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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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12
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4answers
2k 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 ...
12
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2answers
669 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 ...
10
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3answers
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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 ...
11
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3answers
1k 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 ...
18
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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 ...
3
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2answers
217 views

ZX Spectrum: What is the “T” state value, with reference to sound?

I have that awesome book - Zx Spectrum ROM Disassembled (correct the title if I got it wrong), where the author wrote about the audio code in the ROM and referring to "T" state, "... T200... T5000, ...
9
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2answers
2k 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 ...
7
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1answer
454 views

Why is ZX80 much faster than Spectrum on Rugg/Feldman benchmarks?

If you look at the results of the Rugg/Feldman benchmarks, shown in this Wiki entry, you'll see that Sinclair ZX80 is much faster than Sinclair Spectrum on all tests despite the fact that both ...
2
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2answers
244 views

ZX Spectrum +2 not saving

I have a ZX Spectrum+2 with the built in tape deck. I can load tapes no problem, when I try to save, I get the border lines. When I try to reload the program I get nothing Any help would be greatly ...
8
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2answers
458 views

Saving screen pixels to string in ZX Basic

I remember programming a ZX spectrum in 128 basic (about 20 years ago). I remember I was able to save a third of the screen into a variable. Something like this: 10 LET A$ = [16384 BYTES starting at ...
9
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1answer
372 views

How did the Sinclair compare on price with the C64 in the UK?

As far as I know, the popular low-end home computers in the UK around the mid-1980s were the Sinclair ZX-Spectrum ("Speccy") and the Commodore C64. I know the BBC micro also had a following, but my ...
3
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1answer
409 views

Z80N multiply compared to MC68000 [closed]

According to this answer (How did multiply instructions work in the various 68ks?) the MC68000 can take up to 70 clock cycles to multiply. The ZX Spectrum Next's FPGA based Z80N has a MUL DE ...
10
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1answer
378 views

Purpose of using REM when running TR-DOS commands in BASIC

When running TR-DOS commands from within BASIC, it's necessary to prefix the command with RANDOMIZE USR 15619: REM: first. I understand the former command, but not the latter. For example, to load a ...
6
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1answer
211 views

How can I input a string in ZX Spectrum BASIC using INPUT and not show the quotation marks?

How can I input a string in ZX Spectrum BASIC and not show the quotation marks on input? I've written a program for my 3-year old daughter to type in some letters, but she keeps deleting the ...
2
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2answers
281 views

Sinclair ZX Spectrum with DivMMC load issue

I use a Sinclair ZX Spectrum Issue 2 with a DivMMC EnJOY! Pro One and the boot process shows no error and I'm even able to enter the file browser but if I choose any game/demo/program I get always ...
22
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3answers
4k 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 ...
11
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3answers
458 views

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 ...
5
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2answers
632 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 ...
4
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2answers
600 views

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 ...
8
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2answers
607 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 ...
15
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1answer
905 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-...
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3answers
1k 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 ...
3
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2answers
328 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 ...
15
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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 - ...
8
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5answers
516 views

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 ...
6
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2answers
457 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 ...
7
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2answers
1k 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 ...
9
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2answers
3k views

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, ...
3
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1answer
1k 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
388 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 ...
1
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1answer
281 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 ...
17
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2answers
551 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 ...
6
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1answer
351 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 ...
12
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3answers
3k 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. ...
31
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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 ...
19
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2answers
2k 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 ...
8
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2answers
633 views

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 ...
10
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4answers
2k 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, ...
17
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5answers
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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 ...
17
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4answers
2k 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 ...
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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 ...
16
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2answers
3k 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 ...
5
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2answers
421 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
404 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 (...
6
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2answers
524 views

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....
12
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4answers
922 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 ...
4
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4answers
653 views

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 ...
67
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8answers
18k 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 ...
20
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2answers
3k 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 ...
7
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1answer
2k views

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 ...