Questions tagged [zx-spectrum]

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

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14 votes
2 answers
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What is the size of the border of the ZX Spectrum in scanlines/pixels/bytes?

The bitmap area of the Sinclair ZX Spectrum is exactly 256 x 192 pixels. Surrounding the bitmap is quite a wide border area which is generally just one colour but loading and saving from tape changes ...
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4 votes
1 answer
161 views

Does the .sna snapshot file format for Sinclair ZX Spectrum emulators support a 16k variant

I'm playing with emulator and file format programming again. One of the common game snapshot formats for the Sinclair ZX Spectrum is the .sna format. I know it comes in a 48k format and a newer 128k ...
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10 votes
2 answers
1k views

What was Sinclair's intention with the Microdrive?

The ZX Spectrum was announced with support for both standard cassette tapes and Sinclair's new Microdrive format -- although the latter wasn't released for another 17 months. Given that the necessary ...
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4 votes
2 answers
203 views

Spectrum 128K +2 Power Supply Buzzing and over voltage

I've seen a similar question to asked here but but I'm not sure it fully addresses the issue I'm having. I'm using a PSU the same as this one from the 128K +2 According to this site, this PSU ...
6 votes
2 answers
1k views

Is there a version of Python that runs on a QL, Speccy or a Commodore?

Does any Python port run on any Speccies or Commodores? I am hopeful about QL, since: Based on a Motorola 68008 processor clocked at 7.5 MHz, the QL included 128 KB of RAM, which was officially ...
32 votes
1 answer
3k views

How did the various Soviet ZX Spectrum clones support Cyrillic text?

There may be no one single answer to this question, since the various clones might have done this all in different ways. And of course, some clones do not have the Cyrillic text support at all. I'm ...
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31 votes
1 answer
7k views

Did John Carmack really invent "Adaptive Tile Refresh"?

John Carmack is credited with making fast-paced arcade games like Commander Keen possible on an IBM-PC that had no specialized graphics controllers suited for those, thanks to the "Adaptive Tile ...
8 votes
1 answer
793 views

Why was Carrier Command for the ZX Spectrum superior to the C64 version?

The ZX Spectrum version of Carrier Command has 3D rendering, while the Commodore 64 version, despite a greater amount of RAM, was inferior in comparison. You open the in-game map and there's Google ...
11 votes
1 answer
1k views

Is I/O port 0xFE reserved on the eZ80?

TL;DR Following on from OmarL's comment, to the closed question, Why did the Spectrum Next choose Z80 on FPGA?: But also, the eZ80 is not compatible with the ZX Spectrum because it uses port FE for ...
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4 votes
1 answer
276 views

ZX Spectrum coordinates to bitmap conversion subroutine acting strange

I originally posted this question on stackoverflow, but I wrote a little program that converts coordinates stored in the b and c registers of the z80 into their corresponding memory address for the ZX ...
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9 votes
4 answers
1k views

Compression techniques used in old ZX Spectrum tapes

Many ZX Spectrum games* (and demos) would improve loading time and save space in the tape using rudimentary compression. During decompression, the game would display "decrunching" for ...
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20 votes
3 answers
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 ...
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3 votes
1 answer
213 views

Where can I find a copy of the HiSoft C compiler manual for ZX Spectrum?

I've been able to find the manual for the CPC version of HiSoft C, but not for the ZX. The only ones I could find appeared to have been OCRed, so virtually all of the necessary information was lost. ...
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1 vote
0 answers
173 views

How to save and load CSpect emulator state when emulating ZX Spectrum Next [closed]

I use CSpect emulator for playing a game for ZX Spectrum Next. I wonder whether is possible to save the emulator state to memory and load it in the future in order to have game save/load functionality ...
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9 votes
2 answers
500 views

Did any ZX Spectrum clones use a 16 bit datapath between memory and video generation?

On the Commodore 64, there is a 12 bit datapath between memory and the VIC II: the ordinary screen data, which is in DRAM, and another 4 bits which comes from another SRAM chip which may be paged into ...
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8 votes
3 answers
465 views

Reading data of floppies from a ZX Spectrum Swift Disc

Back in the day when we had a Sixword Ltd. Swift Disc floppy-drive we were ahead of the game on our speccy, allowing us to use 3.5inch floppy disks. See: https://www.worthpoint.com/worthopedia/swift-...
3 votes
3 answers
848 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 ...
9 votes
1 answer
623 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 ...
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6 votes
2 answers
470 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 ...
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7 votes
1 answer
777 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 ...
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9 votes
3 answers
1k 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 ...
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3 votes
1 answer
307 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 ...
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8 votes
2 answers
2k 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 ...
66 votes
5 answers
10k 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 ...
2 votes
2 answers
428 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?
18 votes
1 answer
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 ...
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8 votes
1 answer
356 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 ...
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1 vote
1 answer
483 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 ...
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5 votes
1 answer
332 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 ...
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2 votes
0 answers
357 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 ...
3 votes
1 answer
209 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 ...
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5 votes
2 answers
783 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 ...
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6 votes
1 answer
510 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. ...
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14 votes
1 answer
731 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 ...
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3 votes
1 answer
135 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 ...
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4 votes
3 answers
367 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 ...
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5 votes
4 answers
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 ...
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5 votes
3 answers
573 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 ...
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6 votes
1 answer
225 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 ...
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8 votes
1 answer
594 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, ...
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2 votes
0 answers
113 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 ...
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4 votes
2 answers
451 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 interested in learning about two of the disk ...
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5 votes
4 answers
528 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 ...
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3 votes
2 answers
423 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 ...
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3 votes
0 answers
114 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 ...
3 votes
2 answers
740 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 ...
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66 votes
1 answer
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. ...
11 votes
2 answers
976 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 -------------------------...
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3 votes
4 answers
743 views

Is the ZX Spectrum multithread capable? [closed]

I know the spectrum had the IM2 mode, but can I start multiple threads running simultaneously? Like to play sounds, watch the keyboard, and other tasks who can be runned simultaneous.
11 votes
2 answers
1k views

Is it possible to PRINT AT 23,0 in ZX Spectrum BASIC?

The ZX Spectrum BASIC doesn't (ordinarily) let you print on lines 23 and 24 to allow for user input. Is there a way around this? I found a fairly recent post that suggested I could POKE 16418,0 but ...
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