Category Archives: Software

unintentional nondeterminism in a Python program

There’s a Python 3 program I’ve been developing off-and-on for three years now. The program takes an XML file as input, does some processing, and outputs a binary file.  After some recent changes, I find that the program hangs. If … Continue reading

Posted in Computing, Software | Leave a comment

Creating bootable USB media from ISO image

I’ve found lots of reverences to using livecd-iso-to-disk from the livecd-tools package to create bootable USB media from an ISO image (or for a DVD, quite possibly a UDF image, but the principle is the same). However, most of the … Continue reading

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TRS-DOS as possible prior art for MS patent on exFAT, and reference request

Microsoft introduced a new “exFAT” file system a few years ago, and I wouldn’t care about it in the least, except that it is now the official filesystem for SD-XC cards.  I only care about that in that digital cameras … Continue reading

Posted in Patents, Retrocomputing, Software | 3 Comments

Building EPEL6 packages that use Qt 4

I’ve been trying to build an EPEL 6 package (for Red Hat Enterprise Linux 6, Centos 6, etc.) of Meshlab, for which I already have a Fedora package.  The latest challenge is that the Koji build server is trying to … Continue reading

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Linux group management

The conventional wisdom has it that if you add a user to a group in a Linux (or Unix) system, the user will have to log in again for the new group membership to take effect.  Using the “newgrp” command, … Continue reading

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TRS-80 Model II TRSDOS: paranoia strikes deep

It looks like the developers of TRS-80 Model II TRSDOS were very paranoid that someone might be able to bypass the filesystem and access data on a floppy directly.  I’m not sure if their primary concern was file password protection, … Continue reading

Posted in Retrocomputing, Reverse-engineering, Software | Leave a comment

Code to encode and decode Kansas City standard

As part of my Retrochallenge 2012WW project, I’m writing a pair of C programs to encode and decode Kansas City standard and Processor Technology CUTS audio cassette formats, as these are the formats supported on the Processor Technology Sol-20.  These … Continue reading

Posted in RetroChallenge, Software | 5 Comments

C programming, the suboptimal way

Never name a C function read(), unless you’re trying to replace the system read() function.  Maybe not a problem on Windows, I’m not sure, but definitely bad news on Unix or Linux. I spent over an hour trying to figure … Continue reading

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More progress to report, after all

I fixed several bugs in my code, and now the DIY4 can display the directory of an SD card and read and write files. It’s not perfect, as the first I/O fails, but subsequent accesses succeed. I’m using the open … Continue reading

Posted in Calculators, Hardware, RetroChallenge, Software | Leave a comment

Display contrast in DIY4

The DIYRPN 4 calculator uses a 16×2 character LCD module. The choice of module was limited due to the desired physical width of the calculator. We chose a module made by Lumex. The module is specified for operation on a … Continue reading

Posted in Calculators, Hardware, RetroChallenge, Software | Leave a comment