Questions tagged [zx-spectrum]

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

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192 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 ...
7
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3answers
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 ...
18
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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 ...
3
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1answer
142 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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0answers
119 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 ...
6
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1answer
262 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 ...
6
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2answers
137 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-...
3
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3answers
615 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
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1answer
369 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 ...
3
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1answer
261 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 ...
7
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1answer
665 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 ...
9
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3answers
817 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
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1answer
222 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 ...
8
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2answers
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 ...
65
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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 ...
1
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2answers
311 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
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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
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1answer
191 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 ...
1
vote
1answer
398 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 ...
5
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1answer
254 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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0answers
238 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
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1answer
150 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 ...
5
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2answers
643 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
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1answer
370 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. ...
12
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1answer
618 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 ...
3
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1answer
92 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
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2answers
186 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 ...
5
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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 ...
5
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3answers
388 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 ...
6
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1answer
153 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 ...
6
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1answer
374 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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0answers
92 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 ...
0
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1answer
279 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 ...
4
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2answers
253 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 ...
3
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2answers
269 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 ...
3
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0answers
89 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
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2answers
648 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 ...
62
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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. ...
7
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2answers
724 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
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4answers
655 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.
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2answers
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 ...
4
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2answers
410 views

ZX Spectrum scroll waiting for user input problem

I'm trying to compile a C program with z88dk for the ZX Spectrum. Using printf(), when the text hits the bottom line of the screen on line 24 the program stops executing until a key is pressed on the ...
4
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5answers
694 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: #...
4
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1answer
212 views

Checking Old Tapes

How do I check old ZX spectrum cassettes work - the tapes are after all quite old? I am fairly computer savvy (my life is a continual strand from that Speccy to this here Thinkpad - and many stations ...
6
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2answers
484 views

Did loadable levels for ZX-Spectrum games contain only graphics / game data, or executable code as well?

There was a number of ZX-Spectrum games that had loadable levels - e.g. R-Type, Gauntlet, Short Circuit (48k). I wonder if those loadable levels only contained graphics / music / game data for the ...
9
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2answers
442 views

Where to share/who may be interested in IEEE 16 bit half float library for Zilog Z80?

I have recently developed a half-float/16-bit float library (link to Github) for Zilog Z80. It was a part of my project to run some neural network and graphics POCs for ZX Spectrum. The library uses ...
13
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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 ...
12
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2answers
794 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 ...
13
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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 ...
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 ...