I wrote several 'Pac-Man' type games on my ZX81. I wrote a game that measured the speed of my reaction time and then present me with statistics after I'd played a few times. More useful stuff was a bubble sort program so i didn't have to manually alphabetize my weekly spelling list. I also wrote a simple check balancing program which I never used because I was too young to have a checking account. Doh! Not only was there a wobble problem with the 16k extension, but the power plug was always pretty jiggly and would cut power if I pressed the keyboard in the "wrong way" and moved everything slightly. For a while I put the ZX81 in a wooden jig to hold it all steady. Nothing really helped and I lost far more than I ever saved onto tape. But I didn't care cuz it was so incredibly cool to be able to write programs! Great memories......

My ZX81 suffered from the wobbly memory issue. Had a flight "sim" that would take about 5 attempts to load successfully from tape (think it was a 10 or 15 minute tape), I would get so excited when it finally loaded I would bump the machine and have to try all over again :D

@thoperSought

8 жыл бұрын

damien harrison wow, that sounds awful

@letsgocamping88

8 жыл бұрын

Out with the soldering iron!

@greentg10

8 жыл бұрын

damien harrison you old folks have no idea the horrors my generation had to deal with. You ever heard of dial up?

The problem was partly caused by the RAM pack case protruding slightly too far below that of the ZX81, so took repeated flexing loads as people used the keyboard. One workaround that people used was to sit the ZX81 on a book or something, so that the RAM pack just sat in free air. For anyone interested, the ZX81's industrial designer, Rick Dickinson has a set of Flickr galleries containing lots of photos and sketches of his Sinclair product development.

Loved the story that you completely hacked yours to have the ram hard wired in as well as a proper keyboard. The ZX-81 was a fantastic little machine, and it was the price and style that really brought it home.

Ahhh my first computer...hours of typing in games from magazines then hours searching for the typo. Probably changed my world.

@BertGrink

6 жыл бұрын

I know that feeling, my friend! At the time, i didn't have the means to purchase my own computer, so i would spend a lot of time with a friend who had a ZX81, and later a ZX Spectrum, and we kinda shared the work by taking turns at the computer, while the other read aloud the program listing, one command at a time. Then, after an hour or so, we would have a fresh pot of coffee, a little 'smoke', and then swap tasks so that the one who'd just been reading off the magazine would now type on the ZX, and vice versa. Every time we found that an error had crept in, we would then do the same thing "in reverse" so to speak: one would read the listing from the computer screen, while the other double-checked the magazine listing - again taking turns if necessary - until we found the error(s). Man those were great times!

The wobble, in my experience, was caused by the fact that the bottom of the RAM pack sat flush on the surface of the table - I stuck two small rubber feet under the back end of the ZX81, lifting the RAM pack off the table - it was unsupported in this position, but not subject to movement when the casing of the computer flexed.

Oh god i remember this so well! The ZX81 went from not so fast, to incredibly slow with the RAM expansion, and yes, I've lost my fair share of code to the *wobble*. Sexiest computer manual *ever*!

Our ZX81 suffered from the wobbly ram pack. It was super annoying. We taped it to the machine when using.

I would've just 3D printed a nice little holding bracket ;) Seriously I loved the home computer days, computers were so simple and trivial that you could build and hack them -- and you had to in order to get some use out of them. I think that knowledge is what sets my generation (70s) apart from the 90s 'kids' now getting into the IT workplace. They've only learned to do Java or perhaps by the grace of the failing educational system some C++ but most couldn't create a simple computer if their lives depend on it. That's why I rather have electronics students, they still know this and also learn to code unlike BSc Computer Science grads With the VC20 piggy backed the NVRAM chips and only break out CS and solder that onto address line. I must have been 11 when I did that and the reason was that the expansion cartridge cost almost twice as much as just the 16K NVRAM chip.

I loved my ZX81 and I used to suffer badly from rampack wobble but I have to say that blutak did actually solve the issue for me nicely. I put a long thin 'worm-like' piece of it between the rampack and the ZX81 and I don't recall ever having rampack wobble again. So yes, for some of us.. it did the job!

I had a third party memory pack. Never really had a problem with wobble on the RAM pack, but at some point I managed to break the connector and soldered it in place using staples as jumpers. I also got a surplus TI-99/4a keyboard and hacked it so it worked with the ZX-81 after damaging the ribbon portion of the membrane on the original machine.

I realize it may not be suitable for a computer museum, but wouldn't an extension cable from the device to the ram pack solve all of these issues?

I found my dad's zx81 not too long ago, the thing has a much larger (physically) memopack 16k and said packs could be stacked . My father tells me that the wobble was a real problem when u had multiple memopack stacked because they got heavier than the computer itself. Keep up the good videos

Was that in Cambridge?

I'll add to my ZX81 wobble. The ZX81 was my brothers. But years later we sold it at a car boot sale my mum and sister went to. A guy pay £50 for it, late 90s. I thought this was funny as I said "It didn't even work properly because of the RAM pack wiping the data". Little did I know he knew what he was buying, I didn't know that the wobble was a known issue until the film Micro Men.

You have to remember than not all RAM-packs are equal: some shipped without the "Key" in the connector whose purpose was to ensure that the RAM pack would stay in the correct position. If my memory serves me right, Sinclair's own packs shipped initially without that key. If, on the other hand, this key was missing, it could enable the RAM pack to slide sideways a bit, and potentially short out various signals on the edge connector, and it was this behaviour which caused most of those glitches that have now become known as The Dreaded RAM Pack Wobble.

I remember spending hours entering code for a game I got from an issue of Sinclair Programs, only to have my brother jump down the stairs causing the ram pack to wobble when he landed. I went ballistic lol, but I think it was a crap game anyway.

@BertGrink

6 жыл бұрын

Yeah, Sinclair Programs weren't known for publishing a lot of sophisticated programs, but at least they gave a lot of people incentive to "get coding".

Cooler beyond believe!!!

Ours (the 'Murrican port) had a problem which my dad eventually blamed on overheating, so he made a plexiglass box for it to sit on with a fan blowing directly on the underside of the unit.

I don't know if there may have been more than one cause of the RAM pack wobble, but one that i am certain of is this: Some batches of the RAM pcak - presumably the early ones - lacked a tiny plastic "key" in the edge connector to match a cutout in the ZX81 PCB, and as far as i know, the lack of this key would allow the connector to slide a little from side to side; as you may be able to 'see', this could, and often did, result in short circuits, which would mess up the operation of the '81

I took the ZX81 and the RAM Pack out of their cases and screwed the ZX81 board to a piece of plywood with the keyboard membrane just stuck down in front. Worked for years like that. Untill I spilt a drink on it. LOL

I like to see how you enjoy doing your stuff at the Museum.

Reminds me of the ZX80 that I converted the memory to 48K (yep, 48kilobytes = c. infinity). The brilliant designers (no sarcasm intended) threw away 32k of memory space to drive the graphics. So with a bit of extra address decoding, changing some ROM code addressing & adding the static memory I was able to have the 48k! Did crash when a tanker passed though. Chucked it out a few weeks ago due to down-sizing. Built the thing from a kit and first time out I got a screen that was half white and half black,,, Was using a battery charger with no smoothing... Learnt a lot from that machine!

@mikecowen6507

8 жыл бұрын

+Rob Henderson I converted mine to 32K just by replacing the 2K static RAM with a 32K static RAM chip and moving the jumper wire next to the chip. No extra fiddling required. So happy they planned ahead with the PCB layout! An added benefit was lowering the power consumption (and heat) with this simple mod. The thing was rock solid after that. Memories!

@robhenderson490

8 жыл бұрын

Yeah - simple is the right way (best).

At least on the Spectrum, I found that the expansion bus connector on the interface has a tendency to break. The plastic that holds the pins in place can snap, and it if does, interface wobble becomes infinitely more dangerous.

Reminds me of Crystal Castles, a game i used to play on my Atari 2600

If I could go back in time, I would solder it onto the board with a funky bit of 80s rainbow cable. Unless cable length created timing issues..

The TRS80 mc10 was similar, later on, with its 16k RAM pack.

I had one!

I found that a sealed bag of ice on top of the case completely prevented wobble crashes.

Remember the cartridge problems on the NES?

@dixie_rekd9601

8 жыл бұрын

And the n64. .GoldenEye animation bugs... Lol

@vuurniacsquarewave5091

8 жыл бұрын

BlackEpyon If you have the flashing red light/ flashing screen problem, then the anti-piracy verification chip in the cart can't connect to the one in the console, so the one in the console thinks it's an unauthorized game, and resets the system over and over again. But you can fix that by breaking off one of the pins on the 10nes verification chip on the motherboard. There's a plethora of tutorials on KZread.

@MartKencuda

8 жыл бұрын

BlackEpyon Yep, I had a special book that I had to jam in mine for it work. I forgot which book it was, but I remember it was the only one that did the trick. Even similar sized books wouldn't work. I guess my NES just like that paticular one.

@vuurniacsquarewave5091

8 жыл бұрын

Rabid Rabbit Rabbi I have to use the case of an audio tape since I modded the console to get rip of the verfication.

Didn't Jason have a cameo in Micromen?

Superglue worked well for me.

I really wish Clive had gone for bigger enclosures like Acorn did.

Why I must immediately remember on Chris de Burgh ;)?

Get Ashens to come in and wax beige poetic about British home computer joysticks, please.

Evo-Stick!!!

I had a ZX81 - unfortunately I had to wait another 15 years for someone to invent Blu-Tack. Had chewing gum though ;)

Tbh regarding the aesthetics... I would say it still looks pretty good by today's standard..... But say it was never released... if a PC were released today that was basically a tiny keyboard and a load of usbs with a backpack which had HDMI out and WiFi to TV capabilities... Give it some reasonably good specs... 980m a good SSD.. An i5 CPU and say 8 GB of RAM and it would still be a very desirable item in 2015 ...

I hear sometimes in this video the rainbow track in Mario kart, the music and the sounds. Weird.

@sven33r

8 жыл бұрын

At 5:30 or later for example

@eudALify

8 жыл бұрын

+Sven Rahn They're filming in a retro computing museum as show in past videos. There they have retro consoles as well.

@sven33r

8 жыл бұрын

KlaxonCow ok, thanks 😁

@OtobongJaya

8 жыл бұрын

eudALify do you know where the museum is or what I can search to find it?

@letsgocamping88

8 жыл бұрын

It's in Cambridge.

So it's almost like an old raspberry pi, right?

I want to see you ZX81... despite the evil you did to the Microtan 65. You remind me a bit of Martin Freeman which is funny, 'cus he is Chris Curry and didn't own a ZX81 ;)

He's right. We used computers to learn French and Latin, but we used computers.

It looks like the Chromebook that I'm using right now.

My question is why the cartridge was actually put there... blocking the screen.

@kurtu5

8 жыл бұрын

Scratchifier The TV was never on a desk like that. You typically sat on the floor in the living room, and the TV was in a cabinet in front of you.

@WAQWBrentwood

7 жыл бұрын

kurtu5 Yep! I was "spoiled" and had a 5" B&W TV "dedicated” to mine, but yeah, most "home" computers and video game consoles were generally parked on the floor (or coffee table) and were hooked up to the "big" tv (which usually was a floor model console).

The flat keyboard looks very uncomfortable to type on

@WAQWBrentwood

7 жыл бұрын

quorkquork Well, in all honesty we didn't really TYPE on them so much as "poke" on them. The keywords being a one stroke affair made it almost tolerable!😀 The Timex Sinclair 2068 ( US upgrade of the Spectrum) had actual plastic "chicklet" keys, rather than the membrane keys of the ZX-81/Timex 1000 or even the rubber keys of the Spectrum. Made things MUCH better. (and better than these touch screen keyboards of today!)

My RAM pack wobbled like hell. Never lost any data or anything, though.

@WAQWBrentwood

7 жыл бұрын

Nilguiri The Ram pack on my TS-1000 (US version of the ZX-81) had the wobble,but actually only "crashed" once, Damn was I lucky! 🙌.( I still have them!)

@Nilguiri

7 жыл бұрын

Ah! I didn't even know there was a US version. I have no idea what happened to mine. Cool that you still have yours! Cheers.

@WAQWBrentwood

7 жыл бұрын

Nilguiri Yep, Timex distributed the NTSC version of Sinclairs in the US. They also had an upgraded Spectrum model known here as the Timex Sinclair 2068. (a rather nice little machine. I have 1 of those too.👍) I have had other computers during the 1980s, but learned to program in BASIC on those, and therefore been a Sinclair fan since! The small size and lack of moving parts ensured that they survived in pretty decent numbers here despite not selling in the numbers that the more common (and to me less interesting because of it..) Commodores. Peace 😀!

He looks like older Hansi Kürsch

The ram pack was great and worked great until you had spent hours typing in a basic program and suddenly it was all gone, the ram pack lost contact.

SD cards are as bad as ever, but we just live with it.

@MultiPureEnergy

8 жыл бұрын

heroineworshipper I've never had an sd card fail on me, or lose data of any kind. Am I just lucky? Or is this more of a problem with certain products?

@userPrehistoricman

8 жыл бұрын

Jacob Wells Same experience. I've only had issues with SD card readers.

@WAQWBrentwood

7 жыл бұрын

Jacob Wells I've never had one fail. (and I had a couple that survived the washing machine 😜). The biggest problem is that I've LOST (physically..) a few MicróSD cards! (who knows, prolly wound up in the sweeper!)😀

I've never been the first comment before. I'm not sure what to say.

@thoperSought

8 жыл бұрын

Gerard Byrne well, I suppose it happens to everyone sometime.

@fuppetti

8 жыл бұрын

Gerard Byrne The classic is "fist", I believe.

@artemiasalina1860

8 жыл бұрын

+Gerard Byrne "Hello world! "

Brady, I appreciate all the videos. I watch every one. I wish there were more Computerphile videos about modern computer science. I like reminiscing about technology as much as the next person, but what is computer science like now? Modern hardware. Modern languages. Cutting edge technology is being worked on now.

Second!

Any Brits care to chime in on how he said the BBC wanted to get a computer for their show, and the government wanted to get people in computers... The juxtaposition of those sentences tend this yank to think the BBC and the U.K. Government were/are "in bed" so to speak? Here in the states the television networks have always been private companies (expect for the Public Broadcasting Network.) It means that while there may be back pocket agreements between the government and various networks, you will probably hear the story that the government doesn't want you to from one or more networks. Is or was there that concern between what the U.K. Government wanted published and what the BBC said? Thanks in advance!

@zanderwohl

8 жыл бұрын

The BBC is Government funded.

@RetropUk

8 жыл бұрын

The BBC charter is a set a rules which the BBC must follow. One is that the BBC should be educational and that was part of the reason they developed the BBC micro with Acorn computers. (Arm). The BBC is paid for by a licence fee which all people who want to watch live TV must purchase each year. Despite this the BBC is ostensibly 'independent' and the fee allows them to be advert free. All of the hundreds of other channels we get are commercial.

@gl1500ctv

8 жыл бұрын

+scumbaguk +Alexander Lowry Thanks guys! That helps!