Questions tagged [zx-spectrum]

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

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6
votes
2answers
100 views

Reading data of floppies from a ZX Spectrum Swift disk

Back in the day we had a sixword swiftdisk we were ahead of the game on our speccy allowing us to us 3.5inch floppy disks. See: https://www.worthpoint.com/worthopedia/swift-disc-interface-zx-spectrum-...
4
votes
3answers
510 views

What are quick ways to load downloaded tape images onto an unmodified 8-bit computer?

There are repositories of tape software available online, for example CPC Power for Amstrad CPC machines. What is the fastest and simplest way to load such games onto an unmodified computer, with the ...
8
votes
1answer
252 views

ZX Spectrum fuse-emulator - how to use loader/multi-file program?

I'm using fuse-emulator on Ubuntu. In a book of type-in programs, some are spread across multiple files. There is a "loader" (usually setting up graphics or some machine code parts) which ...
72
votes
9answers
22k 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 ...
2
votes
1answer
223 views

Why did the Vic-20 need special chips for I/O?

The Vic-20 used two 6522 VIA chips for I/O. I asked why it had two of them but thanks to a comment from Bruce Abbott, I now think that wasn't quite the question I needed to ask. What I really need to ...
6
votes
1answer
597 views

What non-Spectrum computers did Sinclair sell 4 million of?

Reading Alan Sugar : The Amstrad Story, I just came across one of those little oddities that initially manifest as 'huh, wait a minute' and sometimes just mean someone has made a typo, and sometimes ...
6
votes
3answers
1k 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 ...
9
votes
3answers
708 views

ZX Spectrum 48k Power Supply outputting 15V

I got a working ZX Spectrum 48k (issue 6a) with the original power supply. Before hooking up the power supply I tested with my multimeter to see if it was good. The power supply specifies it outputs ...
2
votes
1answer
204 views

Where can I donate Old Mags and Media in bulk in UK?

I am taking advantage of lockdown(s) and scanning/imaging all old media to archive.org, but would like to donate the boxes when finished. A bit like Donating old Computer Shopper Magazines The Centre ...
7
votes
5answers
876 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 ...
6
votes
2answers
1k views

How ZX Spectrum avoided key ghosting

Was ZX spectrum better at handling than later PCs-keyboards without having diodes in its key matrix? I encountered this comment on ycombinator but I fail to understand it. Couldn't be Speccy method ...
63
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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 ...
0
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2answers
259 views

ZX Spectrum red stripes during loading

When we load any game on ZX Spectrum from cassette player... Should red stripes move smoothly for better result or they should be static for perfect result? What is the theory?
22
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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 ...
10
votes
1answer
324 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 ...
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 ...
6
votes
1answer
132 views

Was the Ram Turbo the only 3rd party Interface 2 ROM cartridge interface for the ZX Spectrum or were there others?

One of the original Sinclair peripherals for the ZX Spectrum was the Interface 2 which provided joystick ports and also a slot for ROM cartridges: The cartridges did not catch on though and only ...
16
votes
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 ...
15
votes
4answers
2k 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 ...
1
vote
1answer
298 views

Using Bresenham's circle algorithm (or another alternative algorithm) to draw an arc [closed]

I'm trying to create some graphics function for a ZX Spectrum (Z80) machine in assembler. I already have the basics except for the arc. I know that there must be some way to draw an arc using the ...
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 ...
4
votes
5answers
602 views

Z88DK ZX Spectrum “%f” printf not working

I'm attempting to compile a program in C for the ZX Spectrum using Z88DK. However, I'm facing an issue when trying to use printf to print out the value of a float. The code I'm trying to compile: #...
5
votes
1answer
228 views

Are all 64k x 4-bit ICs interchangeable for Amstrad-era ZX Spectrum 128k +2/+3?

There were 4 64k x 4-bit Integrated Circuit chips in the Amstrad-era Sinclair ZX Spectrum +2 and +3 models. These are known as the +2A, +2B (both +2 "black"), +3 and +3B (also both black cases). I ...
4
votes
2answers
590 views

What file formats were used for binary executable files on later Sinclair ZX Spectrums?

The last official version of the Sinclair ZX Spectrum was the +3, released after the company was owned by Amstrad. It included a 3-inch floppy disk drive as used on other Amstrad computers. But even ...
2
votes
0answers
153 views

Why did the Spectrum Next choose Z80 on FPGA? [closed]

I'm curious to understand why the Spectrum Next uses Z80 on an FPGA instead of something like at eZ80? I would have imagined they would choose the eZ80 since it is still a production part. Anyone ...
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 ...
1
vote
4answers
523 views

Is the ZX Spectrum multithread capable? [closed]

I know the spectrum had the IM2 mode, but can I start multiple threads running simultaneously? In example: can I play a song, while transfering large amounts of data, like in large ldi code blocks? ...
3
votes
1answer
114 views

Where can this “boot.B” file be coming from on this Spectrum TR-DOS disk image?

After working on some tools that parse the TR-DOS disk image format .TRD files for a while I just noticed that one of the game disk images I had downloaded "La Abadia Del Crimen", only has three files ...
4
votes
2answers
179 views

How did the Spectrum clones with TR-DOS and paged memory load and run code files from disk?

I've been playing with Spectrum emulators, their file formats and some reverse engineering tools recently. Thanks to this forum, I was able to parse the TR-DOS disk image format and find the bytes of ...
5
votes
2answers
529 views

Does Sinclair Spectrum BASIC have a maximum length for one line?

I was just writing some junk Speccy Basic programs, more to see how they take up space on the +3's disk layout than to do any actual programming. But I noticed that after editing a program line to ...
6
votes
1answer
352 views

What role does the 4-bit shift register play in the Leningrad video generation?

The Leningrad contains a shift register1, which I believe is loaded with data from the bitmap. This part loads 8 bits in parallel, and shifts each bit out in turn on the rising edge of a clock signal. ...
3
votes
0answers
73 views

How to use Tasword 2 with Esxdos

I'd like to be use the Tasword 2 text editor for the ZX Spectrum to load and save text files on an SD card. Gary Lancaster provides a version of Tasword that uses Residos system calls, but as far as I ...
6
votes
1answer
278 views

Did the Timex Sinclair 2068 and the Sinclair ZX Interface 2 use totally different hardware and software techniques?

Sinclair released an add-on for the Spectrum called the ZX Interface 2 that provided joystick ports and a cartridge slot. It wasn't successful and only a few cartridges were ever produced. In the US, ...
3
votes
2answers
467 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 ...
4
votes
4answers
1k views

How does the Spectrum +3 know whether a disk is bootable or not?

I've been looking through documentation on The Sinclair/Amstrad Spectrum +3 which was the only Spectrum that came with a built-in floppy disk drive. The disk format was based on The Amstrad CPC and ...
21
votes
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 ...
37
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 ...
8
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2answers
1k views

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 ...
5
votes
1answer
527 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 (...
0
votes
1answer
169 views

Do any of the open source Sinclair ZX Spectrum emulators support both TR-DOS and 3DOS?

The number of Spectrum emulators has been growing for decades now so there's quite a lot for different platforms and written in different languages. I'm interesting in learning about two of the disk ...
15
votes
1answer
854 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: ......
12
votes
2answers
666 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 ...
7
votes
2answers
641 views

Why does the .z80 emulator-snapshot format have separate fields for the 8-bit refresh register and bit 7 of R?

I've been looking at the .z80 file format for Sinclair ZX Spectrum games. Most docs discussing the format include pretty much this wording: Offset Length Description -----------------------...
3
votes
1answer
69 views

Is there a Spectrum +3 ROM disassembly available with the addresses of the instructions included?

In my experiments with Spectrum disk formats I've found myself looking into the ROM code a few times. Several Spectrum emulators have built-in debuggers that let me dissassemble and step through the ...
0
votes
2answers
156 views

How do I know where the file directory is stored on a Spectrum +3 disk layout?

I'm trying to parse Spectrum +3 disk images. I only ever had a tape-based Speccy back in the day. The +3 had a built-in floppy drive but was late to the party and not that successful. It had the same ...
6
votes
1answer
129 views

Details of ZS Scorpion port 0x1ffd

There's this page about the ZS Scorpion, and I'm reading about the way bankswitching works. Port 0x7ffd is the same as on western ZX Spectrums, but to double the amount of RAM to 256k and also the ...
2
votes
0answers
83 views

Do we know any estimate of how many Sinclair ZX Spectrums, clones, and compatibles were made in the world?

The original ZX Spectrum was made by Sinclair and then by Amstrad in the UK. There were official versions also in the US, Europe and even India. There were very many clones and compatibles made in ...
5
votes
3answers
310 views

How does DRAM refresh work in the Leningrad?

The Leningrad uses the КР565РУ5 chip, which is the same as a 4164. It contains 64kbits of DRAM, and the datasheet says that each of the 256 row addressed need to be strobed every 4ms. I can see how ...
8
votes
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 ...
3
votes
2answers
186 views

How do I navigate the boot menu in later model Spectrum emulators?

35 years ago I had an original 48K Sinclair ZX Spectrum. I never had any of the Plus or 128K models and practically never even touched one as I moved onto the Amiga quite early. I'm now playing with ...