Category Archives: Software

Code to encode and decode Kansas City standard

Posted on January 2, 2012 by Eric

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 | Leave a comment

C programming, the suboptimal way

Posted on January 2, 2012 by Eric

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 →

Posted in RetroChallenge, Software, The Suboptimal Way | Leave a comment

More progress to report, after all

Posted on July 31, 2011 by Eric

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

Posted on July 26, 2011 by Eric

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

Keyboard scanning on the DIY4

Posted on July 25, 2011 by Eric

I tracked down a bug in the keyboard scanning of the DIY4 today. I thought there needed to be a delay in the scan routine between writing the scan lines and reading the return lines, but it turns out that … Continue reading →

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

Bit-banging FRAM on the DIYRPN 4

Posted on July 25, 2011 by Eric

I’ve written code that successfully reads the vendor/device ID and serial number from a Ramtron FM25VN10 SPI FRAM chip. I haven’t yet read or written data. The code is currently using GPIO bit-banging, but the hardware is designed to allow … Continue reading →

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

HP-41 card reader bug

Posted on July 25, 2011 by Eric

It occurred to me while studying simulator traces that it might be interesting to investigate a bug in early versions of the 82104A card reader for the HP-41C calculator. The bug was fairly esoteric and easily avoided, as it seemed … Continue reading →

Posted in Calculators, Nonpareil, RetroChallenge | Leave a comment

HP-41CV ROM set version HFF bug fix

Posted on July 25, 2011 by Eric

As I was studying HP-41CV microcode running in simulation, I finally uncovered what one of the bug fixes in the HFF ROM version does. This has been a mystery for many years, though there’s still one more unexplained change relative … Continue reading →

Posted in Calculators, Nonpareil, RetroChallenge | Leave a comment

misc. hints on debugging Linux power management

Posted on June 8, 2011 by Eric

Dump BIOS DMI table: dmidecode Dump devkit power status:  devkit-power –dump or upower –dump Enable power manager debugging, useful before suspend:  echo 1 >/sys/power/pm_trace look at log file: /var/log/pm-suspend.log

Posted in Fedora, Linux | Leave a comment

misc. Linux notes

Posted on June 8, 2011 by Eric

Things I’ve learned today that I’ll probably need to know later, after I’ve had a chance to forget them: GNOME 3 was designed by idiots for idiots.  They’ve tried to make it completely drool-proof, and in the process made it … Continue reading →

Posted in Fedora, Linux | 1 Comment