[HN Gopher] The ZX81 Turns 40 ___________________________________________________________________ The ZX81 Turns 40 Author : ggambetta Score : 119 points Date : 2021-03-07 07:53 UTC (15 hours ago) (HTM) web link (www.theregister.com) (TXT) w3m dump (www.theregister.com) | j11m wrote: | My grandfather, who worked in electronics and ham radios, bought | one of these. He didn't care for programming and gave it to me. | "Here's the computer, the manuals, the wires and a black-and- | white TV. You might like this. I didn't." | | I grew up in a modest-income household and didn't get a lot of | good guidance from my parents. My dad literally told me that I | should not learn to work with computers because they would "think | for me". | | I learned it despite my father. I consider his hand-me-down gift | as one of the most significant gifts in my life, as building | computer software has been my career for over 25 years. | rwmj wrote: | My first computer - I still have it although it needs | restoration. We didn't know at the time it was so limited because | there was nothing to compare it to. | | The author of the programming manual - Steve Vickers - could be | thought of both the first and last person to formally teach me | computer science, since I eagerly followed the entire manual back | in 1981, and then 15 years later I took his notoriously difficult | and impenetrable course on Mathematical Structures at university. | amelius wrote: | I grew up on the Apple ][ but I can certainly relate to some of | the stories here. | | Except now I hate Apple for turning into such a snob company :( | Theodores wrote: | Imagine a Sinclair laptop. With options for a monochrome screen | and a flat membrane keyboard. There would be no internal | battery, just a wedge shaped power brick. The case would be | black. RRP? 99.99 | nickt wrote: | The Z88 came pretty close to that, though the keyboard was | better. It's 34 years old, wow. | | https://en.wikipedia.org/wiki/Cambridge_Z88 | sys_64738 wrote: | I have a Timex Sinclair 1000 in my basement (the 2K USA version | of the ZX81). Commodore had the largest warehouse of these in | North America by 1984. | nickt wrote: | > Commodore had the largest warehouse of these in North America | by 1984 | | That sounds like a story, have any more details? | TMWNN wrote: | sys_64738 is referring to Commodore running a tradein program | for $100 off a C64 with any computer or videogame console. | People purchased the Timex Sinclair for $45 solely to trade | in (https://dfarq.homeip.net/wp- | content/uploads/2020/08/timex-co... supposedly, Commodore | used them as doorstops. | nickt wrote: | Thanks! I had no idea. | sys_64738 wrote: | The C128 from 1985 had a Z80 built into it. Where did those | come from I wonder? | timbit42 wrote: | Bil Herd claims he took the Z80 used in the prototype | C128 from one of the ZX81 doorstops. | nickt wrote: | Great point. I just had a look in my C128 and they are | just regular branded Zilog Z80s. I sure there's a story | there too... | elvis70 wrote: | First computer of the family, received as a kit. My mother, my | father and I took turns copying listings from books and | magazines. I remember we were very enthusiastic and fascinated by | this machine. The first words I achieved to type on it were swear | words. | | My phalanges still remember it! | | Having said that, I had an instinct of repulsion at the sight of | the RAM pack on the photo. | uncledave wrote: | Ah the RAM pack. This resulted in a life of wiggle wiggle crash | crash. | | I managed to get my hands on a beeb eventually. Thank goodness. | steverb wrote: | This is the computer I learned to program on (the TS1000 US | Version). The manual for it still has place of honor on my | bookshelf. | analog31 wrote: | I heard through the grapevine that K-Mart was blowing out a | Timex/Sinclair computer for 30 bucks, so I hopped on my bike and | brought one home. I used it to program a formula from a book | about loudspeaker design, to make a speaker for my electric bass. | My program spit out a bunch of numbers, which I graphed by hand, | but I was in heaven. (Turns out looking back, I'm pretty sure the | formula in the book was wrong). | | I couldn't get the cassette interface to work, so I begged | everybody in the house not to unplug the computer until I was | done with my project. A few weeks later my mom got a Commodore | VIC-20, which of course had a full keyboard, so it became my | computer of choice until I finally got a more elaborate machine | in college. | nickt wrote: | In terms of ROI, the best PS69.95 I ever spent (I still have the | receipt from WH Smith). It wasn't the first computer I ever used, | but it's the first one I ever owned at age 9 and it led me down | the path that'll be familiar to many here... I'm glad I still | have it, and the Spectrum and Amiga's that followed. | | Incredibly, the ZX81 hardware and software scene is still alive. | You can get parts for it quite easily, including keyboard | membranes, molex connectors for the membranes, replacement jack | sockets. SellmyRetro is a good place to start [1]. The composite | video out is a simple and worthwhile modification. | | The ZXPand+ interface [2] is an expansion unit that has a 32k RAM | upgrade, SDCard slot, AY sound, hi-res support and a 9-pin | joystick interface. | | The zx-key is a replacement keyboard, and David Stephenson tells | a great story about its creation [3]. | | And games too [4]. I always loved the design of the cassette | covers, and cronosoft guys have done a great job reproducing | them. I reminded how good an imagination you needed playing these | games back in 1981! | | [1] https://www.sellmyretro.com/category/retro- | computers/sinclai... [2] http://www.rwapsoftware.co.uk/zx812.html | [3] http://www.zx81keyboardadventure.com/search/label/ZXKey [4] | https://cronosoft.fwscart.com/SINCLAIR_ZX81/cat5357733_41194... | criddell wrote: | I asked for a TI-99/4A because that's what my best friend had | and we would make games and share them with each other. | | When I think back to the microcomputers of the early 80's, I'm | kind of astounded that they sold in the numbers they did. They | were pretty useless. | TheOtherHobbes wrote: | They were imagination amplifiers. The computer itself didn't | do much so you had to fill in the gaps by imagining the | things it wasn't doing - often guided by some exciting cover | art on books and games packaging. | | You could also expand your imagination by thinking of the | things you might do if you worked hard at it, or if it was | only slightly bigger/faster/better. | | Modern computing is the opposite. It does so much it doesn't | leave any gaps for your imagination to fill - the creative | equivalent of a distracting wall of noise for you to consume. | ddingus wrote: | Great phrase! | | In my view, this is one of the appeals very low resolution | graphics can bring to the table. | | Code does not have to do much, which helped the fun alone. | | See the blue ones? Yeah, collect those. Reds are baddies... | | Or, on a ZX81 or PET, it was just shapes. | | Still that was enough. Let the mind run wild! | nickt wrote: | > imagination amplifiers | | Thank you for that, yes - that explains them perfectly. | Probably explains why I've always felt more at home in the | terminal. | bm98 wrote: | 1982 Atari 800 here (was 8 years old at the time). I remember | thinking the same thing at the time. When we first bought the | thing, there just wasn't much I/O beyond the tape drive (and | later the disk drive), and therefore the things we could do | seemed very limited. It wasn't until we got a printer (a Star | Micronics SG-10 dot matrix tractor feed) and a 300-bps modem | that the world really opened up! | rootbear wrote: | I never had any of the classic 8-bit home computers. I built | a CP/M system from an Ampro Little Board, connected to the | Heathkit H19 terminal I put together. The downside of that | was little commercial software, but I mostly used it for | accessing the University VAX 11/780. I follow a bunch of | retro-computing Youtubers now and I feel like I missed out on | something. My best friend had an Apple II and was always | suggesting I get one. He still has it. | neilv wrote: | The TI 99/4A was great in some ways, especially because at | one point TI was dumping or loss-leadering them, so, IIRC, a | family eventually could pick up one for $50. | | Though, one of the big drawbacks of it, relative to some | other home computers of the time, is that you couldn't really | take advantage of the overpowered graphics processor using | the TI BASIC that came with it. To use assembly language, you | needed a rare add-on. IIRC, there was also an Extended BASIC | cartridge, which was also rare. | | But the TI 99/4A wasn't useless -- you could do a lot with | character set definition and sound from the stock BASIC, and | it came with a great introductory book that taught you enough | to get started creating with those. With some creativity, you | could do a lot with that. (Flight simulator? So long as you | didn't bank too fast for characters to be redefined for the | horizon, maybe. :) | | I recall the family going to some dingy school-supply audio- | visual store to look at their Apple computers. They had the | //c and I think //e on display. Then my parents saw the | price, and I could tell it was way too high. So, TI 99/4A it | was, plugged into a portable little B&W TV that my dad bought | from a guy at work. (Until I made enough money lawn-mowing | and babysitting and various money-making schemes, and a | kindly computer store owner gave me what had to be a below- | cost deal on a semi-compatible PC.) Apple got some pre-Mac | glory for microcomputer innovation, but I suspect that the | _non_ -Apple $100-$250 home computers reached more families | at the time. | | Having _a_ computer was infinitely better than _no_ computer, | and the TI 99 /4A was a good little imperfect computer. | spongeb00b wrote: | Even Blu-Tack for holding on the RAM expansion is still | available to buy (sorry, too hard to resist) | nickt wrote: | Real coders use Velcro ;) | | [EDIT] actually, the Memotech units shipped with a piece of | velcro to eliminate wobble. I think that Memotech kit had a | great aesthetic. | | https://www.nightfallcrew.com/27/09/2013/memotech- | memopack-1... | [deleted] | YZF wrote: | ZX81 -> ZX Spectrum -> Atari 520ST | | It wasn't the first computer I used but it was the first | computer I owned. I still have all the hardware somewhere | (including minutia like the ZX Microdrive sitting on my desk | right now), I have some books as well ;) | TacticalCoder wrote: | > I'm glad I still have it, and the Spectrum and Amiga's that | followed. | | I wonder how many of us still have them all... I probably sound | like a broken record at this time but I still have my Atari 600 | XL, Commodore 128 (which I was only using in C64 mode) and | Commodore Amiga. | | The 600 XL and 128 are still working and the Amiga is probably | easy to fix. | cesaref wrote: | I ditched almost all my old computers as I upgraded, but i've | still got my ZX-81 with a dk'tronics graphics rom, that was a | killer combination in 1982 or whenever! | | The ones that have left the building include C64, C128D, | Amiga 1000, Amiga 500, before I got my first 'proper' | computer, a Mac IIcx which I had for many years running | Logic. I'd like to say those were the days, but actually i | get much more done and have more fun with modern computers, | it's really just nostalgia for simpler times... | TacticalCoder wrote: | Oh totally: I'm not using them and much prefer my modern | setup and its 3840x1600 monitor ; ) | | I just found these old machines of mine in a garage during | the first Covid lockdown and decided to try them out and | found out they were still working (still had an old CRT TV | laying around). | vram22 wrote: | I agree about the nostalgia, and will also add (differing), | that at least in some ways, those were more fun times ... | because the overhead of all this modern complexity | (although it sure does confer greater features and power), | does kill off some of the fun. | FabHK wrote: | > Incredibly, the ZX81 hardware and software scene is still | alive. | | Indeed. Here the German ZX81 User group: | | http://www.zx81.de/ | | http://www.zx81.de/zxcms/English.html | | They've managed to turn a ZX81 into a web server: | | http://zx81-siggi.zx-team.org/ZxTeaM | | (I hope it survives being HN'd...) | MaxBarraclough wrote: | > (I hope it survives being HN'd...) | | Looks like we sunk it. | nickt wrote: | Again! | | https://news.ycombinator.com/item?id=25638936 | cr212 wrote: | I think it was the ZX81 (and later the Spectrum) where my brother | and I had it hooked up to the mains on my parent's boat. The | problem was there was only one 12V battery (via a voltage | regulator) which not only powered lights and our computer, but | also served the engine. If we were sailing and the wind dropped, | we established a protocol where my Dad would have to give | sufficient notice for us to save whatever we were working on to | tape before he started the engine, as the starter motor drew | enough current to dip the voltage below the 9V the ZX81 needed, | thus causing it to crash. And of course, RAM wobble wasn't helped | if there were heavy waves. It's amazing what we put up with just | to get some computing time. | davidrupp wrote: | I did my first programming on one of these, translating text | games (bitmapped graphics were possible with the 16K RAM pack, | but I didn't have one of those for a long time) from a book of | them written for the TRS-80. The combination of having to | translate between dialects of BASIC and having to "translate" | game features to match the ZX81's reduced capabilities was a | great practical exercise in inventiveness and perseverance. I | particularly remember a Star Trek combat game that ended up | taking up so much of the onboard RAM (one whole kilobyte!) that | it started eating into the screen buffer, reducing the number of | lines the computer could display. I think I ended up with one or | two lines of text telling me what was going on, and one line of | input for my next command. | | Today, I work at Amazon as a senior software engineer. I believe | having access to this affordable[1] computer as a teenager helped | make that career path possible. | | [1] The TRS-80 and other contemporaries of the ZX81 were very | not-affordable to my family at the time. | canada_dry wrote: | Speaking of modified ZX81's... I re-wired a full sized keyboard | (I think I was ~15 at the time) to replace the original [i] | | [i] https://i.imgur.com/MpoQP4u.jpg | | The ZX81 along with the Z80 microprocessor book from Radio Shack | [ii] were the _gateway drugs_ that focused my career direction! | | [ii] https://www.cpc- | power.com/cpcarchives/index.php?page=article... | | I'm retired now, but my career went from jr. programmer (in | banking) thru to executive level IT management. A great ride | thanks in large part to that inexpensive UK computer! | nickcw wrote: | I just posted a pic of my highly modified ZX81 here | | https://mobile.twitter.com/njcw/status/1368566103933337603 | | In honour of the #zx81 40th bday I got mine out the attic. I | modified it heavily to have external keyboard, programmable | character generator and easy access to swap the ROM. I killed it | trying to upgrade to 48k RAM but I haven't the heart to dispose | of my first computing love! | | In those days I obviously had no fear cutting into the case and | soldering stuff on the motherboard! I'm not that brave any more. | nickt wrote: | Looks very retro cyberdeck! | JNRowe wrote: | What is the keyboard in your photo? The lack of oversized keys | has me confused. | | Also, love that it is a 3,284,741 byte image of a ZX81. And the | ,/< because -- presumably -- a dog ate your 1 ;) | nickcw wrote: | It is a cast off relay keyboard - easy to wire up to the | ZX81. I don't recall where it came from, but I don't think it | ever had a 1 key as was common on typewriters back then (you | just used l instead). | JNRowe wrote: | Oh, I had absolutely no idea about that. I naively assumed | the current number row was original. You've sent me down a | rabbit hole that so far includes using f and L to produce a | PS too, thanks! | | For others like me the qwerty page1 has some info, and some | examples of original layouts without a 1 key2. | | 1 https://en.m.wikipedia.org/wiki/Qwerty | | 2 https://en.m.wikipedia.org/wiki/File:QWERTY_1878.png | virgulino wrote: | The first computer I saw [0], and the first computer at home [1], | were Brazilian clones of the Sinclair ZX81. | | That's where I learned to program, in Basic. It changed my life. | | Thanks Sinclair. | | 0 https://en.wikipedia.org/wiki/TK82C 1 | https://pt.wikipedia.org/wiki/CP200 | | [ https://news.ycombinator.com/item?id=26360746 ] | trynton wrote: | According to something I read somewhere. The ZX81 floating | routines did incorperate some unique math: | | (2^32) - ((2^32)-1) did not return 1 | | And the group of Cambridge mathamaticians that wrote the ROM | turned out to be one man. | | "ZX81 ROM Assembly Listing" | | https://www.tablix.org/~avian/spectrum/rom/zx81.htm | rwmj wrote: | I just tried it on the ZX81 online emulator: | http://www.zx81stuff.org.uk/zx81/jtyone.html | | You have to type the following sequence of keys: | P [Shift]I 2 [Shift]H 3 2 [Shift]O - [Shift]I | [Shift]I 2 [Shift]H 3 2 [Shift]O - 1 [Shift]O | Enter | | which should appear as: PRINT | (2**32)-((2**32)-1) | | It prints 0 which is not the expected answer! (The 0/0 at the | bottom of the screeen is an OK message, the answer is printed | in the top left corner). I think this isn't necessarily a bug, | it's because the computer used something similar to modern | single precision floating point. | | Also try this (SQR is entered as: [Shift]Enter H): | PRINT SQR 0.25 | | On the emulator it looks like the bug has been fixed, but on | early models of the real hardware it would give a completely | bogus result. | | I think what was interesting was it used a kind of bytecode to | run maths routines (similar to the Apple II's SWEET16 code). | zokier wrote: | 0 is actually what I'd expect as an answer. Even on very | modern Python you get In [1]: 2.0**64 - | (2.0**64-1.0) Out[1]: 0.0 | | Thats how floats behave like with operands that differ | greatly in magnitude. Also this In [2]: | 2.0**64 == (2.0**64 - 1.0) Out[2]: True | trynton wrote: | > 0 is actually what I'd expect as an answer. Even on very | modern Python you get | | Given a four byte mantissa, it should be 1 for anything | under and equal to 2^32 and 0 for anything over 2^32. | Instead it outputted some random number. A bug in checking | the flags or some-such. Or maybe a bug in the float to | string routine. | zokier wrote: | The sign takes one bit off the mantissa. | anthk wrote: | "1" in Scheme: >(- (expt 2 64) (- (expt 2 | 64) 1)) 1 | | http://people.csail.mit.edu/jaffer/SCM.html | trynton wrote: | According to the link to ""ZX81 ROM Assembly Listing"", it | used a "FORTH-like, stack-based language.". Amazing all the | same how they managed to squeeze so much out of so little. | klelatti wrote: | One of the things that distinguished the ZX81 from its | predecessor the ZX80 was the fact that the screen didn't go off | when your program was running, which made it much more useful. | The CPU was still driving the screen but interrupts ensured that | it was doing so when needed so actual code execution was limited | to times when it wasn't needed for the screen. | | This of course made it exceedingly slow. Not helped by the fact | that the BASIC - squeezed into 8k - was also very slow. | | You could write a surprisingly big program in the 1k RAM though | due to the fact that all the BASIC keywords were stored as one | byte - and had to be entered using one keypress. Which given the | quality of the key (not actually keys) board was a relief. | | Truly a machine built down to a price, but with considerable | ingenuity! | forinti wrote: | You could, for 170 pounds, get an Acorn Atom. It had 2KB of RAM | (twice as much!), a proper keyboard, an excellent BASIC, and a | video chip. | klelatti wrote: | Wikipedia says that would be over PS700 in 2019 money - too | much for a 15 year old! | | Besides the PS170 Atom only had Integer Basic - we had real | (sort of) floating point. | | I'm still jealous of anyone who had an Atom though. | [deleted] | andromaton wrote: | And the A in ARM stands for Acorn. And the ARM1 was based | on a Berkeley design, now on version 5 (Risc V). | Connections, connections everywhere. | ourcat wrote: | I had one of these at age 10. I still have it (at age 50) and it | still works. Also the printer and a roll of paper. | | Whenever people ask me what my earliest memory is, I say the 16k | RAM Pack. :) | Theodores wrote: | My inner nine year old envies you for having the printer and | paper. | | I will memorise your earliest memory joke. | Twirrim wrote: | I'm 40, I vaguely remember my parents had one at some stage, | and I'm reasonably sure it had the 16k RAM pack, but the first | I really remember is the ZX Spectrum with the 48K ram, and | rubber keys. First thing I ever programmed, though mostly I | wanted to play Chucky Egg, Manic Miner, Granny's Garden etc. | ourcat wrote: | I never had a 'Speccy'. | | Some old friends of mine wrote a song ages ago about the | effect those machines had on us all, called "Hey Hey 16k" - | https://www.youtube.com/watch?v=Ts96J7HhO28 | elvis70 wrote: | The 16k RAM Pack, a life lesson in itself. | nickt wrote: | I recently restored a ZX Printer, bit of a pain but mostly | because the belts disintegrate on touch. You can buy new ones | though [1] and you see them on eBay too sometimes. | | Worth the resto for the wonderful noise they make! | | [1] https://www.sellmyretro.com/offer/details/zx-printer- | replace... | zeckalpha wrote: | I have a photo of my grandfather with a ZX81, though I never saw | him use it. By the time I was around, he had an Apple //e and an | IBM PS/2. | tyingq wrote: | I remember them being wildly popular at first, because they | were so much cheaper than other 8 bit computers. Then, price | wars made computers with more memory and a better keyboard more | competitive, and you started seeing much less of the ZX81. | dcminter wrote: | If like me you have fond memories of the ZX81 (though not perhaps | of the keyboard), then you might find this print interesting: | | http://www.alisoneldred.com/john-harris/fine-art-prints-1/sc... | Theodores wrote: | Good find. For me the artwork looks better as the manual with | the red writing. | dcminter wrote: | I found it a while back and couldn't resist. I'm having it | framed at the moment. I have the original manual from my own | ZX81 (from which I taught myself to program) so I get the | best of both worlds there. | | I plan to have the print visible in the background on the | webcam for work meetings to earn a bit of nerd cred. | Theodores wrote: | It deserves to be licensed as a desktop wallpaper in Ubuntu | or another operating system. ___________________________________________________________________ (page generated 2021-03-07 23:01 UTC)