Questions tagged [zx-spectrum]

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

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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 ...
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2answers
233 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
108 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
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1answer
205 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
204 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 ...
1
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0answers
137 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
79 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
479 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
337 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. ...
9
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1answer
233 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
54 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
127 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 ...
4
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4answers
976 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 ...
4
votes
3answers
240 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
123 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
225 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, ...
1
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0answers
76 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
108 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
146 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
146 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 ...
2
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0answers
65 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
537 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 ...
59
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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
601 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 -----------------------...
1
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4answers
497 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? ...
10
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2answers
848 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
252 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
555 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
204 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
449 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
354 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
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
751 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
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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
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 ...
20
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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
412 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, ...
13
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4answers
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
516 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
278 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
505 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
492 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 ...
5
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1answer
568 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 ...
11
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1answer
453 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
271 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 ...
3
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2answers
424 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
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 ...
11
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3answers
699 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 ...