What a great idea, using rem statements to contain the assembler mnemonics. Fantastic! 👍 ZX81 was my first computer, but I don't recall seeing anything like that back in the day. Thanks for demoing it!

This is awesome. I'm not sure which I'm more impressed with, that you recovered the program from cassette or that you managed not to get ram pack wobble - so easy to lose everything

The ZX81 was my dream come true, and at the age of 15, I could already enjoy the ZX81 with its entire 1KB of RAM. This is what led me to start writing programs in assembly language. Later, I bought an additional 64KB of memory. I created a Polish<->English dictionary that worked very quickly. It loaded the dictionary from a cassette tape and had a learning function. Those were beautiful times. The limited hardware forced us to write concise code, where every byte and register counted. Today, we have supercomputers in our pockets with 2GHz processors and 8GB of RAM, yet on a touch-sensitive, high-resolution color screen, we still see hourglasses or spinning wheels. I remained faithful to assembly language and today I write programs for Microchip's PIC32. Only we know the joy of moving from an 8-bit Z80 with a 3.5MHz clock to a 32-bit microcontroller with a MIPS core running at 200MHz. Throughout my life, people have always been surprised that I write in ASM instead of C, Python, etc. Thousands of times I’ve heard that assembly introduces bad programming habits, is difficult, lacks process validation, and so on. But I simply enjoy it when you turn on the hardware, the controller works immediately, nothing loads, there's no clunky operating system, the device never crashes, and there's no waiting after pressing a key 🙂 ZX81 to było moje marzenie, które się spełniło i w wieku 15 lat mogłem już się delektować ZX81 z całym 1kB pamięci RAM. To właśnie spowodowało, że zacząłem pisać programy w assemblerze. Potem dokupiłem pamięć 64kB. Zrobiłem słownik polsko<->angielski, który działał bardzo szybko. Wczytywał słownik z kasety. Miał funkcję nauki. Piękne czasy. Ograniczony sprzęt wymuszał pisanie zwięzłego kodu, gdzie liczył się każdy bajt czy rejestr. Dzisiaj mamy w kieszeni super komputery 2GHz/8GB RAM, a na dotykowym, kolorowym, wysokiej rozdzielczości ekranie obserwujemy klepsydrę lub latające kółko. Pozostałem wierny assemblerowi i dziś piszę programy na PIC32 firmy Microchip. I tylko my wiemy jaka to radość przesiąść się z 8-bitowego Z80 z zegarem 3,5MHz na 32- bitowy mikrokontroler z rdzeniem MIPS latający na 200MHz. Przez całe życie ciągle ktoś się dziwił, że piszę w ASM, a nie w C, Pyton itp. itd. Tysiące razy słyszałem, że assembler wprowadza złe nawyki programistyczne, jest trudny, nie ma kontroli poprawności procesu itp, itd. A ja po prosty cieszę się, gdy włączasz sprzęt, sterownik od razu działa, nie ładuje się, żaden kulawy system operacyjny, a urządzenie się po prosty nigdy nie zawiesza i nie ma żadnego oczekiwania po naciśnięciu klawisza :-)

This makes me far happier than you think it would because the ZX81 was the first computer I programmed on over 40 years ago and I kind of forgot how it looked and now I feel it come back to me, so thanks.

You wrote assembler in basic? Wow....😅 Youngsters passion i suppose. I wrote few (thin) notebooks of programs for zx spectrum, only in notebooks because i couldn't afford own computer then and computer interest club was suspended... I sunk in it completely for part of a year even at cost of my grades...

Wow, this brought back some memories for me. I too wrote a little program on the Speccy back in the day. I remember buying (an expensive!) text based quest game creator. It came loaded with a double speed loader, which failed nine out of ten attempts to load. Really frustrating. So I decided to teach myself assembler, and disassemble the loader to unlock the code and save it out for normal speed. I got the Spectrum Rom Disassembly on loan from the local library for six weeks. Figured out how the code worked. Disassembled Matthew Smith's Jetset Willy, and nicked some of his super clever features [like the alternate registers(?)] imbedded in his code. I then spent about six months crafting a small assembly code program capable of disassembling any header loaded into it, including protected headers. The tiny Basic loader loaded a small assembly loader program, which unloaded Basic, and then loaded what followed on tape (which was the main program). I don't remember much of the code. The code was originally set up to disassemble the loader for the game creator that was causing me problems. I quickly figured out how they implemented their copy protection, and rejigged the main program to bypass that, and lay bare the program code. I then saved that out to tape at normal speed, and crafted a short loader to load the main code. It worked very well, as far as I remember. I then turned the program on a few other programs (mostly games tbh) and figured out their copy protection quite quickly. I then redid the code for a third time, so that the program would recognise common copy protection (I seem to remember that they sometimes cheated by putting it in backwards, or split it and had innocuous looking random calls, which were actually invoking the 2nd part of the function), and circumvent it, without necessitating manual intervention from me. I tried it on dozens of games, and it opened all of them. I decided to send it in (annotated) to Crash magazine. It was returned rather promptly, with a nice note saying that it looked quite clever, but that a reader had beaten me to it with a version written in Basic that did pretty much the same thing. I bought the magazine, and scanned the basic code they had included within. I was shocked. The basic code was just that - basic. It loaded basic files, but nothing else. Bear in mind that, like you I was a kid. I couldn't understand how someone who wrote for a gaming magazine (someone I admired) could not have seen that my machine code program was far superior to the Basic program that they had featured in their magazine. My program had done what I set out to do. I was able to use the quest game creator (which was laughable. It used so much RAM to run the code that there was little for the game created), and I had discovered a new found interest in girls. So, I hung up my programmers hat. I still played games, though. And read Crash. About a year later, there was a big headline that one of the major cracking crews had finally cracked the protection on some popular game. You guessed it - that game had been one of the dozens of games that my little program had opened for me the year previous. All of this is hazy, if I'm being honest. It was a long time ago. I haven't given any though to it in more than forty years. But this was a fun little jaunt down Memory Lane. Thank you for that. And for your video.

The colour of the Legs on the Op amp chip U15 means there has been heavy leaking of the caps, and I would replace the capacitors and start from there, and has been said check the voltages on the Op amp there Should be 12v on one side of the and -12v on the other, I have repaired many A600s with sound problems, you just have to be methodical in the fault finding

Thanks❤ I waste my day looking how to connect the same Wi-Fi SD card adapter. I don't know why I remembered someone going through Google and it worked for him. And I see that it's not actually achievable.

One Sinclair Plaza was used for mail orders, 2 Sinclair Plaza for info. According to an article in the Nashua Telegraph of March 12, 1982, the exact address is 141 Canal Street.

I have a question about US QL. I just pick one up and I’ve been having some weird video issues when starting one of the games downloaded of the web the game sometimes will show properly on my RGB Amiga 1084 monitor where I can see the whole screen but sometimes (70% of the time) it will cut off the lower 1/5 off the screen. Can’t figure out what is causing it as my UK QL always shows the full screen. The composite video acts the same way as RGB so it looks like the ULA1 is not providing proper video out and actually when I plug my Sandy super board then the game will run but most of the time the screen goes completely blank. My US QL has some extra rework done in top of the ULA1 with additional diodes and a capacitor which my UK did not have. I wish my UK still worked so I could try another ULA in my US QL but unfortunately the ULA 1 in my UK QL died and I can’t find a replacement for it anywhere. Any help would be greatly appreciated.

Always make sure you are replacing the flat belt with the flat one. And a square belt with the square one

Finger grease is an enemy of the belt and belt path hardware. Belt will tend to slip

If you need to measure the circumvent of the belt just use a thread 🧵 and put it in the belt path.

It's very bad idea to put old sticky belt in contact with a new one. And it is even worse to put that new tainted one in the heap of new belts.

The only part I wanted to see was how you lifted the case off with monitor inside and you transitioned past it 😢

Have you recorded the cassette to a computer as digital audio yet? It might be easier to edit the audio file to get a recoverable program, and it would be a good backstop, each time you put that cassette into a new deck there's a risk of the tape breaking or getting demagnetized or otherwise worn.

Fantastic stuff, and hooray for Toni Baker. She really knew her stuff!

I think the old ROM is the for zx80 but not sure

It's a great book, thanks for sharing😀

Great review. Awesome memories!

i sooooo wanted a QL back in the day looked cool had wafer micro drives it was powerful at that time and claimed to be a step ahead , im old now and i am contemplating getting one to satisfy my younger selfs hunger

Cool. Although I am never used the Timex/Sinclair computers back in the 80s I find it more interesting now to see what people were doing with them. We were a Commodore home so I only had experience with Vic-20 and C64 and later Amiga. In fact although I knew about the North American market Timex computers I did not know they sold the QL in an NTSC version. Where did they sell those computers over here back then? Was it mail order? Very curious how you got on the Sinclair track as that was a pretty rare thing over here in the USA.

@3:03 Q68 review mentioned is at kzbin.info/www/bejne/b3rVpZeLf5qnZ5I

Omg, you got me! 😂

I guess QL needs some kind of double buffering to resolve that flicker

The Amiga version looks great. It's not quite Microprose Grand Prix level, or Lotus Turbo Challenge level, but it's not trying to be. I must try it out. I had no idea the QL was this limited. I thought it was more of a contender. I could conceive of a C64 version, and even a spectrum version running this game faster. Was there any racing game on the C64 that ran slower than this? Yes, many employed tricks, but even Revs with realistic 3d seems more playable than this. Even something as early as the original Pole Position(kzbin.info/www/bejne/nIOaZo2mrK2CeNU) on the C64 plays better than this. If I was so inclined I could hack the graphics on Pole Position 2(kzbin.info/www/bejne/aXzKgJ6pjL-Iiqc) on the C64, changing the main car sprite to a dashboard and have practically the same game as the QL, but faster and more fun.

Hey, if the volume is low and recapping ‘should’ or ‘could’ help… would you not want to get it recapped, just in case? I’ve recapped 6x A600’s or A1200’s in the last 2 years and I’d only say 1 was not leaky… yet. One A600 needed 3 chips and a host of transistors replaced to get it working 100% after very subtle appearing corrosion got to it.

On my A4000 the sound had been working fine right up until it didn't. I knew it needed a recap so I pulled out the Zorro cards and replaced the caps in the sound area and presto, perfect A4000 sound again. I have replaced about 75% of the caps so far.

Check the input voltage on the audio amplifier under load (loud music is playing). If it's wrong, check the voltage regulator under the load. If it doesn't fix the issue, get the schematics and trace the audio path from the analog output back to the digital source, checking the voltages at every checkpoint. If you have the scope - check signals for the waveform.

Heya do you have a PCMCIA NE2000 Ethernet or WiFi PC Card? If so you can use it and the Miami network stack and go online and or network

The amiga version is lite!

The author told how the co-coder of the ST and Amiga versions heavily optimised his code from the QL versions. If only there had been a back port.

Comparing the same game in QL vs A600... is not it a little strange?

i remember hearing that Sony approached Sinclair to incorporate a 3.5" drive in the QL which he refused.. not sure if it's true or an urban legend : )

Fun game

This dumb game entertained a knucklehead quite well. Move back and press up and down them there will be an opening to run for a td. Seems to be a loop expecting you to do something but you trip it up switching between the top 2 or the bottom 2 positions, looking for an opening. The pass opportunity opens up sometimes but the run is where the win is. The td sound is playing in a younger knucklehead's ear. Too fun for the time. The ai is just as dumb today. It only has access to more data at a faster rate. ai is stoopid and that will never change. It can only try to sell crap. That's it and nothing else. Oh and corn. It's good at corn. Lol Suck it ai. Yes, that was another TD while you watch again.

For the keyboard, sometimes the metal contacts where it slides into the connector get some corrosion. You can takenit out and use even a pencil eraser and then isopropyl alcohol and a cotton bud. A600 keyboard cables are known to fail over time. If yours goes, there are modern reproductions.

With regard to interrupts this will depend on the CPU but the operating system will register interrupt service routine addresses for code that will deal with a given interupt. When the interrupt occurs the CPU will deal with it immediately (again the precise details are cpu specific) and run that ISR code. The ISR code will have to deail with the nature of the interrupt and might deal with it then and there or (in the case with windows) they get queued up and dealt with at a different level of the OS through the driver code). This approach allows for drivers to be written to run in user mode rather than kernel mode - user mode drivers don't have access to memory directly and have a virtual address space which makes for a more robust operating system as a user mode driver can't crash the system (in theory).

With Windows the priorities are only used when there is competition for CPU resource - most of the processes on a Windows machine are background processes that only do stuff when responding to an other event (e.g. a timer or when triggered through the actions of another process (like a virus checker). Processes that are active - e.g. your browser still have downtime whilst they are waiting for other stuff to happen - e.g. responses to network requests or perhaps writing to disk etc. The scheduler takes into account whether a process needs to be executed at a specific point in time - the kernel will wake a process back up when a call to the kernel is completed and the process (well thread) can continue. Where you have a thread that is actively doing something where it will keep consuming cpu cycles without creating gaps (perhaps a complex calculation) then this is where priorities come in - theads with higher priorities will be allocated a greater amount of run time compared to processes with lower priority. Realtime is a special priority which was for real time code which is sensitive to timing - an attempt by microsoft to try to lure realtime system designers to use windows rather than dedicated hardware. Setting the wrong type of process to realtime can hang the system as the operating system doesn't get to run it's processes until the realtime process completes.

Has anyone ever tried to cut a VHS tape by hand and replaced it successfully?

I have trust issues with you 😂

I remember having my imagine 3d locking my A1200, but there was a program rhat allow to lower its priority, after setting its priority lower it was like it wasn't even running (it rendered with only a few seconds more but the rest of the computer worked as if ot wasn't running)

Great👍

And, if I remember correctly, size of executable file was only 54KB (Kilo Bytes)! Pretty amazing 👍...

Regarding the keyboard… the Amigas use a membrane keyboard and the membrane can be replaced, new ones are available

FYI PiStorm project now has a driver to use the WiFi on the Raspberry Pi. There is a PiStorm for the A600… running CaffeineOS (Free!) on a PiStorm enabled Amiga really feels modern

Looking forward to it! I recently acquired a used Acer Aspire One ZG5. Maxed out the RAM to a whopping 1.5GB and put 256 GB SATA SSD in it… Dual Booting the Amiga-like AROS AspireOS and Debian 12 32-bit

Let's ditch the USB Stick and go with a new old stock ATI All In Wonder Graphics card with built in TV Tuner plus the software.

It is a shame you can install an AMD All In Wonder Graphics card with integrated TV Tuner.