalk wrote:
> On 2022-02-24 14:16, Brent Hilpert via cctalk wrote:
>> On 2022-Feb-24, at 8:29 AM, Clemar Folly via cctalk wrote:
>>> I'm looking for information about Texas Instruments TB-759933 IC.
>>>
>>> Does an
On 2022-Feb-24, at 8:29 AM, Clemar Folly via cctalk wrote:
>
> I'm looking for information about Texas Instruments TB-759933 IC.
>
> Does anyone have the datasheet or any other information about this IC?
A search shows this question was posted over here, with a picture:
On 2022-Feb-17, at 11:40 PM, Rob Jarratt wrote:
>> -Original Message-
>> From: Brent Hilpert
>> On 2022-Feb-17, at 2:38 PM, Rob Jarratt wrote:
>>>> -Original Message-
>>>> From: Brent Hilpert
>>>>
&
On 2022-Feb-17, at 2:38 PM, Rob Jarratt wrote:
>> -Original Message-
>> From: Brent Hilpert
>>
>> 20V on a 10 ohm load: current = 2A.
>> 15V, 1.5A.
>>
>> In this regulator design there is no path for more current than that which
>> the
&
On 2022-Feb-13, at 9:04 AM, Douglas Taylor via cctalk wrote:
> Stopped fooling with the AXV11 for now. Applied various voltages to the Data
> Translation input and recorded the A/D octal values to get an idea of what
> the calibration of the board is. It looks very linear, +/-10v range.
>
>
On 2022-Feb-10, at 9:50 PM, Chuck Guzis via cctalk wrote:
> I've got a piece of gear here with a bad MC858P used as a bus
> driver--terminated in 220/330 ohms at the far end.
>
> Given that old DTL is a hit-or-miss proposition, I'm proposing to
> substitute a 7438 OC buffer. Pinout's the same,
On 2022-Jan-26, at 3:41 PM, Rob Jarratt via cctalk wrote:
> I am trying to test a couple of H745 regulators with a DC bench PSU and I am
> having some problems with testing them.
>
> My bench PSU is a twin unit so I can supply the +15V required as well as the
> "AC" input using 20VDC from the
On 2022-Jan-06, at 4:04 PM, Matt Burke via cctalk wrote:
> On 06/01/2022 12:59, Jonathan Chapman via cctalk wrote:
>> That said, it's not like replacing them with new will *hurt* -- it just
>> might not fix the whine.
>
> I suspect that it won't fix the problem. Slightly hijacking the thread
>
On 2022-Jan-06, at 12:19 AM, Joshua Rice via cctech wrote:
> Not cost effective at nearly $10,000! I understand they're very rare, given
> they were only used for a few years in industry and they're clocking on 3/4
> of a century old, but even then, that seems an order of magnitude or two off
>
On 2022-Jan-06, at 12:19 AM, Joshua Rice via cctech wrote:
> Not cost effective at nearly $10,000! I understand they're very rare, given
> they were only used for a few years in industry and they're clocking on 3/4
> of a century old, but even then, that seems an order of magnitude or two off
>
On 2021-Nov-27, at 11:22 AM, Gregory Beat via cctalk wrote:
>
> The Texas Instruments (TI) 139 is likely a 2N139 PNP (BJT) transistor,
> capable of high speed switching (in that era).
>
> The 2N139 was originally an RCA transistor (tall cylinder) found in RCA and
> GE transistor radios (455
On 2021-Nov-26, at 1:52 PM, Al via cctalk wrote:
> A while ago I received an IBM 3286 printer, annoyingly some of the
> transistors in the printer section have been corroded. What I am having
> trouble with is reading the part codes and finding a modern equivalent of
> them.
> There are two
On 2021-Sep-27, at 10:52 AM, Brent Hilpert via cctalk wrote:
> On 2021-Sep-27, at 8:23 AM, Tom Hunter via cctalk wrote:
>> While restoring and repairing a Data General Nova 2/10 I found a bad
>> bipolar PROM on the CPU board. The PROM has open-collector outputs and is
>> organ
On 2021-Sep-27, at 8:23 AM, Tom Hunter via cctalk wrote:
> While restoring and repairing a Data General Nova 2/10 I found a bad
> bipolar PROM on the CPU board. The PROM has open-collector outputs and is
> organized as 32 words by 8 bits. It appears that one of the open-collector
> driver
On 2021-Jul-24, at 2:36 AM, DI Gerhard Kreuzer via cctalk wrote:
> I own a Pro-Log M980 Prom Programmer and want to program a 2732 EProm. I
> have everything needed, but how can I get the data in?
> There is a serial interface, did anybody have some program for a standard
> PC to handle that daa
On 2021-Jul-20, at 4:04 PM, Jules Richardson via cctech wrote:
> On 7/20/21 12:13 PM, pspan via cctech wrote:
>> I worked at a company called DMA located in Amery Wisconsin during the 80's
>> and 90's that did do core mat repair. Yes, the gal that did the work used a
>> scope. She replaced cores
On 2021-Jun-26, at 10:15 AM, Paul Koning via cctalk wrote:
>> On Jun 26, 2021, at 11:31 AM, Tapley, Mark B. via cctalk
>> wrote:
>>
>> At one point FTDI had a reasonably good reputation, and I own one of those
>> devices based on that reputation. I have used it with no obvious problems
>>
This is funny, as everyone (me too) weighs in with their description of the
elephant.
My recollection (also from recent observation of a VT278):
- case main: very light cream, somehow with a touch of grey, but not
pure white
- case insets: very dark brown
Remember, it was the
On 2021-Jun-20, at 7:38 PM, ben via cctech wrote:
> On 2021-06-20 8:13 p.m., Toby Thain via cctech wrote:
>
>> Tried the Shunting Yard algorithm? But watch out, it was invented by a
>> quiche eater...
>
> The problem needs backtracking to generate correct code. Stack or
> muilti-register
On 2021-Jun-20, at 9:19 PM, ben via cctalk wrote:
> On 2021-06-20 9:01 p.m., Brent Hilpert via cctalk wrote:
>> On 2021-Jun-20, at 7:38 PM, ben via cctech wrote:
>>> On 2021-06-20 8:13 p.m., Toby Thain via cctech wrote:
>>>
>>>> Tried the Shunting Yard al
On 2021-May-29, at 7:58 AM, William Donzelli via cctalk wrote:
> Over on the Discord, I have posted a DEC Computer Lab H-500 for sale.
> Needs cosmetic help, but will be priced accordingly.
>
> Offers? Off list...
As I am aware of it Discord is a software package.
What does "Over on the
On 2021-May-09, at 2:16 PM, David Williams via cctalk wrote:
> Working on restoring my very first computer, an Apple II+. Got it mostly
> working with just a couple of issues identified at the moment. Some of the
> keys on the keyboard don't register but I can work on that. The real question
>
On 2021-May-04, at 4:06 PM, Donald via cctalk wrote:
> In the deep recesses of my mind I seem to remember something about S/360
> machines using a motor generator.
>
> If I am right was this to create a stable power source at a certain
> frequency or voltage?
I dont know about the 360, but a
On 2021-Apr-24, at 12:43 PM, David Williams via cctalk wrote:
> Moving forward on setting up my collection and I was taking a look at an
> Exidy Sorcerer S-100 Expansion box I had received long ago. I wondered if
> anyone could help with info on the cards I found inside. The first is clearly
>
On 2021-Apr-21, at 1:49 AM, Christian Corti via cctalk wrote:
> I'm trying to find out if the BASIC dialect that was available for the MINCAL
> computers (aboutn 1971) was something derived from another "system" or
> whether it was an own dialect.
>
> Some characteristic instructions that I
On 2021-Mar-25, at 5:21 PM, Chris Zach via cctalk wrote:
> Well, if there is no cost to asking that amount, why not? It's an
> inefficiency of Ebay that things can stay up there for years, but that is as
> it is.
It's been enough years I don't remember when I first saw it, this has been
listed
On 2021-Feb-23, at 1:45 PM, Frank Tuccio via cctech wrote:
> On 02/22/2021 01:31 PM, Brad H via cctalk wrote:
>>
>> A longshot I'm sure - but I am wondering if anyone familiar with MSI
> (Midwest Scentific - SS50 bus system) would happen to have a copy of the
> software for their 1702A EPROM
On 2021-Feb-12, at 6:08 AM, Paul Koning via cctalk wrote:
>> On Feb 12, 2021, at 7:50 AM, Jules Richardson via cctalk
>> wrote:
>>
>> Hopefully the following link works, but someone over on one of the Facebook
>> vintage groups has this oddball terminal from 1973 that they've been looking
>>
On 2020-Dec-15, at 11:15 AM, Jules Richardson via cctalk wrote:
> On 12/14/20 10:06 PM, Brent Hilpert via cctalk wrote:
>>> (It's definitely -12V, not -5V? I'm just thinking that the -12V noted
>>> on your schematic is quite close the the 15V rating on the cap -
>>> a
On 2020-Dec-14, at 7:57 AM, Jules Richardson wrote:
> On 12/14/20 4:41 AM, Brent Hilpert via cctalk wrote:
>>
>> Yes. Coincidentally I've just been refurbishing one - a Teleray 3931.
>> It's an ASCII/APL terminal, overstriking was included for the APL mode.
>> http
On 2020-Dec-14, at 6:28 AM, Paul Koning wrote:
>> On Dec 14, 2020, at 9:26 AM, emanuel stiebler via cctalk
>> wrote:
>> On 2020-12-14 05:41, Brent Hilpert via cctalk wrote:
>>> On 2020-Dec-14, at 1:26 AM, ben via cctalk wrote:
>>>> Often for data inp
On 2020-Dec-14, at 1:26 AM, ben via cctalk wrote:
> Often for data input one could use over strike characters for input. Not EQ
> might be = BS | Did any video display terminals
> repeat the same effect?
Yes. Coincidentally I've just been refurbishing one - a Teleray 3931.
It's an ASCII/APL
On 2020-Dec-13, at 6:37 PM, Stan Sieler via cctalk wrote:
> ...
> When was the concept of memory "above" the screen invented for terminals?
>
> I.e., previously displayed data that had scrolled up and off the screen ...
> but could be retrieved (usually by scrolling down).
>
> (Sometimes
On 2020-Oct-04, at 1:55 PM, Chris Hanson wrote:
> On Oct 4, 2020, at 1:53 PM, Brent Hilpert wrote:
>>
>>> For the latter two, I need to figure out whether my backplane supports ABCD
>>> use in the first couple of slots, or if it’s purely an ABAB model. (The
>>
On 2020-Oct-04, at 1:14 PM, Chris Hanson via cctalk wrote:
> Thanks to everyone who replied, on- and off-list! There’s an MXV11-B (M7195)
> on its way to me. :)
>
> Since people were asking about my setup, here’s what I have:
>
> - MDB BA11-clone enclosure, PSU, and 8-slot 22-bit backplane
>
On 2020-Oct-04, at 1:22 AM, Josh Dersch via cctalk wrote:
> More mysteries while poking at the MDP-1000. Spent some time this evening
> working out the rest of the signals on the power harness (I suspect inputs
> for an LTC circuit and a "power good" signal, as well as something
> connected to a
On 2020-Oct-01, at 2:03 PM, Paul Koning via cctalk wrote:
>> On Oct 1, 2020, at 1:20 PM, dwight via cctech wrote:
>>
>> It is going to need a lot of contact cleaning.
>> The one thing I like is the carry design the Zuse used. Really fast for
>> relays but not of much use for solid state.
>>
On 2020-Aug-03, at 12:34 PM, John Foust via cctalk wrote:
> At 12:56 PM 8/3/2020, Nick England wrote:
>> Looks interesting - I know nothing more
>>
On 2020-Jul-28, at 6:40 PM, Jay Jaeger via cctech wrote:
> On 7/28/2020 1:43 PM, Brent Hilpert via cctech wrote:
>>
>> Per the OP's machine, the early HP21xx machines were based on CTµL, for
>> which the main supply is +4.5V.
>> DTL and TTL chips in these machi
On 2020-Jul-28, at 4:48 PM, Carlos E Murillo-Sanchez via cctalk wrote:
>
> So, what would two chips marked
>
> F U6A7709393
> 7043
F : Fairchild
U : monolithic device (as opposed to e.g. hybrid)
6A : package, DIP (6), 14-pin (A)
7709: circuit/function code. As Jay suggests, a 709 op
Fairchild part numbers trivia following.
On 2020-Jul-28, at 7:35 AM, Jay Jaeger via cctalk wrote:
> My DTL chips have markings like:
>
> DT uL93659 (Chip type 936)
> F 7016
>
> DT uL909759 (Chip type 9097)
> F 7013
>
> (I expect 7016 and 7013 are date codes. Not sure what the "59" is
On 2020-Jul-10, at 11:27 AM, Ian Finder via cctalk wrote:
> On Fri, Jul 10, 2020 at 11:06 AM Al Kossow via cctalk
> wrote:
>>
>> Since it isn't very fancy, I wonder if you could make a new board with a
>> modern Hall
>> effect sensor? You just need a contact closure.
> Yeah Al, that's a great
On 2020-Jul-09, at 10:12 PM, Ian Finder wrote:
>> On Jul 9, 2020, at 21:58, Brent Hilpert wrote:
>> On 2020-Jul-09, at 9:39 PM, Ian Finder via cctalk wrote:
>>
>>> I know what you guys are thinking- no, this isn't for a keyboard collection
>>> or some mode
On 2020-Jul-09, at 9:39 PM, Ian Finder via cctalk wrote:
> I know what you guys are thinking- no, this isn't for a keyboard collection
> or some modern build or some other nonsense like that.
>
> I have a friend who is restoring a fairly interesting and historically
> significant vintage
On 2020-Jun-09, at 6:21 AM, Shoppa, Tim via cctalk wrote:
> I think a Stanford AI lab has one in a display case. Any others out there?
>
> It was supposedly "commercial" but I don't even remember ever seeing an ad
> for the Cyclops from Cromemco and I had a really good stash of Cromemco
>
On 2020-Jun-07, at 8:30 AM, Noel Chiappa via cctalk wrote:
> Love the title on this:
>
> https://www.ebay.com/itm/184317705963
>
> eBait auction: "16K Sense Inhibit Board .. VAX 6000, VAX-11/730".
> Yeah, core on a VAX! And such a deal, a mere US$400!
To add to the weirdness, here are some
On 2020-May-09, at 9:32 AM, Rob Jarratt via cctalk wrote:
> I have recently been trying to improve the ripple on the output of my
> MicroVAX 3100 Model 95 PSU because occasionally it would fry a memory
> module. I replaced a bunch of capacitors, some of which had started to leak.
> However, the
On 2020-May-04, at 8:10 PM, Martin Crockett via cctalk wrote:
> ..
> I noticed there is a capacitor that has vaporized, but I cant determine
> what value it is.
>
> I have the DEC VT-100 maintenance guide but it is very blurry in the
> relevant area.
>
> I cant even read the board designation.
>
On 2020-Apr-26, at 4:33 PM, Chris Zach via cctalk wrote:
> Latest pictures are at https://www.crystel.com/bob .
https://www.crystel.com/bob/DSC_0255.JPG
HP 9825 (the ochre keyboard) underneath the PCB.
On 2020-Apr-21, at 8:35 PM, Chris Zach wrote:
>> The D8 5V ref and the targetted output V are divided via R15 and R17,R18 to
>> provide the sense input at E2.2.
>> If one does the R ratio of the three resistors, it comes out, as would be
>> expected, to ~ 0V.
>
> Ah hah, that is clever. I
On 2020-Apr-21, at 5:27 PM, Chris Zach via cctalk wrote:
> Meantime reading the manual I found an interesting test: If you short emitter
> to base on Q4 (easiest way is to jumper diode D10) the voltage on the -12v
> supply goes to .4 volts. They're saying it's E2, R15,R17,R14.
>
> Is there a
On 2020-Apr-21, at 7:57 AM, Chris Zach via cctalk wrote:
> Well I'm starting to walk through this. First I took an IR picture of the
> boards in operation, then started troubleshooting.
>
> First I started checking voltages. J2 is easily accessible so I put a ground
> probe on pin 10, and
On 2020-Apr-19, at 3:09 PM, Chris Zach via cctalk wrote:
>> As I wrote earlier in the thread I think it is a good idea to check the V
>> sync and H sync signals to check that they are right in pulse length and
>> shape.
>
> Good starting point. From the schematics would that be scope probe to
On 2020-Apr-18, at 10:03 AM, Rob Jarratt via cctalk wrote:
> I have another PSU I have been meaning to look at for a long time. This one
> has fairly high output ripple and some of the voltages do not appear to be
> where they should be. I have checked all the capacitors for ESR and they
> appear
On 2020-Apr-15, at 5:23 PM, Chris Zach via cctalk wrote:
> Wonderful: A few weeks ago I forgot to turn off my VT52 and left it running
> for a day or two. Now the screen is filled with snow and it looks like the
> text is all over the place horozontally.
>
> Any tips or thoughts on where to
On 2020-Apr-05, at 11:12 PM, Rob Jarratt wrote:
>>
>>> I have obtained a scope trace as you suggest. R32 is still lifted so
>>> the
>>> UC3842 is powered by the bench PSU, but I am using the full 240VAC (no
>>> variac). The channels are:
>>> 1. Ch1. 555 timer.
>>> 2. Ch2. D19 Anode
>>> 3. Ch3.
Here in Canada, ongoing for several years now, we've had the major fiasco of
the Phoenix payroll system.
I've never heard an accounting of where the fault lies, or why IBM isn't being
held more accountable.
A brief summary from Wikipedia:
The Phoenix pay system is a payroll processing system
On 2020-Apr-05, at 2:53 PM, Rob Jarratt wrote:
> I have obtained a scope trace as you suggest. R32 is still lifted so the
> UC3842 is powered by the bench PSU, but I am using the full 240VAC (no
> variac). The channels are:
> 1.Ch1. 555 timer.
> 2.Ch2. D19 Anode
> 3.Ch3. D19 Gate.
> 4.
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