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Questions tagged [zx-spectrum]

For questions about the different versions and products of the Sinclair ZX Spectrum computer

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Why did the ZX Spectrum use an internal speaker?

I was surprised to note recently that the Sinclair ZX Spectrum used an internal speaker. I knew the BBC Micro used one, presumably because it was designed to be optionally used with a monitor which ...
9
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How can a peripheral work on both the ZX81 and on the ZX Spectrum?

The ZX Printer was made to work with both the ZX81 and the Spectrum (or rather, the Spectrum was made to work with the ZX81's printer!), but these computers have different expansion ports. What I ...
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2answers
350 views

Why does Sinclair BASIC have two formats for storing numbers in the same structure?

The ZX Spectrum has two formats for storing numbers, both 40 bits, or five bytes. The first is a floating point format, which consists of one exponent byte, and four mantissa bytes. The first bit of ...
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Can a Harlequin ZX Spectrum clone be modifed to run CP/M?

The ZX Spectrum (and therefore the Harlequin) has its ROM from $0000 to $3FFF, while RAM further up to $5AFF is used for the screen (see Memory-Map). As CP/M expects RAM from $0000 upwards the two are ...
6
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2answers
511 views

Why was the Hobbit withdrawn from the UK market?

The Hobbit is a Soviet computer which was built to be compatible with the ZX Spectrum, but with some extensions. For example it has more memory and can run CP/M. The Hobbit had favourable reviews in ...
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1answer
514 views

Inglish parser on the Hobbit (1982 video game)

Most adventure games, to keep the parser simple, might just have some simple rules, which accepts verb + noun or a cardinal direction, and simple things like that. That's almost a CFG, so in Backus-...
5
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3answers
619 views

Why was the Amstrad CPC slow at scrolling

As I understand, neither the Amstrad CPC or the Sinclair Spectrum had any support for hardware scrolling, and arcade conversions struggled compared to the C64 or NES. However, isometric 3D games ...
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2answers
252 views

Can S-100 cards attach to the ZX machines?

S-100 was, as I understand, a very popular way to connect various computer equipment together in the past. Also, from what I understand, S-100 closely matches the same signals as the Intel 8080, as ...
14
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1answer
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What was the reason for the ZX Spectrum's display bitmap layout?

I had a ZX Spectrum 48KB, whose display was a 256*192 monochrome bitmap (plus separate per-block color attributes). I remember the display bitmaps scan lines were laid out in memory in a weird way - ...
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How to protect a ZX Spectrum mainboard from “ageing”?

I have some ZX Spectrums, and in some of them I observe a kind of "disintegration" process of the main board. The connectors break away etc. During the tests one of the boards burned out :(. How can ...
5
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2answers
408 views

Membrane keyboard robustness

Some early computers used a membrane keyboard (ZX80, ZX81, Atari 400), or semi-membrane with minimal keys (ZX Spectrum). This is because it was cheaper than a mechanical keyboard. Intuitively I would ...
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760 views

How compatible is the Leningrad clone with the “original” ZX Spectrum?

In Leningrad they developed a clone of the ZX Spectrum, replacing the ULA by some TTL logic. Some of my speculations: In the USSR, the analog TV sets used SECAM, not PAL, so I imagine that the ...
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Who designed the Sinclair ZX Microdrive and why?

The ZX Microdrive. It is well known that the Microdrive was introduced for the ZX Spectrum along with ZX Interface 1. However, who came up with the idea and the design? Was it Sinclair themselves, ...
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1answer
638 views

Where to buy an 8 bit computer remake? [closed]

I want to buy a remake of an 8-bit computer, e.g. the ZX-Spectrum or c64. Must haves: Modern monitor output(e.g. HDMI) Modern keyboard, no gum keys Modern storage, e.g. SD card or USB stick, etc... ...
5
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1answer
343 views

What was the AMI SAGA and why wasn't it used it all ZX Spectrums?

This page has a note about a chip called AMI SAGA. Apparently it does the same job as the Ferranti ULA, but saves a little circuitry and runs cooler. What was this chip? Some kind of uncommitted ...
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1answer
257 views

ZX Spectrum fault

I was recapping my zx spectrum when after just replacing one specific capacitor it stopped working as before. The picture has multiple horizontal lines over the entire display. This is especially ...
15
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1answer
331 views

How to create a switchless multi-system 2 button Atari joystick?

All systems that use the Atari 9 pin joystick standard make use of the following pins in consistent ways, with each direction and the fire button being connected to the ground pin when pushed. 1 - up ...
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1answer
286 views

Timex Sinclair 1500 and screen “jail bars”

I have tried to eliminate "jail bars" on the screen after UHF mod to video out (based on that: http://zx81stuff.org.uk/zx81/ts1500_video.html) by adding 460uf 16V capacitor between +5V and GND but it ...
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2k views

Native C compiler for Sinclair ZX Spectrum

I am looking for a native C compiler for the Spectrum 128. I would like one which: Has good support for the latest C standard at the time. Is not limited to compiling ridiculously short source code. ...
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4answers
2k views

Which ports are which on this Soviet ZX Spectrum clone?

Today I got my (first) Soviet ZX Spectrum clone. The person who sold it to me had inherited it and had no idea how it worked. It seems to be a home-made clone, rather than a factory-built one. See ...
14
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2answers
960 views

Why does this BASIC program declare variables for the numbers 0 to 4?

On pages 150 to 154 of William Tang's (1982) Spectrum Machine Language for the Absolute Beginner, there are these lines of code. (Note GOTO 9000 is the first non-REM statement in the program). 9000 ...
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ZX BASIC REM statement overhead

Since my other question has been answered and has given me a way to do high-precision timing, I've been experimenting with it a bit. The first thing I did was write a simple benchmark using the FRAMES ...
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4answers
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Make a BASIC TAP file readable on Linux

I am trying to convert my own BASIC TAP files (containing BASIC programs) to text so that they are readable on my Debian GNU/Linux machine. If I open them as is, I get this, which gives me some hope, ...
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Uptime in ZX BASIC

How can I obtain the uptime of a Sinclair ZX Spectrum machine (ZX48, ZX128, or Pentagon clone) via their BASIC interpreter? Specifically, the same value used by RANDOMIZE 0 to seed its PRNG. I would ...
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Understanding INKEY$ in ZX BASIC

The ZX BASIC Manual gives the following little program to demonstrate how INKEY$ works: 10 IF INKEY$ <> "" THEN GO TO 10 20 IF INKEY$ = "" THEN GO TO 20 30 PRINT INKEY$; 40 GO TO 10 While I ...
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ZX Spectrum tokenisation

The BASIC used in the early ZX Spectrum (and also its ZX predecessors) had this weird thing where every single BASIC token was printed onto the keyboard, and for example PRINT or LOAD were entered by ...
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2answers
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What is causing the problem with the RAM in this (claimed) Spectrum 48k?

I bought what was claimed by the seller to be an Issue 4S Spectrum 48k. I tried loading games and some worked while others didn't. Turns out it was the 16k ones that worked and 48k didn't. This ...
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2answers
297 views

Timex 2048 RAM contention ULA/video output

I used to own a Timex TC-2048 ZX Spectrum 48K compatible clone. I programmed it in assembly extensively, both for fun and when learning, and also when testing things for writing my own ZX Spectrum ...
5
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1answer
343 views

Are there any drivers available to use DivMMC on the Spectrum +3e with CP/M plus?

Heading says it all. I have a Spectrum +3 (with +3e ROMs if that makes any difference) with a DivMMC SD card interface. This works fine in +3e mode, but as I like to use the +3 with CP/M plus (...
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2answers
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Spectrum clones 512x192 mode usable text resolution

The original ZX Spectrum has a resolution of 256x192, for 32x24 text. Some later clones add a 512x192 mode. The most obvious thing to do with that is try to display 64x24 text. According to https://en....
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What are tacts in the context of ZX Spectrum systems?

I've heard the term tacts when referring to some hardware capability, e.g. "tacts on one frame" or "tacts per second". I tried Googling this but surprisingly did not find anything relevant. What is ...
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RAM contention and what counts as different banks

From https://en.wikipedia.org/wiki/ZX_Spectrum_Contended_Memory "Contended memory space, on the other hand, is shared between the ULA and the Z80 and the ULA has higher priority. Contended memory ...
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How were the first ZX Spectrum games written?

Being a child of the 80s I loved my ZX Spectrum, did my best to learn BASIC but I felt like the games I was playing (Jetpac, Dizzy, Renegade etc) were perhaps not written using BASIC. I wondered: how ...
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Blue and yellow stripes on the screen when loading from tape on ZX Spectrum

When loading a program from tape on ZX Spectrum you could see those blue and yellow stripes around the splash screen. I might be mistaken but I believe those were even sometimes used for quite ...
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1answer
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What is the maximum BAUD rate for ZX Spectrum tapes?

I've played with various BAUD rate programs that allow you to save most of the RAM into a cassette tape up to around 9600 BAUD. Has anyone written or have a way to write the ram to tape (not ...
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Gamepad triggers main menu in Fuse SDL

I'm trying to set up a gamepad to work with Fuse on Ubuntu. No matter which type of joystick I try to emulate (including None), pressing button #2 (or B in the Sega naming) opens the main SDL menu. ...
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First computer emulator in Windows

I released my ZX Spectrum emulation Wspecem, and GPL sources first time publicly in the Internet at large, the 15th May 1996, for Windows 95. I am quite sure it was the first ZX Spectrum emulation ...
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Did the ZX Spectrum have more original titles than C64?

From casual reading, it seems as though many C64 titles were ported from the ZX Spectrum. Why was this the case? Was the ZX Spectrum more popular? Or easier to develop for?
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Why did POKEing ROM addresses mask port writes?

After reading mcleod_ideafix's answer about the Inves Spectrum+'s "randomize of death", specifically his article on the subject, one thing struck me as odd. From César Hernández Bañó's research: ......
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Why did the ZX Spectrum use edges for its tape storage routines?

Why did the Sinclair ZX-Spectrum use edges for its standard tape storage routines? I can see that frequency modulation was likely necessary in order to account for the inaccurate timings when running ...
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2answers
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Can a USR command damage a ZX Spectrum?

I recently came across this magazine snippet; specifically this section: Aprovechamos para avisar a los usuarios del Inves, que nos ha Ilegado el rumor de que haciendo: BORDER 5 RANDOMIZE USR 4665 ...
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How and why did the ZX Spectrum use so many voltages?

Whilst researching the Zilog Z80, I had found that it accepts a 5V power supply.[2] When looking for information on the ZX Spectrum, I found that its power adaptor produces 9V.[1] Confused, I did some ...
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8answers
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How were Western computer chips reverse-engineered in USSR?

The British ZX Spectrum computer had many clones in the Eastern Bloc. It seems many of them were built using Russian-made chips from the Angstrem factory in Zelenograd in/near Moscow. The Russian ...
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3answers
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Why did the Sinclair ZX-Spectrum use a membrane keyboard?

As a kid, I always had problems with the keyboard. Membrane was hard to come by and expensive. I did not have Kempston/Protec. So I had to play on the keyboard. I was using QAOPMN combination, and ...
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Writting DSK images onto a 3'' floppy for Amstrad/Sinclair computers

For a project I'm working on, I need to write some disks to test on my Amstrad CPC 6128. I've got some 3'' inch blank disks, and all my Amstrad computers (CPC and PCW) have 3'' inch disks, as well as ...
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1answer
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Can polarity inversion damage a ZX Spectrum?

I have a ZX Spectrum+ and it didn't came with it original power supply. I bought a 9 Volts and 2.25 Amps power supply with switchable connectors. There was a mistake and the polarity was inverted, ...
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1answer
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ZX Spectrum+ with SCART Interface doesn't display anything

I have an ZX Spectrum+ that came with a SCART interface (unknown brand, all I know is that it's french and that the blue logo seems to spell "IS"). It didn't came with its original power supply so I ...
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1answer
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Rescuing data from old audio cassettes

In my recent expeditions to the darkest corners of my garage, I've found a load (there's a pun in there somewhere) of old audio tapes containing Sinclair Spectrum code. These aren't commercial titles, ...
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1answer
569 views

Saving the screen on a ZX Spectrum without the prompt

Saving the screen on a Spectrum will typically get part of it obscured with the message “Start tape, then press any key.”: How might one save the screen image from Sinclair BASIC without it being ...
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Transferring data from Spectrum +3 disk to tape/.TAP etc

I've recently found a number of my own programs (very old!) on Spectrum +3 discs, and I'm about to get hold of a working +3. Assuming the discs are readable, I'd like to transfer the programs (mostly ...