The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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A refefernce to 6502 by “Remember that in a stack trace, the addresses are return addresses, not call addresses – The Old New Thing”

Posted by jpluimers on 2018/09/11

On x86/x64/ARM/…:

It’s where the function is going to return to, not where it came from.

And:

Bonus chatter: This reminds me of a quirk of the 6502 processor: When it pushed the return address onto the stack, it actually pushed the return address minus one. This is an artifact of the way the 6502 is implemented, but it results in the nice feature that the stack trace gives you the line number of the call instruction.

Of course, this is all hypothetical, because 6502 debuggers didn’t have fancy features like stack traces or line numbers.

Source: [WayBack] Remember that in a stack trace, the addresses are return addresses, not call addresses – The Old New Thing

Which resulted in these comments at [WayBack] CC +mos6502 – Jeroen Wiert Pluimers – Google+:

  • mos6502: And don’t forget the crucial difference in PC on 6502 between RTS and RTI!
  • Jeroen Wiert Pluimers: +mos6502 I totally forgot about that one. Thanks for reminding me
    <<Note that unlike RTS, the return address on the stack is the actual address rather than the address-1.>>

References:

[WayBack] 6502.org: Tutorials and Aids – RTI

RTI retrieves the Processor Status Word (flags) and the Program Counter from the stack in that order (interrupts push the PC first and then the PSW).

Note that unlike RTS, the return address on the stack is the actual address rather than the address-1.

[WayBack] 6502.org: Tutorials and Aids – RTS

RTS pulls the top two bytes off the stack (low byte first) and transfers program control to that address+1. It is used, as expected, to exit a subroutine invoked via JSR which pushed the address-1.

RTS is frequently used to implement a jump table where addresses-1 are pushed onto the stack and accessed via RTS eg. to access the second of four routines.

–jeroen

Posted in 6502, 6502 Assembly, Assembly Language, Development, History, Software Development, The Old New Thing, Windows Development, x64, x86 | Leave a Comment »

Spelling with element symbols from the Periodic table

Posted by jpluimers on 2018/09/11

The [WayBack] Periodic table – Wikipedia contains many symbols.

Combing them allows you to spell word. Not all words, but many of them can be spelled.

So I was glad finding the below article that started with the same fascination I had in chemistry class.

[WayBack] Spelling with Elemental Symbols

It has a great explanation of the algorithm, references to computer science literature and a nice Python implementation.

via: [WayBack] One of the best programming articles I’ve read in a while – This is why I Code – Google+

–jeroen

Read the rest of this entry »

Posted in Algorithms, Development, Fun, LifeHacker, Power User, Python, science, Scripting, Software Development | Leave a Comment »

DFRobot 7″ HDMI Display with Touchscreen Sells for $69 – for use with Raspberry Pi or Adruino

Posted by jpluimers on 2018/09/10

There are plenty of HDMI displays, but if you want a smaller size it become more complicated although some 7″ HDMI displays are available. However, if you

Source: [Archive.is] DFRobot 7″ HDMI Display with Touchscreen Sells for $69

Via: [Archive.is] 7″ HDMI touchscreen display with mounting holes for +Raspberry Pi board. – Jean-Luc Aufranc – Google+

–jeroen

Posted in Development, Hardware Development, Power User, Raspberry Pi | Leave a Comment »

Notifications – Google+

Posted by jpluimers on 2018/09/10

For mu own memory: Notifications – Google+ are at https://plus.google.com/notifications/all

–jeroen

 

Posted in G+: GooglePlus, LifeHacker, Power User, SocialMedia | Leave a Comment »

Nooit toestemming gegeven, toch in het EPD? Check het zelf! | Platform Bescherming Burgerrechten

Posted by jpluimers on 2018/09/10

[WayBack] Nooit toestemming gegeven, toch in het EPD? Check het zelf! | Platform Bescherming Burgerrechten:

Burgers ontdekken dat hun medische gegevens in het systeem staan en door verschillende partijen zijn geraadpleegd, zonder dat ze daar ooit toestemming voor gaven. De enige manier om zeker te weten dat je dossier niet via het systeem beschikbaar wordt gesteld, is door dit zelf na te vragen.

–jeroen

Posted in LifeHacker, Power User, Privacy | Leave a Comment »

MUSTOOL MT8206 Multimeter & Oscilloscope Goes for $42 (Promo)

Posted by jpluimers on 2018/09/09

The coupon for the Promo worked yesterday, so you might want to try it if you like a scope in a multimeter form factor: [WayBack] MUSTOOL MT8206 Multimeter & Oscilloscope Goes for $42 (Promo).

MUSTOOL MT8206 looks like a standard digital multimeter, but the device is actually a 2-in-1 device that also serves as a oscilloscope. Banggood have the…

Via [WayBack] New 2-in-1 digital multimeter + oscilloscope selling for ~$42 shipped for a limited time – Jean-Luc Aufranc – Google+

–jeroen

Posted in Development, Hardware Development, Power User | Leave a Comment »

Happy testers day.

Posted by jpluimers on 2018/09/09

Fitting for a day like this.

[WayBack] Testing: Hammering Nails via [WayBack] Testing: Hammering Nails – This is why I Code – Google+

Posted in Fun, Testing | Leave a Comment »

https://altd.embarcadero.com/ TLS certificate does not match domain name

Posted by jpluimers on 2018/09/07

One of the domains not yet monitored at embarcaderomonitoring.wiert.me, was the altd download server for ISOs and installers on http and https level. Ultimately you want https, as most of these are about installers, so you do not want any man-in-the-middle to fiddle with them.

TLS on altd fails

Upitmerobot is not yet smart enough to check validity of TLS certificates on https connections.

Chrome, Firefox, Safari, Internet Explorer, wget, curl and ssllabs however are.

altd hides as much from itself as possible

Uptimerobot did not like monitoring the plain http://altd.embarcadero.com/ and https://altd.embarcadero.com/ URLs, because the altd is not browsable, so it tries to hide most of its structure from access. This means they both return an odd response:

Those responses are actually 404 errors (note the - minus sign after curl --trace-ascii: it sends the trace to stdout):

$ wget http://altd.embarcadero.com/
--2018-09-05 10:44:23-- http://altd.embarcadero.com/
Resolving altd.embarcadero.com (altd.embarcadero.com)... 88.221.144.40, 88.221.144.10
Connecting to altd.embarcadero.com (altd.embarcadero.com)|88.221.144.40|:80... connected.
HTTP request sent, awaiting response... 404 Not Found
2018-09-05 10:44:23 ERROR 404: Not Found.

$ curl --verbose http://altd.embarcadero.com/
*   Trying 88.221.144.40...
* TCP_NODELAY set
* Connected to altd.embarcadero.com (88.221.144.40) port 80 (#0)
> GET / HTTP/1.1
> Host: altd.embarcadero.com
> User-Agent: curl/7.54.0
> Accept: */*
> 
< HTTP/1.1 404 Not Found
< Server: Apache
< Content-Type: text/html; charset=iso-8859-1
< Content-Length: 16
< Date: Wed, 05 Sep 2018 08:45:57 GMT
< Connection: keep-alive
< 
* Connection #0 to host altd.embarcadero.com left intact
File not found."

$ curl --trace-ascii - http://altd.embarcadero.com/
== Info:   Trying 88.221.144.40...
== Info: TCP_NODELAY set
== Info: Connected to altd.embarcadero.com (88.221.144.40) port 80 (#0)
=> Send header, 84 bytes (0x54)
0000: GET / HTTP/1.1
0010: Host: altd.embarcadero.com
002c: User-Agent: curl/7.54.0
0045: Accept: */*
0052: 
<= Recv header, 24 bytes (0x18)
0000: HTTP/1.1 404 Not Found
<= Recv header, 16 bytes (0x10)
0000: Server: Apache
<= Recv header, 45 bytes (0x2d)
0000: Content-Type: text/html; charset=iso-8859-1
<= Recv header, 20 bytes (0x14)
0000: Content-Length: 16
<= Recv header, 37 bytes (0x25)
0000: Date: Wed, 05 Sep 2018 08:47:19 GMT
<= Recv header, 24 bytes (0x18)
0000: Connection: keep-alive
<= Recv header, 2 bytes (0x2)
0000: 
<= Recv data, 16 bytes (0x10)
0000: File not found."
File not found."== Info: Connection #0 to host altd.embarcadero.com left intact

This is also the reason that WayBack does not want to archive that link, but it can be archived at [Archive.is] https://altd.embarcadero.com/.

Luckily, a Google search for site:altd.embarcadero.com revealed there is a non-installer file short enough (~72 kibibytes) for Uptime robot to check, so it now verifies it can access these:

–jeroen

Read the rest of this entry »

Posted in *nix, *nix-tools, cURL, Encryption, HTTPS/TLS security, Monitoring, Power User, Security, Uptimerobot, wget | Leave a Comment »

God is real unless declared integer, 

Posted by jpluimers on 2018/09/07

Kristian Köhntopp commended:

GOD IS REAL UNLESS DECLARED INTEGER..

In some versions of Fortran, the default type of variables starting with I, J, K or L is integer, while other varianles are by default typed as real. The Fortran statement DECLARE can be used to explicitly declare a variables as being of a specific type.

The variable GOD stats with G and hence is implicitly real, unless you add an appropriate declare statement.

He reminded my of my FORTRAN 66 days at university when studying “computer usage for chemists”:

I remember a “computer usage for chemists” course during my studies where (end of the 1980s!) were supposed to program in FORTRAN 66.
Luckily the VAX/VMS machine supported a much more recent FORTRAN version and had support for 132 columns as well, which allowed me to indent properly (like I was used from my Pascal background).This tremendously helped me solve basically this problem:

  • import tables with
    1. atom code, radius and valence (bonding count)
    2. atom1 code, atom2 code, minimum distance, maximum distance
    3. atom code, X/Y/Z coordinate
  • determine which bonds can occur
  • walk the bonds and determine the atomic structure, including cycle count

Especially the last one was easiest to solve with recursion, which FORTRAN does not support. So I wrote my own stack structure and solved the problem.

The student coach was mad when she found out I had printed the full documentation on continuous form paper which took the printer about half an hour for printing the ~100 pages.

Next morning, I had read it front-to-back and colour-indexed all the sections so it was far easier to find what the compiler could do for me. She could not believe I had done that.

All my co students were on a (non shielded!) 300 meter multiplexed serial connection with VT-120 emulators from PC’s with all sorts of connection problems.

I discovered a small room right above the VAX/VMS machine having a couple of terminals with direct connections that were hardly used. A few of them were VT-240 that had a session switch allowing for maximum 3 interactive sessions running at far higher priority than the compiler/linker batch queues provided.

This allowed me to perform quick release cycles of my project: 1 session for editing and inspecting logs, 1 session for compiling my last version, 1 session for linking the previously compiled version.

I was about the only student that delivered the project on time (:

Via: Archive.is Check out @chicaScientific’s Tweet: https://twitter.com/chicaScientific/statu… having

“Why did the integer drown?”

“Because he wasn’t a float”

–jeroen

 

Posted in Fun, History, Quotes, T-Shirt quotes | Leave a Comment »

LiFePO4wered/Pi+ | Crowd Supply

Posted by jpluimers on 2018/09/07

A few days left for [WayBack] LiFePO4wered/Pi+ | Crowd Supply: A full-featured LiFePO4 battery, power manager, and UPS for the Raspberry Pi

via:

–jeroen

 

 

Posted in Development, Hardware Development, Power User, Raspberry Pi | Leave a Comment »

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