Questions tagged [zx-spectrum]
For questions about the different versions and products of the Sinclair ZX Spectrum computer
108
questions
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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
189 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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114 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
78 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
453 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
328 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. ...
8
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1answer
145 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
45 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
117 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
937 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
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3answers
229 views
How does DRAM refresh work in the Leningrad?
The Leningrad uses the ŠŠ 565Š Š£5 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
119 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
195 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
73 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
75 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 ...
3
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2answers
133 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 ...
2
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2answers
127 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
60 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
520 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 ...
54
votes
1answer
3k 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
569 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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4answers
472 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
763 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
213 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 ...
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5answers
522 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
votes
1answer
199 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
433 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
votes
2answers
314 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
votes
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 ...
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2answers
739 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 ...
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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 ...
19
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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
373 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
500 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 ...
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2answers
265 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 ...
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2answers
496 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
454 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 ...
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1answer
487 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
437 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 ...
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1answer
253 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
391 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
633 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 ...
11
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3answers
934 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 ...
5
votes
2answers
806 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 ...
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2answers
671 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 ...
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1answer
972 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 ...
