Paolo Amoroso's Journal

Tech projects, hobby programming, and geeky thoughts of Paolo Amoroso

I bought a lovely little computer, a Raspberry Pi 400, and two accessories, a 64 GB Samsung Pro Endurance microSD card to hold the file system and a very cheap Full HD webcam for video calls.

Raspberry Pi 400, Samsung Pro Endurance 64 GB microSD card, and Full HD webcam product boxes.

I always wanted a Raspberry computer but assumed the components and cables would take up too much space at my work station.

Recently though I carefully inspected the layout of my desk, the HDMI ports of my HP Pavillon 23cw monitor, and the nearby electrical sockets. Researching the Raspberry Pi 400 convinced me I could set the device on the desk with minimal inconvenience and little space.

This is not a full review but a collection of early impressions and usage notes after working with the device for a week.


Although I have possible uses for the Pi 400, one of the reasons why I got it is not technical: the computer has a delightful form factor.

My daily driver, an ASUS Chromebox 3, is a high end desktop system. But the opportunity of using a different device with a nice form factor is a welcome and refreshing context switch that helps productivity and makes things fun. It's like writers spending time at Starbucks to get some work done instead of sitting and typing at their desk at home.

Another reason for getting the Pi 400 is I always loved Linux. Since switching to chromeOS in 2015 I've been thinking of how to set up a Linux box as a secondary computer within the constraints of my work station. The Pi 400 finally enabled this possibility.

Another major consideration that drew me to the Pi 400 is it's a full, native Linux system specifically designed as a combination of hardware and software to run Linux. Raspberry Pi OS is tightly integrated with the hardware and well supported, which will hopefully spare me the nightmares of Linux updates frequently breaking X-Windows back in the day.

Finally, I wanted a computer for experimenting with various computing technologies, such as ARM on the desktop. And, of course, I wanted an extra computer to play with Medley and other Lisp systems.

The Pi 400 is a member of the Raspberry family at the heart of countless electronics and IoT projects. But, since I'm not a hardware guy, I'll use it mostly as a desktop productivity and software development environment.


I extensively researched the Pi 400 and a key theme of what I learned is performance.

The reviews describe and evaluate performance through a wide range of experiences that doesn't make it easy to figure what to expect. Perhaps because the specs place the device at a spot of the performance spectrum along the transition between realizing responsiveness is suboptimal, and not noticing anything unusual about the way the system reacts.

Therefore, given the affordable price, I accepted the small risk of disappointment and went with the Pi 400.

What I think the reviews don't highlight enough is that, even at the lower end of the performance spectrum, Raspberry absolutely nailed the combination of form factor and price of the Pi 400. It sits at a local maximum in the product space that delivers tremendous value for the money.


The Italian keyboard of my Pi 400, which makes up the entire device, has nearly the same size as the TedGen keyboard of my Chromebox. The keys of the Pi 400 are actually slightly larger than those of the TedGen and support well my typing speed, which is not much.

I feel at ease with the Pi 400 keyboard because I prefer short-travel chicklet units. The plastic feel and feedback aren't an issue for me as, again, the mechanics and build don't interfere with my relatively slow typing.

Although not as smooth and precise as the Logitech mouse of my Chromebox, the Pi 400 one is acceptable despite the occasional lower than average responsiveness.

The Pi 400 instantly recognized the new Full HD webcam as well as my Mixcoder E9 Bluetooth headphones and Brother HL-L2340DW wireless printer. The webcam delivers a smooth feed with Google Meet and good image quality for the price.


I've been using Unix since the early 1990s and Linux since the mid 1990s, so the Raspberry Pi OS desktop and system look mostly familiar.

I personalized the desktop environment to make it look similar to my Chromebox. I set a similar background color, moved the taskbar to the botton like the chromeOS shelf, and set Chromium as the default browser with a matching tab layout.

This is what my Raspberry Pi OS desktop looks like:

Raspberry Pi OS desktop on a Raspberry Pi 400.

Since my daily driver on the desktop is a Chromebox I mostly live in the browser, with a number of tabs often open on Google products. On the Pi 400 Chromium works well enough with Google web apps. But I can't synchronize my extensions and settings with chromeOS as Google removed the functionality from Chromium.

Although most of the programs I need are available, I haven't found an easy to install screencasting tool with Wayland support.


I don't leave the Pi 400 permanently on the desk but set it up on demand.

Whenever I need the device I bring it out, set it on the desk, and connect the cables. One of the cables goes into the HP monitor which the Pi 400 shares with the Chromebox. I can use either computer by switching the monitor input signal with a button.

The only Ethernet wall socket close to the desk is permanently hooked to the Chromebox. The Pi 400 accesses the network over Wi-Fi at up to 70-80 Mbps.

Setup and configuration

To initially set up the Pi 400 I connected it to the Ethernet socket so the required large file downloads and system updates could go faster.

For installing the operating system on the microSD card I originally planned to run the Raspberry Pi Imager tool on my Chromebox under the Debian based Crostini Linux. But, although Raspberry Pi OS is derived from Debian, the only binaries of such an essential tool are available only for Ubuntu. Raspberry does provide instructions for building a package for Debian but network installation on the Pi 400 seemed simpler.

I selected the 64-bit version of Raspberry Pi OS Bookworm desktop and recommended software.

Despite the simplicity of the process, which can complete in less than a quarter of an hour, it took me three reinstallations and a couple of hours because of a subtle Raspberry Pi Imager bug.

I also configured SSH and headless access to the Pi 400 from my Chromebox with the recommended VNC client TigerVNC, the only one that supports Wayland on Raspberry Pi OS Bookworm. But the Pi 400 is just too slow and laggy over VNC with my setup, which makes it viable in a pinch.


The Pi 400 is no gaming rig but delivers enough performance for most ordinary tasks without the feel of constant wait and lag.

This supports well the kinds of tasks I ordinarily carry out such as running a browser with half a dozen tabs, a terminal, and another program or two. I don't consume much media.

The most noticeable manifestation of performance limitations is that programs don't start up instantaneously. For example, Chromium comes up in about 4 seconds. But once programs start, they run with mostly instantaneous responsiveness for common tasks.

YouTube streams consistently smoothly over Wi-Fi at 1080p and full screen, but entering or leaving full screen mode freezes the browser for a few seconds.

I don't mind the overall experience as I'm used to systems with similar architecture like cheap Android tablets and Chromebooks. The Pi 400 actually feels snappier than my Lenovo Yoga N26 Chromebook.

Although not architecturally similar to the Pi 400, the 8-bit single board computers I use for my retrocomputing projects, such as the Z80-MBC2, deliver a comparable feel that's part of the expected experience.

Speaking of retrocomputing, one the reason I got the Pi 400 is to run Medley, other historical Lisp systems, and emulated classic computers at a level of performance closer to the originals. Running Medley on powerful desktop systems or in the cloud is much faster, thus limiting the appreciation of certain design decisions, features, or workflows the systems imposed back in the day.

The more I use the Pi 400, the more the perception of not operating a powerful computer is fading away as I focus on the tasks I use it for.

An example can express and synthesize this perception. As I said earlier, I configured the desktop environment of the Pi 400 to look similar to that of my Chromebox. The Pi 400 often feels so smooth I forget I'm not on the Chromebox.


it's been a week since I unboxed the Pi 400 and I love it.

The product has the perfect combination of features, form factor, and price for my needs. This surprisingly capable little computer is one of the rare lovely products that encourage to use it, be productive, and have fun.

#pi400 #linux

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Although Medley's documentation and published material is scattered across several archives and sources, and doesn't cover all the system facilities, once I find the right document I get most of the information I need on a specific feature.

But sometimes the information is not up to date because Medley is still under development after so many decades.

I bumped into such a case when experimenting with TableBrowser, Medley's tabular data browser tool on which the system file browser is built. Other applications can access and control from Lisp TableBrowser, which is a reusable component with an API.

Before program development with the API, TableBrowser requires setting up a specific environment by loading a source file with some declarations, which are not needed when running compiled applications. The Lisp Library Packages manual explains how to set up the environment in section “Installation” of the “TABLEBROWSER” chapter on page 283 of the PDF. Here the manual provides the File Manager commands to add to the source file of an application that uses TableBrowser:


But in spite of following these instructions I got an error when calling TableBrowser functions.

It turns out that, as a result of the recent modernization work the Medley Interlisp Project is doing, some source files were rearranged and moved. So now all it takes to set up the Lisp environment for development with TableBrowser is the form (LOADCOMP 'TABLEBROWSER), for example in the coms of the program under development.

#Interlisp #Lisp

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The short ebooks on Intel 8086 Assembly programming Oscar Toledo self published are some of the best 8086 resources I've seen.

After introducing the 8086 instruction set and Assembly, Programming Boot Sector Games describes the source code of several games each of which fits into the boot sector of a PC, 512 bytes. The sequel, More Boot Sector Games, covers more games.

The introduction to 8086 insructions in the first book is short and to the point. It's enough to code fairly advanced programs without overwhelming with information as processor manuals and full length books typically do. But Oscar also shares his considerable experience and insight by discussing many 8086 tricks, idioms, practical advice, and optimization techniques.

The books cover not only games but also other interesting 8086 programs such as a BASIC interpreter and a tiny operating system.

Since some of the code is dense and advanced, reading it once may not be enough for a full understanding. But a great feature of these programs is they fit into 512 bytes, so there's an upper bound to complexity which rereading the code and the text helps overcome.

The only downside of the books is they are password-protected PDF files. It's an annoyance when opening them in ereading apps but is easy to overcome.

#assembly #books

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Since encountering Medley I gained considerable experience with Interlisp. Medley Interlisp is a project for preserving, reviving, and modernizing the Interlisp-D software development environment of the Lisp Machines Xerox created at PARC.

Nine months later I know enough to find my way around and confidently use most of the major system tools and features.

I read all the available documentation, books, and publications, so I know where to look for information. And I undertook Interlisp programming projects such as Stringscope, Braincons, Sysrama, and Femtounit.

Now I'm ready to explore Medley as a Common Lisp development environment.

Although most of the system, facilities, and tools are written in and designed around Interlisp, the companies that maintained and marketed Medley over time partially implemented Common Lisp and integrated it with the environment. The completion level of the implementation is somewhere between CLtL1 and CLtL2, plus CLOS via Portable Common Loops (PCL).


I want to widen this experience to Common Lisp.

I'll leverage the more advanced Lisp dialect and interface with Interlisp's facilities as an application platform that comprises a rich set of libraries and tools such a window system, graphics primitives, menu facilities, and GUI controls for building applications. Each world can interoperate with the other, so Common Lisp functions can call Interlisp ones and the other way around.

Developing Common Lisp programs with Medley is both my goal and a way of achieving it through practice. Medley is an ideal self-contained computing universe for my personal projects and Common Lisp greatly enchances its toolbox.


The main tools for developing Common Lisp code are the same as for Interlisp: the SEdit structure editor for writing code; the File Manager, a make-like tool for tracking changes to Lisp objects in the running image and saving them to files; and the Executive (or Exec), the Lisp listener.

However, the workflow is subtly different.

In some cases taking advantage of the integration with Medley involves different steps for Common Lisp code. For example, defining and changing packages so that the File Manager notices and tracks them needs to be done in a certain order. And there are Medley extensions to the package forms.

When working with Common Lisp I open at least two Execs, a Common Lisp and an Interlisp one. The former is for testing, running, and evaluating Common Lisp code.

The Interlisp Exec is for launching system tools and interacting with the File Manager. Since all the symbols of SEdit, the File Manager, and other system tools are in the IL Interlisp package, in an Interlisp Exec it's not necessary to add package qualifiers to symbols all the time.

Exec commands such as DIR and CD work the same in both Execs.


Medley's Common Lisp features aren't documented in the Interlisp Reference Manual, the main information source about the system. The reason is the companies that distributed and maintained the product ceased operations before the work on implementing and documenting Common Lisp was completed.

I found only a couple of good sources on Common Lisp under Medley.

The implementation notes and the release notes of Lyric, the music-themed codename of one of Interlisp-D's versions, provide an overview of the integration between Common Lisp and Medley. The release notes of Medley 1.0, a later version, expand on this. Issue 5 of HOTLINE!, a newsletter Xerox published for its Lisp customers, has useful step by step examples of creating and managing Common Lisp packages the Medley way.

Some of the system code of Medley is written in Common Lisp and may be a source of usage examples and idioms. I'm also writing Common Lisp code snippets to test my understanding of the integration with Medley.

#CommonLisp #Interlisp #Lisp

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Planet Python carried out my request to remove my blog from the aggregator. Now their feed no longer syndicates my posts about Python, which I'll no longer write much about.

Planet Python is an aggregator of blogs, podcasts, and other resources of interest to the Python community. In late 2019 I submitted the feed of Python posts of my old blog, later updating it to point to my new blog.

I was learning the language and sharing on the blog my experience with coding projects and other experiences. But although I had great fun with Python and accomplished a lot I'm proud of, my interest waned as I rediscovered my old love Lisp.

I encountered Scheme in the early 1990s at an introductory computer science class based on Structure and Interpretation of Computer Programs, fell in love with the Lisp family of languages, and learned Common Lisp and Emacs Lisp. Lisp became my only language until the early 2010s when real life claimed my time and attention. Near the end of the decade, intrigued by Python and its massive ecosystem, I decided to learn it.

At the beginning of 2023 I discovered Medley Interlisp and got hooked.

Using Interlisp and its environment made me realize Lisp is the language that comes most natural to me, I'm most productive with, and gives me joy and not just fun. I never mastered and enjoyed other languages to the level of Lisp. And my projects turned out not to need Python's batteries.

I'll still maintain a reading knowledge of Python and keep up with its ecosystem. But this journey made me readjust my focus on Lisp, now my only language.

It's good to be back home.

#Interlisp #Python #Lisp #blogging

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I integrated Femtounit with the File Manager by defining the new type TESTS for Femtounit tests and redefining DEFTEST in terms of it.

It turns out it's not a good idea as the tests get duplicated. The DEFTEST macro expands into a DEFINEQ function definition and the File Manager notices both, the DEFTEST form of type TESTS and the function of type FNS.

The fix seemed simple, assigning tests to an existing type such as FNS. First I removed TESTS with (DELDEF 'TESTS 'DEFINE-TYPES), then replaced the type argument TESTS with FNS in the XCL:DEFDEFINER form. But when I tried to edit a sample test TEST.PLUS for the PLUS function with (ED 'TEST.PLUS :DONTWAIT), SEdit quit with the error:

Warning: Couldn't find a hash-table for FNS definitions.
One will be created.
Could not find fns definition for TEST.PLUS.
Could not find fns definition for

Back to the drawing board.

#femtounit #Interlisp #Lisp

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My old blog post Why your blog still needs RSS was shared on Hacker News, made it to the home page with about 250 upvotes, and so far generated almost 9K views. I'm pleased as it hints there's still a lot of interest in RSS.


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I integrated Femtounit, my Interlisp unit test framework, with the File Manager and the SEdit structure editor.

To achieve this I defined the new File Manager type TESTS for Femtounit tests and redefined DEFTEST in terms of it, then tweaked the code formatting of tests in SEdit. Now the system notices and keeps track of new and modified tests.

Here's the File Manager type menu, which SEdit pops up when opening a test, with the DEFTEST option highlighted under TESTS:

Interlisp File Manager menu with the Femtounit types.

Also, now SEdit handles and properly formats test definitions like this of a function SQUARE to compute the square of its argument:

SEdit editing a Femtounit unit test definition on Interlisp.

Implementing the new features was much easier than expected.

The traditional way of adding types to the File Manager, described in the Interlisp Reference Manual, involves writing a dozen functions for most of which it's not clear how they're supposed to work. Medley 1.0 added support for two easy to use File Manager type defining forms that replace all that, XCL:DEF-DEFINE-TYPE and XCL:DEFDEFINER. This code is all it took for Femtounit's new TESTS type:

(XCL:DEF-DEFINE-TYPE TESTS "Femtounit unit tests")

                            (LAMBDA (NAME)
                              (AND (LITATOM NAME)
                                   `(DEFTEST ,NAME ("Arg List")
                (NAME PARAMETERS &BODY BODY)

This additional tweak makes SEdit format and indent DEFTEST unit test definitions the same way as DEFUN function definitions in Common Lisp:


The simplified process is not discussed in the Interlisp Reference Manual, where I'd have expected, but in a more obscure source, the Medley 1.0 release notes from page 52 of the PDF document. My proactive reading of all the documentation paid off as it let me spot such crucial information and save a lot of work.

#femtounit #Interlisp #Lisp

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Today I attended the funeral service of my beloved mother who passed away peacefully two days ago.

I'm signing off a nearly continuous shift as a full time caregiver started almost 13 years ago. Over this long time I took care first of my father, then a sister of my mother, and finally my mother. The years of the pandemic were the most demanding and exhausting, constantly pushing me to the edge of burnout and forcing me to take some time off.

I assisted my dear family members until their very end to the best of my capabilities. Now I'm ready and eager to start a new life.


Discuss... Email | Reply, the blogging platform I use, lets me embed a YouTube video in a post by just inserting the URL in a blank line of the Makrdown source.

It's a valuable feature with a major drawback: YouTube embeds contain user tracking code by Google. I don't mind such trackers but my many privacy minded readers do.

As a workaround I could insert the trackerless code YouTube provides, but the design of the video player is not responsive and gets cropped on mobile screens. relies on for YouTube and other embeds and doesn't support trackerless embeds. I and others tried to bring the issue to the attention of the developer but not much happened.

Managing tracking and cookie consent is a hassle, so what to do? I just went ahead and replaced the half a dozen embeds of my blog with links to the corresponding videos on YouTube.

A nice side effect is the Blacklight privacy inspector now reports 0 trackers and cookies on my blog.

#blogging #Google

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