Questions tagged [zx-spectrum]

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

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77
votes
9answers
24k views

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 ...
66
votes
5answers
9k views

Back in 1984 I wrote some games for Spectrum - Will they still be playable?

Back in 1984, I was commissioned to write some games for ZX-Spectrum. They were sold together. To my amazement I found that someone is selling a copy online. I thought of buying it but it is in the ...
62
votes
1answer
4k views

How do I extract the program from the Radiohead "Nude" tribute by James Houston?

One of my favorite videos ever is a tribute to Radiohead "Nude" by James Houston. I have never seen the program in the video available to download, so I've just made an attempt to extract it myself. ...
55
votes
8answers
9k views

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 ...
38
votes
2answers
11k views

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 ...
38
votes
4answers
24k views

Loading ZX Spectrum tape audio in a post-cassette world

My ZX Spectrum 48k seems very resistant to working with audio input. I no longer have any cassette players, so am relying on audio files from digital players. I have been able to save and verify a ...
34
votes
5answers
3k 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 ...
33
votes
2answers
2k views

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, ...
25
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2answers
3k 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 ...
25
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3answers
5k views

Adapting a "modern" keyboard to a ZX Spectrum

Is there a way, such a specific interface adapter, which would allow me to connect a PS/2 keyboard to an original ZX Spectrum? I expect the keyboard to work similarly to the ZX Spectrum itself -- in ...
24
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3answers
1k views

How was polyphony achieved on systems with only one audio channel?

Systems like the ZX Spectrum have simple audio hardware with just one channel. But apparently it was possible to do polyphony on these systems. How was that achieved? The amazing thing with these ...
23
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6answers
3k views

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 ...
23
votes
2answers
4k views

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 ...
22
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3answers
5k views

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 ...
21
votes
3answers
3k views

Was Locomotive BASIC significantly better than Sinclair BASIC?

The Amstrad CPC range of Z80 machines shipped with a ROM BASIC, designed and implemented by Locomotive Software. The most well known competitor was the Sinclair ZX Spectrum, also a Z80 machine, with ...
21
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3answers
2k views

How did "full memory" Spectrum tape copiers work?

There are some tape copiers, such as LERM that claim to be able to copy tapes which contain software that takes the full 48kbyte of RAM. However, this seems impossible on a Spectrum, when the whole ...
20
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3answers
2k views

Documentation for the ZX Spectrum ULA

I am writing a Spectrum emulator, however I am finding it difficult to find official or reliable information about the ULA, its functioning and its pins. Are there official sources documenting its ...
19
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6answers
3k views

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 ...
19
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5answers
2k views

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 ...
19
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3answers
2k views

Is there a list of space-saving techniques for representing constants?

Since numbers in ZX BASIC are always floating point and take up 5 bytes, it's often possible to save space when representing integers by using several tokens, which take up 1 byte each. I know of COS ...
19
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2answers
2k views

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 ...
18
votes
1answer
5k views

Could Pac-Man be replicated perfectly on the ZX Spectrum?

We all know that various ports of Pac-Man exist but my question is just for one specific computer. Could the Spectrum, with time and proper knowledge, run the Arcade version of Pac-Man despite it's ...
18
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3answers
5k 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. ...
17
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4answers
1k views

Are there any ZX Spectrum applications (mainly games or demoscene productions) that use a port other than $FE to access the ULA?

Although it is widely known that the ZX Spectrum ULA answers to any request to an even I/O address, all documentation state that the official port number to use should be $xxFE (where xx is any 8 bit ...
17
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2answers
4k views

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 ...
17
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3answers
1k views

The smell of a computer while unboxing it

Don't know if this is on-topic, but I will give it a chance to go. If you feel this is off-topic, act accordingly. Recently, a discussion has started about the feelings associated to the unboxing of ...
17
votes
2answers
863 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 ...
17
votes
1answer
1k 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-...
16
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7answers
3k views

What should be the waveform for ZX Spectrum tapes?

I am digitizing about 40 tapes with programs for the ZX Spectrum. I am somewhat puzzled by the waveform after digitization. The signal of most cassettes is meander-shaped. One of the cassettes can ...
16
votes
2answers
6k views

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 ...
16
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3answers
1k views

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 ...
16
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6answers
2k views

Did scanlines appear on the ZX Spectrum screen?

I used played Spectrum games as a child. According http://scanlines.hazard-city.de/ and http://www.zxdesign.info/vidresearch.shtml, the Spectrum 48K emitted 50Hz half-resolution full frames, instead ...
16
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4answers
2k views

Powering up my ZX Spectrum

I have also found a nice ZX Spectrum laying around. It needs a power source of course to run but there seems to be none that can be used to power it. Google doesn't seem to help and I would love to be ...
16
votes
1answer
2k views

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 - ...
16
votes
1answer
1k views

Measuring frame length on the ZX Spectrum

I've seen some small utilities for the ZX Spectrum, such as FUSETEST and MINFO, that report the number of T-states per frame. I can see these utilities don't rely on ROM checksums or anything like ...
15
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4answers
3k views

Why did some Spectrum games need LOAD "" CODE?

Most ZX Spectrum games were loaded from tape, and the traditional way of starting the loading process (at least in the 48K era) was to type LOAD "" and then start the tape. This would normally load ...
15
votes
1answer
959 views

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: ......
14
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4answers
3k views

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, ...
14
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4answers
1k views

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 ...
13
votes
4answers
3k views

Accelerators for Z80 micros?

I am familiar with the various accelerator products that were developed over the years to improve the performance of popular 6502 home micros. A short list of the particularly well known devices would ...
13
votes
3answers
2k views

Why does this ZX Spectrum machine code "Hello World" routine not produce the expected result?

This is probably an easy one, but I'm stumped. I want to run this ZX Spectrum Hello World routine on my Sinclair ZX Spectrum 48k. I'm going to describe all the steps I took so it's easier to see ...
13
votes
1answer
2k views

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, ...
13
votes
1answer
631 views

Did the Samsung SPC-650 have any hardware or firmware differences to the genuine Sinclair Spectrum+?

There was a clone of the Sinclair Spectrum+ in South Korea called the Samsung SPC-650 that looks identical to original British version with just an extra model number/logo. It even retains the ...
12
votes
3answers
1k 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 ...
12
votes
3answers
2k views

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 ...
12
votes
2answers
797 views

Did the Oric-1 improve on the Spectrum's keyboard?

So I've been whiling away some of a quiet Saturday night reading up on an early eighties computer called the Oric-1, which seems to be a curious little machine that has been largely unsung; moderately ...
12
votes
2answers
704 views

Why did Amstrad choose such bank combinations for its all-RAM mode in +2A and +3 Spectrum computers?

The +2A and the +3 versions of the ZX Spectrum, made by Amstrad, had a new banking mode, called "special". This banking mode is entered by setting bit 0 of port 1FFD. When active, two bits from this ...
12
votes
2answers
868 views

How do I replace a ZX Spectrum 48k keyboard membrane?

I have a ZX Spectrum 48k on which the keyboard membrane has cracked over the years and, while the Speccy itself is operational, has rendered the computer unusable. I am now in possession of a ...
11
votes
3answers
2k views

What format is the (Timex) Sinclair ZX Spectrum SCREEN$/.SCR file

What format is the (Timex) Sinclair ZX Spectrum SCREEN$/.SCR file and how is the fore/background and attribute data encoded within this format?
11
votes
4answers
2k 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 ...