MS Word will break your links!

I was pleased to see that my nerrrdy Bourgoin mini-zine got cited in an art workbook for schools: Islamic mosaics activity (Patterning) from MathWeave. Yay!

But the link in the workbook doesn’t work! I mean, it looks right:

While the real link is:

Only when you copy the bad URL do you see the problem:

http://scruss.com/blog/2016/07/21/nerrrdy%E2%80%90bourgoin%E2%80%90mini%E2%80%90zine/

Word has changed the pasted ‘-’s to ‘‐’s: that’s from U+002D HYPHEN-MINUS to U+2010 HYPHEN. You’d have thought that software that was smart enough to recognize an URL would also be smart enough not to do any messing with the characters in it …

Most of the Logic Apple II Library now on archive.org


Well, that’s all the disks I can find easily up on archive.org. There are some Apple IIgs disks still to do, and there might be some random disks lurking in another box, but that’s more than 485 disk images uploaded.

You can find them by going to Internet Archive Search: creator:”LOGIC (“Loyal Ontario Group Interested In Computers”)”.

Installing the Pimoroni OnOff Shim the hard way

Hey! This process permanently modifies your Raspberry Pi and may prevent it from working with many HATs and add-ons … It also has some really fiddly soldering. If in doubt, don’t.

Pimoroni’s OnOff SHIM adds what the Raspberry Pi should have had all along: a power button. While there are lots of soft power switches out there, the OnOff Shim adds circuitry to cut power to the Raspberry Pi after shutdown.

While the shim comes with a 12-socket header, that prevents you from using any other device that uses the leftmost GPIO pins. I wanted access to all the pins, and not have the shim create an unsightly bump on the pins. So this is what I did …

Regular GPIO header in place on a Raspberry Pi Zero W
Test-fit the socket header to mark where you’re going to cut the pin support block
Very carefully, cut the pin support block between (physical) pins 11-13 and 12-14. I used a mix of a sharp craft knife and nibbling with fine diagonal cutters. Try not to bend the GPIO pins either as you cut the block or lever the block out of the way
Apply non-conductive tape to the back of the OnOff Shim. I used Kapton, but electrical/insulating tape will do. Just make sure you don’t block any of the GPIO holes
Test-fit the shim. You may have to pare away at the support block a bit to get it to fit level with the rest of the pins
Now solder the shim in place. You want the solder joints as small as possible. I used extra liquid flux and very fine silver solder to just fill the pin holes. Too much solder left on the pins will stop HATs and socket headers fitting, so you may have to desolder as I had to do on the rightmost pin
Example HAT fitted with OnOff shim underneath. Note that his particular HAT — the Pimoroni Inky pHAT — will not work with this shim.

The OnOff SHIM uses GPIO pin BCM 17 (physical pin 11) as the power button sensor and BCM 4 as the power off signal. Any device that also uses BCM 17 (and possibly BCM 4) will likely cause the reset process to be triggered. This means that I can’t use the shim with my Inky pHAT EPD. You would have thought that Pimoroni might’ve considered that, since they made both. Consulting pinout.xyz suggests that 41 boards that likely may not work with the OnOff shim: Cirrus Logic Audio Card, Display-o-Tron 3000, DOTs, Enviro pHAT, ESP IoT pHAT, Explorer HAT, Explorer HAT Pro, Flex, GertVGA 666, High-Precision AD/DA Board, Hyperpixel, Inky pHAT, IoT pHAT, LEDBorg, MotoZero, Navio2 Autopilot, PaPiRus HAT, PaPiRus Zero, Piano HAT, Pibrella, Picade HAT, Pi Cap, PiGRRL Gamepad, Pi-LITE-r, Pi-mote, Pi PoE Switch HAT, PiStep2 Dual, PiStep2 Quad, Pi Stop, Propeller HAT, RoboHat, RTK Motor Controller, Servo PWM Pi Zero, Skywriter HAT, Ultimate GPS HAT, Voice HAT, Witty Pi, Witty Pi 2, Zero2Go, Zero LiPo and ZeroSeg.

While I like the OnOff SHIM, check carefully that it will work with your application.

Installing the Versatile Commodore Emulator (VICE) on Raspberry Pi

As requested on our local Commodore user group mailing list, how to install VICE on a Raspberry Pi 3 running Raspbian Stretch:

# get dependencies - this may take a long time and ~ 1.5 GB
sudo apt install autoconf automake build-essential byacc dos2unix flex libavcodec-dev libavformat-dev libgtk2.0-cil-dev libgtkglext1-dev libmp3lame-dev libmpg123-dev libpcap-dev libpulse-dev libreadline-dev libswscale-dev libvte-dev libxaw7-dev subversion texi2html texinfo yasm libgtk3.0-cil-dev xa65

mkdir -p src

cd src

svn checkout https://svn.code.sf.net/p/vice-emu/code/trunk trunk

cd trunk/vice

./autogen.sh

./configure

make -j4

sudo make install

This was freely adapted from the build docs, Linux-Native-Howto.txt, which has more info if you get stuck.

6502 badge is go!

Yes readers, I built one:

All of 2 KB RAM, but the form factor can’t be beat. I’m sure I’ll be the hippest cat on the block when I pair it with my happening 2012 Hamvention lanyard …

Thanks to Josh Bensadon for bringing a 6502 40th Anniversary Badge back from VCF Midwest. Josh also got my Apple //e going again by replacing RAM chips: I can’t thank him enough for that, too!

VCF-MW 2017 6502 badge, with almost everything socketed

I did make some minor mods to the build:

  • I socketed the main chips. The 6502 is in 2× cut up 20-pin narrow sockets. Under the EPROM is the 2K×8 SRAM, socketed too. This means that the EPROM is in two stacked sockets and sticks out far too far. But at least it’ll allow me to upgrade the RAM
  • I used real pin-header jumpers and links for RAM and EPROM size selection instead of solder links. This meant a horrible kludge for the RAM selector under the SRAM chip involving angled and bent headers, a filed-down chip socket and a hand-knotted wire jumper (artisanal af!)
  • Even though there’s no mention of it in the manual, I stuck the battery pack on the back
  • One bad mod: the HL-340 RTS mod suggested in the manual is much harder than it looks. I trashed the supplied USB adapter, but I have others …

importing Applesoft BASIC programs on the Apple IIe

Just what no-one has needed since about 1979 or so …

BASIC on the Apple II has no easy way to import text as a program. When you LOAD a file, it must be in Apple’s tokenized format. While Apple DOS has the EXEC facility to run script files as if they were typed from the keyboard, it’s very picky about the file format:

  1. There must be a carriage return character (CR, ASCII 13) before the first line
  2. All line numbers must have an extra space before and after them
  3. All tokens must be in upper case
  4. All tokens (keywords and functions) must have a space after them.

The right way to do this conversion would be to write a tokenizer that spits out the correct binary file. But you can (kinda) fudge it with this shell command, operating from BASIC source PROG.BAS:

sed 's/^[0-9][0-9]*/& /;s/^/ /;1s/^/\n/;s/$/ /;s/[:()]/ & /g;' PROG.BAS | tr '\n' '\r' | ac.sh -p EG.dsk PROG T

ac.sh is the command line version of AppleCommander, and the file EG.dsk referred to above is an Apple DOS 3.3 image created with

ac.sh -dos140 EG.dsk

It still needs work, as there are functions that will mess this up, and Applesoft’s parser makes a mess of code like IF A THEN …, turning it into IF AT HEN ….

So if I wanted to import the following futile program:

10 REM A FUTILE PROGRAM BY SCRUSS
20 HOME
30 FOR X=1 TO 20
40 PRINT SPC(X);"FUTILE"
50 NEXT X

Run through the script (but before EOL conversion) it would look like this:

 10  REM A FUTILE PROGRAM BY SCRUSS 
 20  HOME 
 30  FOR X=1 TO 20 
 40  PRINT SPC ( X ) ;"FUTILE" 
 50  NEXT X

Make a disk and put the modified program text on it:

ac.sh -dos140 futile.dsk
sed 's/^[0-9][0-9]*/& /;s/^/ /;1s/^/\n/;s/$/ /;s/[:()]/ & /g;' futile.bas | tr '\n' '\r' | ac.sh -p futile.dsk FUT T

Load the disk into your Apple II, clear out the init program, and import the code with EXEC FUT:

If all you get is ] cursors printed and no syntax errors, then something might be working. List it:

Run it:

Disk image: futile-AppleII-dsk.zip, containing:

$ ac.sh -l futile.dsk

DISK VOLUME #254
 T 002 FUT 
 A 002 FUTILE 
DOS 3.3 format; 134,144 bytes free; 9,216 bytes used.

The first of many … Logic Apple II library disks

TL;DR Update — The disk images are here: creator:”LOGIC (“Loyal Ontario Group Interested In Computers”)”

The Apple II post from the other day wasn’t as random as it might seem. Through a friend, I got given not just the Apple IIe previously pictured, but also an Apple IIgs and the almost-complete disk library from a local Apple user group.

Logic (“Loyal Ontario Group Interested in Computers”) appears to be defunct now. The Internet Archive has 20+ years of their website logicbbs.org archived, but the domain no longer resolves. It’s a shame if they are completely gone, because user groups contain social history. Once it’s gone, well … never send to know for whom the CtrlG tolls; it tolls for thee.

I’m going to archive as much of the Logic disk library as I can. I’ve been chatting with Jason Scott, and he’s keen to see that the disk images are preserved.

I’d never used an Apple II before. They’re quite, um, different from anything else I’d used. Sometimes hideously low-level (slot numbers!), sometimes rather clever (I/O streams from any of the cards can control the computer). Since nothing but an Apple II can read Apple II disks, I’ve got the IIgs running ADTPro sending images via serial to a Linux machine. It’s pretty quick: a 140 K disk image transfers in around 25 seconds, an 800 K image in just under two minutes. I’m marshalling the images with AppleCommander and trying to keep everything intact despite having little idea what I’m doing.

(Apple II annoyance: searching for the term is harder than it needs to be, as people will try to use the typography of the time and refer to it as “Apple ][”, or “Apple //”. Even though the Unicodely-correct representation should be “Apple Ⅱ”, nobody uses it. I’m going to stick with the two-capital-eyes version ‘cos it’s easier to type.)

Big old scanned manuals to small old scanned manuals

It is good that there are so many scanned manuals for old computer systems out there. Every old system did things its very own special way, and life’s too short to guess. I mean, there’s not much out there on the SYM-1 I’m trying to get working again:

— not much except for 6502.org’s excellent Synertek SYM-1 Resources, that is.

Some manuals, though, while lovingly scanned, are just too large to download, browse or file. Take, for instance, AppleIIScans’ Apple II BASIC Programming With ProDOS. It’s a very faithful colour scan, but at 170 MB for 280 pages, it’s a bit unwieldy. I suspect it’s Adobe Acrobat Paper Capture’s fault: while it makes turning scans into readable files really easy, it doesn’t warn against using 600 dpi full colour for a book with only decorative use of colour.

Good old Ghostscript saves the day, though:

gs -sDEVICE=pdfwrite -sColorConversionStrategy=Gray -dProcessColorModel=/DeviceGray -dPDFSETTINGS=/ebook -dNOPAUSE -dBATCH -dSAFER -q -sOutputFile=1983-A2L2013-m-a2-bpwp-grey.pdf -- 1983-A2L2013-m-a2-bpwp.pdf

By downsampling the scanned images and converting everything to greyscale, the result’s only 16 MB. All text and indexing from Acrobat is left intact.

gpiozero is rather good

gpiozero (‘A simple interface to GPIO devices with Raspberry Pi’) continues to impress me. One of its newer features is a pinout guide, accessed by the pinout command:

Raspberry Pi Zero pinout – click through for PDF

I’m trying to resist running it on every generation of Raspberry Pi that I have (B, A, 2B, 3B, Zero, Zero W) just for these pretty displays.

(ANSI console colours captured using script, then fed through ansi2html [from the Ubuntu colorized-logs package], printed to PDF from Firefox then mucked about a bit with in Inkscape)

inky phat draws a design

A bit dusty, and no sound, but worked out pretty well. (YouTube link if embed doesn’t work — inky phat draws a design)

Tiling based on plate 43, “a rotating motif …”, Wilson, Eva. Islamic designs for artists and craftspeople. New York: Dover Publications, 1988. ISBN: 978-0-486-25819-5

two-colour EPD displays are so pretty …

rotating tile pattern on Pimoroni Inky pHAT EPD display

This is a 600 dpi scan of a Pimoroni Inky pHAT EPD display. EPDs — electrophoretic displays, aka ‘e-ink’ or ‘e-paper’ — retain their image when turned off, so this Raspberry Pi had no power when I scanned it.

The image I made to fit the display is really small —

It’s a bit of a process making the images with just the right palette in GIMP, but I’m pleased how it turned out. I’d like to be able to write the vector images directly to the screen from SVG, but that might take some time.

InkyPhat-rotating2-212x104-web.svg
Tiling based on plate 43, “a rotating motif …”, Wilson, Eva. Islamic designs for artists and craftspeople. New York: Dover Publications, 1988. ISBN: 978-0-486-25819-5

maximal annoyance with the BBC micro:bit and MicroPython

I just picked up a micro:bit, the little educational microprocessor board originally from the BBC. It’s a nice little unit, though like all educational resources, it’s sometimes hard to access resources as a non-edu type.

I landed upon MicroPython, a Python language subset that runs directly on the micro:bit’s ARM chip. I rather like the Mu editor:
To give the old microcontroller grumps something real to complain about, MicroPython includes a bunch of very high-level functions, such as a powerful music and sound module. Getting the sound out is easy: just croc-clip a speaker onto the output pads:

(MicroPython warns against using a piezo buzzer as a speaker, but mine worked fine — loudly and supremely annoyingly — with a large piezo element. Some piezos have a fixed-frequency oscillator attached, but this simple one was great.)

This trivial example plays the Nyan Cat theme forever, but every time it loops it gets faster. The beats variable starts at the default 120 bpm, but is increased by one every time:

# nyan but it gets faster
import music
beats = 120
while True:
    music.set_tempo(bpm=beats)
    music.play(music.NYAN)
    beats = beats + 1

This starts out as merely irritating, but quite quickly becomes deeply annoying, and in mere hours become vastly vexing. I’m sure you’d only use this power for good …

Easy Raspberry Pi framebuffer screenshots with raspi2png

I gave a talk about retro-gaming on the Raspberry Pi yesterday. I was describing RetroPie, and I really needed lots of screenshots to illustrate games. I’m used to grabbing screens under X, but RetroPie runs without it, so all my usual tools were of no use.

I’d just found out about raspi2png, and it works really well! Usage is simple: just call it like

raspi2png -p outfile.png

and it’ll save whatever’s on the screen. It doesn’t play well with X, but there are already tools to take screenshots with that. As I was playing games, I didn’t want to have to pause the computer to take a shot, so I ran the command every five seconds for 30*5 seconds like this:

for f in {1..30}; do raspi2png -p retro_$(date -Iseconds).png; sleep 5; done

Here are some quality shots via raspi2png from Deathchase, officially the best ZX Spectrum game ever:

VM-CLAP1 👏 sensor + gpiozero on Raspberry Pi

Well, that was easy!

Since the Verbal Machines VM-CLAP1 sensor is an open collector type — that is, it sinks current when triggered — it behaves like a simple button to gpiozero, the Raspberry Pi Python GPIO library. If you attach a callback function to the sensor’s when_pressed event, your Python script will call that function every time it registers a clap.

The wiring is as simple as it could be:

 VM-CLAP1: Raspberry Pi:
 ========= =============
      GND → GND
      PWR → 3V3
      OUT → GPIO 4

This example code just prints clap! when the board picks up a 👏:

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

# Raspberry Pi gpiozero test for
# Verbal Machines VM-CLAP1 clap sensor
#   scruss - 2017-06
#
# Wiring:
#
#  VM-CLAP1:    Raspberry Pi:
#  =========    =============
#    GND     →   GND
#    PWR     →   3V3
#    OUT     →   GPIO 4

from gpiozero import Button
from signal import pause

def clapping():
        print("clap!")

clap = Button(4)
clap.when_pressed = clapping
pause()

This is a trivial example, but at least it shows that anything you can do with a button, you can also do with this hand-clap sensor.

Clap Sensor part for Fritzing

I have no idea if this wiring would work, but it’s pretty …

For work, I blogged about Verbal MachinesHand Clap Sensor VM-CLAP1 (“Clap on 👏👏, Clap off 👏👏 – Elmwood Electronics”). I’ve made a preliminary part for Fritzing for the board: VM-CLAP1 Clap Sensor for Fritzing.zip

It should work in Breadboard and Schematic mode, but absolutely doesn’t work in PCB mode. This shouldn’t be a problem, as it’s only available as a standalone board. Fritzing doesn’t have any way to create new parts from scratch any more, so I had to base it on a somewhat similar-looking board, the SparkFun Electret Microphone Breakout.

I’m looking forward to see what I can do with gpiozero and the clap sensor.

Headless Raspberry Pi + VNC: useful resolution

Breadboards of Canada …

I just set up a Raspberry Pi Zero to be a little breadboard computer. Running a headless machine only through SSH gets a bit dull at times, so the inclusion of VNC Connect in Raspbian is handy.

Only problem was that the default screen size — something like 720×480 — was too small for most dialogue windows. Here’s how to enable a more useful resolution of 1024 × 768.

All of these are enabled from the raspi-config tool, so open a terminal and start it with:

sudo raspi-config

Enable Boot to Desktop

Select 3 Boot OptionsB1 Desktop / CLIB4 Desktop Autologin:



Enable VNC on Startup

Select 5 Interfacing OptionsP3 VNC, and answer Yes to Would you like the VNC Server to be enabled?:


Set Screen Resolution

Select 7 Advanced OptionsA5 ResolutionDMT Mode 16 (1024×768) …:


Once you’ve enabled all of these, raspi-config will ask if you wish to reboot your Raspberry Pi. Once it has rebooted, you should have a usable remote desktop.

(All of the above screenshots were taken from a headless Raspberry Pi Zero via VNC.)

Before & After

These were taken later on a Raspberry Pi 2 I’m setting up for a maker festival booth:

decidedly smol: 720×480
fix it to 1024×768 …
so much better!

Simple — like, really simple — Arduino periodic timer with Brett’s MillisTimer library

I don’t know how many times I’ve written bad Arduino code to call a function every few milliseconds. Sometimes this bad code works well enough for my sketch to actually work. Often, it either doesn’t work at all or does something I really didn’t expect.

So on Arduino Day 2017, I’m glad I found out about bhagman/MillisTimer: A Wiring and Arduino library for working with millis(). It couldn’t be simpler to use: include the library, write the function you want to call every N milliseconds, set up the timer to run every N millis, and put timer.run() in a loop that’s called frequently. The library handles the timing and resetting all by itself.

As an example, here’s the eternal “Hello, World!” of the embedded world, Blink, rewritten to use MillisTimer:

// MillisTimerBlink - blink LED every second
//  using Brett Hagman's MillisTimer library
//  https://github.com/bhagman/MillisTimer
//  (or use Sketch → Include Library → Manage Libraries … to install)
// scruss - 2017-04-01

#include <MillisTimer.h>
MillisTimer timer1;               // new empty timer object
const int led_pin = LED_BUILTIN;  // use the built-in LED

void flash() {                    // function called by timer
  static boolean output = HIGH;
  digitalWrite(led_pin, output);  // set LED on or off
  output = !output;               // toggle variable state High/Low
}

void setup() {
  pinMode(led_pin, OUTPUT);       // use built-in LED for output
  timer1.setInterval(1000);       // set timer to trigger every 1000 millis
  timer1.expiredHandler(flash);   // call flash() function when timer runs out
  timer1.setRepeats(0);           // repeat forever if set to 0
  timer1.start();                 // start the timer when the sketch starts
}

void loop() {
  timer1.run();                   // trigger the timer only if it has run out
  // note that run() has to be called more frequently than the timer interval
  //  or timings will not be accurate
}

Note that MillisTimer only triggers when timer.run() is called. Sticking a delay(2000) in the main loop will cause it to fire far less frequently than the interval you set. So it’s not technically a true periodic timer, but is good enough for most of my purposes. If you want a true interrupt-driven timer, use the MsTimer2 library. It relies on the timer interrupts built into the Arduino hardware, and isn’t quite as easy to use as MillisTimer.

Keypunch029 — for all your punched card font needs …

A fairly accurate rendition of the 5×7 dot matrix font printed at the
top of punched cards by the IBM Type 29 Card Punch (1965).

Local copy: Keypunch029.zip.
Fontlibrary link: Keypunch029

The 029 (as it is sometimes known) generated a bitmap font from an engraved metal plate pressing on a matrix of pins. A picture of this plate from a field engineering manual was used to re-create the pin matrices, and thus an outline font.

029 Code Plate
029 Code Key

Historical Accuracy

The 029 could have many different code plates, but the one used here contained the characters:

<=>¬|_-,;:!?/.'"()@¢$*&#%+0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ

The character glyphs have been sized such that if printed at 12 points, the 029’s character pitch of 0.087″ is accurately reproduced. No attempt to research the pin matrix pitch or pin diameter has been made: the spacing was eyeballed from a couple of punched cards in my collection.

The earlier IBM Type 26 Card Punch (“026”) included a glyph for a square lozenge (Unicode U+2311, ⌑). The 029 code plate did not include this character, but I added it here for completeness.

The character set was extended to include:

  • all of ASCII, with lower case characters repeating the upper case glyphs;
  • sterling currency symbol; and
  • euro currency symbol.

While there may have been official IBM renditions of some of these additional glyphs (with the exception of euro) no attempt has been made to research the original shapes. This font set is intended to help with the visually accurate reproduction of 1960s-era punched cards, mostly coinciding with my interest in the FORTRAN programming language. No attempt has been made to use historical BCD/EBCDIC encodings in these fonts. We have Unicode now.

The 029 card punch could not produce any bold or italic font variants, but FontForge can, so I did.

Things I learned in making these fonts

  1. The 029 card punch printer could be damaged if you tried to print binary cards, as there was no way to disengage the code plate from the punch mechanism.
  2. FontForge really hates to have paths in a glyph just touching. Either keep them more than one unit apart, or overlap them and merge the overlapping paths.
  3. EBCDIC is weird.

Sources