But it's only a single piece... 
...outside... 
...on a park bench... 
...where people sit with their backs to it! :)


 <img alt class="doksoft_image_img" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/20230422_141727b.jpg?v=1690915936" width="500" height="369">


Last year, Cambridge City Council announced a new initiative called "Art Benches" where artists, unable to get exhibition space in a traditional gallery, could submit their work for display in one of the custom-built benches in Christ's Lane, in the town centre. Mine was one of those selected!

 

If you're in the area, it can be seen until mid-end of May.

If you're not, then I've included a selfie of it in situ.


 <img alt class="doksoft_image_img" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/20230422_141700.jpg?v=1690915937" width="375" height="500">

Sir Clive Sinclair as public art

At the start of February I presented a talk at the open source conference, FOSDEM. For those that know me, this will be no surprise as I've been involved in open source for nearly 30 years, and attended every FOSDEM since they started.

This year I opened the "Emulator Development" devroom with a talk entitled, "7 things I learned about old computers". That video is now available online.


 <a href="https://fosdem.org/2023/schedule/event/seven_sins/">https://fosdem.org/2023/schedule/event/seven_sins/</a>


Although I don't know why the URL slug mentions "seven sins", I do know that some of the stories in the talk feature in the book so if you want to be surprised - don't click the link!

This picture from the session, however, contains no such spoilers...


 <img alt class="doksoft_image_img" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/IMG-20230205-WA0005.jpg?v=1690915940" width="500" height="281">

Spoiler alert!

Then might I suggest reading through the source code to some of the classic games of the early 80s like Zork, Star Wars, Centipede, Dig Dug, and Hitchhiker's Guide to the Galaxy.

https://github.com/historicalsource

Some are written in ZIL (Zork Implementation Language) but most are assembly, so a little experience is necessary to make the most of them. The brave ones amongst you might even manage to build the code into working binaries - good luck!

For those wanting something written in a more current language, and consider C++ to be such a thing, then newer titles like Jedi Academy for the XBox are also there.

Bored over the holidays?

This was one of the last things I filmed before the 2020 lockdown. aka "The Before Times" I thought it deserved a second airing for those that only came to know me as a consequence of this book!

It's a quick stroll down 983D University Avenue, in Los Gatos, to visit what was once the office of the most famous computer in the world. (imo!)


 <a href="https://www.youtube.com/watch?v=gMWfdj9qMOM">https://www.youtube.com/watch?v=gMWfdj9qMOM</a>


(and yes, the manuscript is still with the editors!)

Here's a short video interlude!

...here's a short musical interlude!

It's a remix I created of the BBC Micro classic "Cold Tea."


 <a href="https://www.youtube.com/watch?v=iAXYZhbhMuc">https://www.youtube.com/watch?v=iAXYZhbhMuc</a>


Originally, it was an improvised piano piece performed on Hungarian TV by Andrew Robinson, but I first heard it in the computer room at school. It was on a disc of several tunes which got copied around everyone in the year. Imagine a room with 20 BBC micros, each playing a different tune!

This version was created by using BeebEm to capture the video (and audio) of the first part, which I then mixed into the remix section. Since I'm rather poor at playing by ear I hacked the original program (written in BASIC) to output the notes to the screen, which I duly redirected to the virtual printer. (i.e. a text file.) A quick piece of Javascript to convert this list of notes into a MIDI file, and I was ready to start work arranging the notes.

If you've never heard the original piano version it is, like everything else, available on YouTube.


 <a href="https://www.youtube.com/watch?v=53HEFvFPLLY">https://www.youtube.com/watch?v=53HEFvFPLLY</a>


The pinned comment is even from the composer himself!

While the manuscript is with the editors...

All supporters favourite machines have been completed, the type-in game is ready, permissions for the images have been collected, and the main prose is done...

...now is the time for editing.

And it nicely coincides with our 700th supporter


 <img alt="" class="doksoft_image_img" src="/images/18429/preview/medium" width="328" height="500">

The writing is complete!

I have now received a PDF with 48 favourite machines for inclusion in the book. The results are, shall we say, "interesting"!?!? :)

With a comparatively small sample set there was always the opportunity for lesser-known machines to be well represented. I hoped there'd be a Dragon 32 and a Jupiter Ace - and I got them. I wanted a Sinclair QL - and I got one. But there was only one mention of a ZX Spectrum in the whole list, yet two for the Netronics Elf - wow!

(The four votes to see the Commodore 64 in there, however, was not a surprise.)

When the UK heatwave stops melting my keyboard (and my brain) I shall be ordering all the machines into sequences that form twisty little passages between various other sections in the book!

Another milestone reached!

Although the book isn't heavy on statistics, I do feature a few bar charts, and drop a few pieces of original research, such as the most common reason for a number appearing in a computers name. (Do you think it'll represent the memory available? The Nth computer made by that company? Or the year in which it was released?)

To facilitate this, I created a series of machine-readable JSON files that could be processed, and re-processed as new data became available. If you'd care to engage your geek credentials those data files are at:

https://github.com/MarquisdeGeek/20-GOTO-10

But before you go, remember: 
* this is not a complete set of every computer ever made, just a top-of-mind selection 
* these files contain "best available data", choosing first hand sources over Wikipedia, when available 
* they have not been formally checked, if such a thing is even possible.

(Release early and release often, as they say.)

Pull requests are welcome to accept changes, additions, and fixes.

Also note that this is NOT the "your favourite machine" pledge, it's simply a collection of data. It will provide background and support for some of the book contents, and maybe even become a useful resource in its own right. Who knows?

Github - For the geeks!

This is a sign that we've reached the beginning of the end! Each pledge that contains something which affects the contents of the book has been removed, so the information can be gathered and incorporated. Whether it's a picture of your computer, the contents of 10 PRINT "...", or simply your favourite machine, we are gearing up to receive them!

(Pledges for the book, posters, and cross-switch will remain open a little while longer.)

So start thinking earnestly about your contribution(s), as the publisher will be in contact "Any Day Now"(TM)

The first round of pledges have closed

This weekend is the 40th anniversary of the Sinclair ZX Spectrum. With that in mind I've added a poster of the character set to the available rewards. (I also added one for the Commodore 64, just to stop any playground bickering that might re-emerge!)

I shall also be attending various meetups and celebrations for the 40th over the next month. If you see me at one, do say hello and share your memories and stories.

As far as the writing goes, I've completed almost everything I intended to, so we'll soon start closing up the campaign so we can collect all of those favourite machines and photographs from you good folk, and incorporating them into the prose. (There's still an opportunity to someone to supply a type-in game, if anyone's keen to upgrade.)

Let's hope the weekend celebrations bring in some more supporters for our little group - 672 supporters and still climbing!

More birthday silicon!

On the 7th April 1986, Amstrad bought Sinclair.

But this post is to not debate the merits of the deal. Rather, to highlight the frailty of first hand sources.

In the book "What You See Is What You Get", Alan Sugar (or, more probably, his ghost writer), comments about this deal and how he needed to have someone take a cab from London to the river Ouse near Ely, with a bankers draft, to get the Sinclair IP rights signed over to Amstrad, as part of the takeover deal. On a bank holiday.

You can tell from the writing (see: Exhibit A) that he's clearly frustrated with the process, by calling the person who wrote the ZX Spectrum ROM a "bloody hippy" and that this hippy wouldn't travel from Cambridge to London on a bank holiday to sign over the rights.

(This is a few paragraphs after Sir Sugar points out that he flew to Florida to be with his family for a holiday, and how important that is.)

Except it didn't quite happen that way.

Only one of the facts above is correct - the date!

Last night I was doing research on this topic and double checked the facts... by going to the pub with this "bloody hippy" and asking him!

 

Exhibit A: https://www.amshold.com/social_media/the_sinclair_story.htm

Last night I was doing research...

Spoiler alert: It isn't!

Nor is it enough for our group of supporters as it's currently at 643, or 113%, and still rising!

Over the last month I've focused on the writing, rather than outreach. Amongst other topics, there's now a piece on how hardware was used to fix a software bug, the problem of True being 1 or -1, and the infamous quote above.

Currently, I have 84 entries written, 16 partially written and 816 random ideas and thoughts that need a home! The latter being both notes for fully-fledged sections, and pieces of arcane knowledge that will be dropped into existing pieces to bring a little extra colour. After all, retro is meant to be fun, so expect name drops for various shows, actors, and books to give context of the time period and reflect the positive aspects of the 1980s.

640K is enough for anyone

Last night, around 9.30pm UTC, we hit the 100% mark... and a short while later, 101% - thanks for everyone that tweeted, retweeted, posted on blogs, forums, and other socials. As you can see from the totals, it really made the difference.


 <img alt class="doksoft_image_img" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/20220126_213947-fix.jpg?v=1690915955" width="375" height="500">


I'm meeting with the publishers tomorrow to work out the next steps, and tonight I'll be writing about why Commodore 64 had 64kB of RAM, yet the boot screen showed only 38,911 bytes.

There will be more updates as the writing and publishing process continues, letting you all in on the secrets, but until then I'll end with a line from that classic Gerry Anderson show: "Thunderbirds are GO!"

We did it! Thank you so much!

In 1982 the two titans of the school playground were released - the Commodore 64 and the Sinclair ZX Spectrum- along with, at least, 13 other machines. Although it was certainly the year in which the biggest sellers were released, it was not the peak for quantity. In 1983, at least 19 machines were put in front of the public for the first time. Or rather, of the 106 machines I've so far cataloged, those are the current stats!


 <img alt class="doksoft_image_img" height="225" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/year-of-release.png?v=1690915927" width="500">


Last week the folk at CocoTalk invited me onto their show, where I gave an interview about my journey with retro and gave some sneak peaks of the book. It's around 90 minutes long, and at the beginning of the show, which you can (re-)watch here: <a href="https://www.youtube.com/watch?v=DVi99Xx6T-o">https://www.youtube.com/watch?v=DVi99Xx6T-o</a> 
 
Next month, on the 5th February, I will open the retrocomputing dev room at FOSDEM, the largest open source conference in Europe, with a talk about ZX 1K Chess. There will also be a short Q&amp;A session afterwards. <a href="https://fosdem.org/2022/schedule/track/retrocomputing/">https://fosdem.org/2022/schedule/track/retrocomputing/</a> 
 
Those are the first two of my promotional activities to find the final 15% of our group. Please forward them (or this page) to your social channels and forums to entice anyone that might have missed the previous announcements. And because we're almost there, we have a discount code for them: ALMOSTJAN22 
 
As always, this book won't exist without your help, so if you know someone that runs a blog, podcast, YouTube channel, magazine, conference, or outlet where we can find some more supporters, then please tell them about this book - even if it's not about computing, games, or retro! (People have other interests, too, it seems!) Some of the most gratifying wins have happened when a seemingly unrelated blog posted a link.

At 85%, we are nearly there!

As we close the year which gave us the 40th anniversary of the Sinclair ZX81, Acorn BBC Micro, TI-99/4A (and several others), we look forward to 2022 for the 40th anniversary of even more machines - the Sinclair ZX Spectrum, Dragon 32, Oric, Jupiter Ace, and Vectrex, to name just a few off the top of my head!

What a iconic celebration it would be to also complete the crowdfunding campaign, and get the book into yours hands, in 2022!?

In the new year, I'm going to be pushing hard on all fronts to find the final 31% of the folk we need to join our retrocomputing band, and get this over line. But this book won't exist without your help, so if you know someone that runs a blog, podcast, YouTube channel, magazine, conference, or similar outlet where we can find some more supporters, let please tell them about this book. (I also give a fairly decent interview, even if I do so say myself!)

Expect more updates in the new year, including a reference to what's in Appendix 50!

Happy holidays to you all!

This update is one that lets you peek behind the scenes at how the book is being written. For sure, I have several pages of anecdotes about Spanish import tax, the placement of cursors on the keyboard, and the joys of C90 cassette tapes, but I also have to deliver on providing a "choose your own adventure" style game book. How will that work?

Over the last couple of weeks I've been writing code which takes a directory full of markdown text files containing the book content, along with its associated metadata, and builds it into a single (large) markdown file. These metedate files indicate the direct links between each separate section, as well as descriptions of groups of articles which are all linked to one another. (If you remember webrings, you're on the right track.)

<img alt class="doksoft_image_img" height="380" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/goto10-folders.png?v=1690915931" width="233"> 
An example of some of the numbers featured, and the shortened section name.

There are currently 136 such folders, with many more to add. Perhaps the obvious content, that of the machines themselves, will be the final ones to be included. That is because I am waiting to see which are the most popular ones, according to the supporters of the book. I hope to have around 400 entries, to match the Fighting Fantasy books, but I'll let quality content take priority over whimsical desire.

 
With this code in place I was also able to incorporate a digraph library, to render the connections between each section. It currently looks like this:


 <img alt class="doksoft_image_img" height="425" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/goto10-book-reworked.jpg?v=1690915931" width="500">



 Click the image to see the gory details


You will notice that it looks a mess (such is machine-generated content, at times!) but otherwise, it shows how many connections there are, and gives you an idea of the type of journey you will make when reading the book. Although this graph will grow and change as we edge closer to completion, I've still decided to hide the section names, to maintain the surprise.

There are also some sections which are disconnected. In most cases this is because I haven't yet written the prose which connects them. In (at least) one specific case it is intentional, as you won't be able to discover these section(s) unless you cheat and read the prose written between the other sections! (An easter egg, if you will)

There is also a 'Game over' section, with no ongoing links. This is for when your decisions have taken you to the entry which designates the death of retro computing. As to which number represents that, I'll leave you to ponder!

This is your call to action! For us to complete the book, and get it into your hands, we need more supporters. So if you're part of online social media, email group, or work forum then please post a link to the book. Even if you think there's no one there interested in retro computers you may be surprised at how many of us there are! Or how many people who would pledge for the book, as a present to others. Thank you!

 

https://unbound.com/books/20goto10/

Behind the scenes

There are so many things connected with the number 64. The 64K address space of 16 bits (0 to 65535). The numeral on machines such as the Dragon, Pecom, and Oric Nova. And the year in which BASIC was created.

But it's also the threshold in a slightly obscure piece of Spanish legislation from September 1985. The law was that any imported computer with 64K (or less) memory, would be taxed at the rate of 15,000 pesetas per machine. Consequently Amstrad, who were wanting to sell their 64K CPC 464 machine into the Spanish market, would see their 25,000 peseta price tag raised to 40,000. That would certainly kill any chance of sales in the country. So they upgraded the RAM to 72K, by adding an 8K chip onto a new daughterboard.


 <img alt class="doksoft_image_img" height="281" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/20211009_155641-small-topview.jpg?v=1690915959" width="500">


However, as we've seen, the address space of a 16-bit machine is only 64K so extra circuitry would be required to make use of this memory. Other computers of the era would using bank switching technology, or something similar, allowing the programmer to choose which memory chip (in its entirety) would be used at any given time. Amstrad didn't. Their solution was simply to not connect the chip! This meant they could print 72k on the case, show any customs officers who might interested that there were 72k worth of memory chips inside the machine, and import their machine into the Spanish market at a reasonable price.

It was called the Amstrad CPC 472.

It is not known if these chips even worked. Maybe they were taken from the rejects bin at the chip supplier, Orion. It is not even known if the Amstrad engineers in the UK added the board, or if the work was carried out by the Spanish distributor, Indescomp. Rumours and theories abound, but the pictures prove the existance of this fabled machine.


 <img alt class="doksoft_image_img" height="281" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/20211009_155748-smalle.jpg?v=1690915959" width="500">


What you can't see from the picture is how stiff the cabling is. It is almost impossible to turn the board over any more than it is in this picture. That, at least, would make it difficult-to-impossible for a casual tax inspector to notice that the pins were not connected.

 
I think this story exemplifies the nature of the book - lots of stories, connected by numbers in ways you might not have considered. After all, for many people, the story of Amstrad begins with tape-to-tape cassette recorders, and ends with their purchase of Sinclair. Yet, in the Amstrad community this tale is as well-known as Roland!

 
So please send this update around your friend social media sites and online forums, so we help more retro computing fans discover something outside their usual circles!

We're at 64% ! So here's a post about 64 but (surprisingly) is not about Commodore!

There's a brand new reward available, especially for fans of the late Sir Clive Sinclair - a framed cross-stitch of a ZX Spectrum key, custom-designed and hand-made by Lil' Fluffy Crafts. 
 
<img alt class="doksoft_image_img" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/20210924_114110.jpg?v=1690915944" width="500" height="469">

If your name doesn't begin with 'G', as shown in the picture, then ask for your preferred letter and a suitable key will be made, matching the original keyboard style and colours.

 
<img alt class="doksoft_image_img" height="500" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/IMG_4975.jpg?v=1690915944" width="500">

You can upgrade your existing pledge by following the guidelines here: 
<a href="http://help.unbound.com/en/articles/3159595-how-do-i-upgrade-my-level-of-support">http://help.unbound.com/en/articles/3159595-how-do-i-upgrade-my-level-of-support</a> 
 
This update is only being sent to our existing supporters as a thank you for being awesome! So upgrade your own pledge, or let your closest friends know about it now, since next week we announce this to the public at large, and we don't want you to miss out!

Ssssshhhh!

From 0 supporters to 255 of them in less than two months - what an amazing thing you've all done to help raise the profile of retrocomputing even further!

As most of you will know 8-bit machines can stored 256 distinct values, usually numbered 0 to 255. (Although this range can also be interpreted as -128 to 127, but we'll cover that in the book.) For this update, I'll merely point out that an 8-bit value can not store the number 256.

"So what?" you might ask.

Well, since 8-bit machines would often store data in CPU registers with only 8 bits they couldn't represent the numbers 256 or higher. So the number 256 would simply "wrap-around" to 0. And 257 would appear as 1. And 258 would be 2. And so on.

So if this value represented the level in a computer game, for example, and the player was never expected to reach level 256, then there would be no problem. But even if they did reach that level, the programmer might believe the game would function as it normally did on level 0. But if that game was Pac-Man, and the first level was 1, not 0, then something beautiful happened... 
 


 <img alt class="doksoft_image_img" height="288" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/pacman-kill-download.jpg?v=1690915919" width="224">


...this is the infamous “Pac-Man kill screen” and I'll talk more about it in the book, as an excuse to uncover other technical quirks and bugs. (Some with numbers as low as 13)

But for now let's just say that it isn't the level data which corrupts the screen, it's the level counter! Pac-Man described each level by a row of (up to seven) fruits, drawn in the bottom right corner of the screen. If that level was 256, the level counter would draw fruits from 1 to 256, which it would view as being from 1 to 0. Since the program code that drew these fruits didn't consider this possibility it didn't stop at seven fruits, and kept going until all 256 were drawn. Because of this, and quirks in the way the fruit graphics were stored, and the way the screen memory is positioned, meant that non-fruit graphics were used and drawn vertically down the screen, from right to left.

What a mess!

So please share this update with your friends, social media contacts, and on any forums to which you belong to remind everyone of the content they're missing, and to help get us closer to our target so we can all have the book with this (and many other) stories from the retro computing era.

 

p.s. even the best programmers I know have, at least once in their lives, tried to fit the number 256 into 8 bits. Yours truly, among them!

256: 0 To 255

This number is halfway between the number of supporters I had when I started to write this, and the number I had when finishing it! It is rather an amusing number, as it forms the foundation of the (in)famous Commodore 64 BASIC program:

10 PRINT CHR$(205.5+RND(1)); 
20 GOTO 10

This prints a random stream of <img alt class="doksoft_image_img" height="16" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/c64-205.png?v=1690915915" width="16"> and <img alt class="doksoft_image_img" height="16" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/c64-206.png?v=1690915915" width="16"> graphical characters which ultimately form a maze, scrolling up the screen.

It does this by relying on a number of implicit facts about the implementation of Commodore BASIC. Firstly, it uses the fact that all floating point numbers (i.e. those with a fractional part) will be rounded down to the nearest integer. Down. Never up. It is a process known as 'truncation' and is in contrast with the various rounding techniques used elsewhere, such as 'half round up' (or common rounding), 'symmetric' rounding, or 'banker's rounding.' However, it doesn't perform this truncation just yet. The BASIC interpreter only performs truncation when it needs to. And it needs to do that in the third step.

The second part, RND(1), indicates that we want a random number between 0 and 1. Again, this is a fraction, making the result somewhere between 205.5 and 206.5. And because we use 0.5, the ratio of each symbol is 50:50. If we used 205.1, for example, this would be closer to 90:10. The RND(1) instruction on other versions of BASIC might instead use RND(0) to achieve this result. (But we'll cover that in the book!)

The third step passes the sum, of 205.5 and the random number between 0 and 1, to CHR$ which converts a numeric integer into a character. Every computer has a set of these characters where one number maps directly to one symbol. Most of the time these symbols are recognisable letters of the alphabet, or single digits. Sometimes they're graphical images. Since all character sets are referenced by integers, the BASIC interpreter running this program spots the floating point number and truncates it, to either 205 or 206, so that CHR$ can generate a sensible character.

By good fortune, the two characters we need for this maze (\ and /) happen to be next to each other in the character set, and so a maze is formed with characters 205 and 206. Other systems weren't so lucky, and need constructs like RND(1)*4 to make the magic work. (We'll cover that in the book, too!)

But back to the program! If you run this code on your Commodore 64 you'll notice that my maze is exactly the same as yours! Try it on an emulator. It's the same. It's as if I'd magically predicted what your random numbers would be! I could also show this by asking you to boot up a Commodore 64 emulator right now and typing:

PRINT RND(1)

I should not be able to predict this random number, but I think it will be 0.185564016! However, this is one magic trick where I'm happy to tell you the secret...

...it'll be in the book!

 

Finally, please share this update with your friends and social media contacts to remind them of the content they're missing, and get us closer to our target so we can all have the book with this (and many other) secrets from the retro computing era.

205.5 : It's not just about integers

When we hit 25% I started to make notes for an exclusive update about the number 30. Then I blinked. We hit a Dragon-roaring 32% almost overnight! You folk are epic!

Anyway, so what did I want to say about the number 30? Simply that many of us will know it primarily as an address in Bath. Specifically, 30 Monmouth Street. This is etched in my mind as being the place where Future Publishing were based for the majority of its life, having moved there in January 1990 from their previous location at 4 Queen Street. They produced so many magazines that they probably had one for every computer on the market. (And quite a few of the consolse.) Essentially, if the title had "Format" in it, it was probably Future. Plus, they bought some of the 8-bit magazines, making them resposible for the latter day editions of "Your Sinclair" and "Your Commodore." Also, as we moved into the 32-bit era, they produced the "Official Sony Playstation" magazine which garnered a new generation of fans. Literally, a new generation.

As someone with a diet of computer machines, it reached the point where I even considered asking my boss to transfer my pay cheque directly into their bank account!

Here is me, my Issue 1 of Amiga format, and some of my collection....


 <img alt="" class="doksoft_image_img" src="/images/16822/preview/medium" width="500" height="375">


So, which of their magazines did you collect?

30% - This is the Future!

We are now in triple digits - more than the number of dots on the Acorn owl logo from the BBC Micro!


 <img alt class="doksoft_image_img" src="https://cdn.shopify.com/s/files/1/0728/3615/3620/files/acorn-owl.png?v=1690915947" width="421" height="500">


Wow - thank you all so much.

Please pass on the link so others can join us -

https://unbound.com/books/20goto10/

#retro #80s #8bit #retrogaming #retrocomputing #20goto10

That's 100 (in decimal!)

It's been a fantastic start to the campaign, so could anyone that hasn't posted/tweeted/shared or otherwise mentioned the book please do so, as I'd love to reach 100 supporters by Friday!

Even though this means I lose the magic number 81 from my supporter count!

It was the ZX81, after all, that got me my start in computing. Its name is a logical continuation of Sinclair's previous machine, the ZX80, released in the year (yes, you guessed it) 1980. Its name was also a reference to the Zilog Z80 chip inside it, with some Xtra magic.

Given the original ZX81 only had 1K of memory, and a full screen of text took 768 bytes, you needed to employ some clever tricks to make good use of the machine. Entries 3 and 768 in the book both contain some of these tricks.

81 supporters - can we make 100?

This number is probably the most recognisable integer in all of geekdom - all thanks to Douglas Adams.

But 42, as well as being the answer to the meaning of life is also the ASCII for '*' - which, aptly, is used as the wildcard symbol meaning 'everything'

(It's also 6 x 9 in base 13, XLII in roman numerals, and 101010 in binary, but all are less significant)

42 supporters!

That's 10 people! 10. Not only the number '2' in binary (base 2), but the function key labelled as 'BREAK' on the Acorn BBC Micro which did a soft reset.

At school, we would re-program the break key to recover the previous program in memory, and re-run it. Like this:

*key10 OLD||M RUN||M

What did you do with the break key?

W00t! We hit double figures!

Do you know what secret messages were hidden in Commodore BASIC? Why the highest score possible in Pac-Man is 3333360? That Steve Wozniak set the price of the Apple ][ computer at $666.66? Or why the Amstrad CPC 472 had an 8K chip that was never connected?
From 0 to 2147483647, and from Acorn Atoms to VIC-20s, 20 GOTO 10 takes us on an adventure through the history of retro computers and games consoles – one number at a time.
By following the ‘GOTO’ instructions at the end of each entry, you’ll create a unique journey through this treasure trove of forgotten geek lore and fascinating trivia. With any luck, you’ll discover the number used to grant infinite lives in Jet Set Willy on the Sinclair ZX Spectrum, the reason a single digit might require seven bytes of memory, and how – through numbers – we can understand more than just the internal workings of our favourite retro machines. 
'A book written by a geek for geeks ... It's also a game, a fun and engaging play on the rules of roleplay. I've read and re-read 20 GOTO 10 and constantly find new and strange secrets of retro gaming's past' CreativeBloq
'We have found a book that not only will have something new for you to learn, but the experience is pure nostalgia itself . . . A nice sprinkling of wit and comic timing. We end up with a book that is the best of both worlds, technical information told in an entertaining way' Pixel Addict

20 GOTO 10

20 GOTO 10: 10101001 facts about retro computers

Hardback

Ebook

Signed Hardback

Let us know which obscure retro computer you love and we will make a number related to it appears in the book

Name Your Favourite Machine

Digital copy of ZX Adventure for ZX81 or Spectrum

A3 Cover Art Print

 A guided tour of the The Centre for Computing History in Cambridge by Steven and a trip to the pub afterwards

Guided Tour

Every BASIC program would start with the line '1 REM My Super Game'. We will include the name of your game in a REM statement in the book

Personal Message 1 REM

In the 1980s, every high street store would have a computer running a BASIC program of '10 PRINT "My mate is a moron"; 20 GOTO 10'. You can insert your own message in a PRINT statement that will appear inthe book.

Personal Message 10 Print

Lines numbers in BASIC would usually increment by ten, so you could insert code you missed inbetween them. Consequently, the first such omission would be at line 15. We will include your message in line 15.

Personal Message 15 REM First Change

Typing in listings from magazines was a rite of passage for any 1980s computer kid. So, how about you get your revenge? Send us your listing (of 100 lines or fewer) and we'll hide it within the pages of the book!

Your Game in the Book

Computers never used to be identical beige or silver boxes. Did you decorate, customise, enhance, or otherwise modify your machine to really stand out? If so, let's immortalise your computer by featuring a picture of it in the book! 

Your Computer Featured in the Book

A framed cross-stitch of a ZX Spectrum key, custom-designed and handmade by Lil' Fluffy Crafts. Please indicate an alternate letter, if you desire.

Spectrum Cross-Stitch

An A3 art print featuring the code for David Horne's famous 1k chess programme for the ZX81.

1K Chess Poster

An A3 art print featuring the ZX81 character set.

ZX81 Character Set Poster

An A3 art print featuring the Tandy character set.

Tandy CoCo

An A3 art print featuring the ZX Spectrum character set.

ZX Spectrum Character Set Poster

An A3 art print featuring the ZX80 character set.

ZX80 Character Set Poster

An A3 art print featuring the Dragon 32 character set.

Dragon 32 Character Set Poster

An A3 art print featuring the Commodore 64 character set.

Commodore 64 Character Set Poster

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