Questions tagged [zx-spectrum]
For questions about the different versions and products of the Sinclair ZX Spectrum computer
81
questions
12
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 ...
12
votes
2answers
669 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 ...
10
votes
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 ...
11
votes
3answers
1k 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 ...
18
votes
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
votes
2answers
217 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, ...
9
votes
2answers
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
votes
1answer
454 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
votes
2answers
244 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
votes
2answers
458 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
votes
1answer
372 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 ...
3
votes
1answer
409 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 ...
10
votes
1answer
378 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
votes
1answer
211 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 ...
2
votes
2answers
281 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
votes
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
votes
3answers
458 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 ...
5
votes
2answers
632 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 ...
4
votes
2answers
600 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 ...
8
votes
2answers
607 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 ...
15
votes
1answer
905 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-...
5
votes
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 ...
3
votes
2answers
328 views
Can S-100 cards attach to the ZX machines?
S-100 was, as I understand, a very popular way to connect various computer equipment together in the past. Also, from what I understand, S-100 closely matches the same signals as the Intel 8080, as ...
15
votes
1answer
2k views
What was the reason for the ZX Spectrum's display bitmap layout?
I had a ZX Spectrum 48KB, whose display was a 256*192 monochrome bitmap (plus separate per-block color attributes). I remember the display bitmaps scan lines were laid out in memory in a weird way - ...
8
votes
5answers
516 views
How to protect a ZX Spectrum mainboard from “ageing”?
I have some ZX Spectrums, and in some of them I observe a kind of "disintegration" process of the main board. The connectors break away etc. During the tests one of the boards burned out :(.
How can ...
6
votes
2answers
457 views
Membrane keyboard robustness
Some early computers used a membrane keyboard (ZX80, ZX81, Atari 400), or semi-membrane with minimal keys (ZX Spectrum). This is because it was cheaper than a mechanical keyboard. Intuitively I would ...
7
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 ...
9
votes
2answers
3k views
Who designed the Sinclair ZX Microdrive and why?
The ZX Microdrive.
It is well known that the Microdrive was introduced for the ZX Spectrum along with ZX Interface 1.
However, who came up with the idea and the design? Was it Sinclair themselves, ...
3
votes
1answer
1k views
Where to buy an 8 bit computer remake? [closed]
I want to buy a remake of an 8-bit computer, e.g. the ZX-Spectrum or c64.
Must haves:
Modern monitor output(e.g. HDMI)
Modern keyboard, no gum keys
Modern storage, e.g. SD card or USB stick, etc...
...
5
votes
1answer
388 views
What was the AMI SAGA and why wasn't it used it all ZX Spectrums?
This page has a note about a chip called AMI SAGA. Apparently it does the same job as the Ferranti ULA, but saves a little circuitry and runs cooler.
What was this chip? Some kind of uncommitted ...
1
vote
1answer
281 views
ZX Spectrum fault
I was recapping my zx spectrum when after just replacing one specific capacitor it stopped working as before.
The picture has multiple horizontal lines over the entire display.
This is especially ...
17
votes
2answers
551 views
How to create a switchless multi-system 2 button Atari joystick?
All systems that use the Atari 9 pin joystick standard make use of the following pins in consistent ways, with each direction and the fire button being connected to the ground pin when pushed.
1 - up
...
6
votes
1answer
351 views
Timex Sinclair 1500 and screen “jail bars”
I have tried to eliminate "jail bars" on the screen after UHF mod to video out (based on that: http://zx81stuff.org.uk/zx81/ts1500_video.html) by adding 460uf 16V capacitor between +5V and GND but it ...
12
votes
3answers
3k views
Native C compiler for Sinclair ZX Spectrum
I am looking for a native C compiler for the Spectrum 128. I would like one which:
Has good support for the latest C standard at the time.
Is not limited to compiling ridiculously short source code.
...
31
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 ...
19
votes
2answers
2k views
Why does this BASIC program declare variables for the numbers 0 to 4?
On pages 150 to 154 of William Tang's (1982) Spectrum Machine Language for the Absolute Beginner, there are these lines of code. (Note GOTO 9000 is the first non-REM statement in the program).
9000 ...
8
votes
2answers
633 views
ZX BASIC REM statement overhead
Since my other question has been answered and has given me a way to do high-precision timing, I've been experimenting with it a bit. The first thing I did was write a simple benchmark using the FRAMES ...
10
votes
4answers
2k views
Make a BASIC TAP file readable on Linux
I am trying to convert my own BASIC TAP files (containing BASIC programs) to text so that they are readable on my Debian GNU/Linux machine.
If I open them as is, I get this, which gives me some hope, ...
17
votes
5answers
2k views
Uptime in ZX BASIC
How can I obtain the uptime of a Sinclair ZX Spectrum machine (ZX48, ZX128, or Pentagon clone) via their BASIC interpreter? Specifically, the same value used by RANDOMIZE 0 to seed its PRNG. I would ...
17
votes
4answers
2k views
Understanding INKEY$ in ZX BASIC
The ZX BASIC Manual gives the following little program to demonstrate how INKEY$ works:
10 IF INKEY$ <> "" THEN GO TO 10
20 IF INKEY$ = "" THEN GO TO 20
30 PRINT INKEY$;
40 GO TO 10
While I ...
22
votes
6answers
3k views
ZX Spectrum tokenisation
The BASIC used in the early ZX Spectrum (and also its ZX predecessors) had this weird thing where every single BASIC token was printed onto the keyboard, and for example PRINT or LOAD were entered by ...
16
votes
2answers
3k views
What is causing the problem with the RAM in this (claimed) Spectrum 48k?
I bought what was claimed by the seller to be an Issue 4S Spectrum 48k.
I tried loading games and some worked while others didn't. Turns out it was the 16k ones that worked and 48k didn't. This ...
5
votes
2answers
421 views
Timex 2048 RAM contention ULA/video output
I used to own a Timex TC-2048 ZX Spectrum 48K compatible clone.
I programmed it in assembly extensively, both for fun and when learning, and also when testing things for writing my own ZX Spectrum ...
5
votes
1answer
404 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 (...
6
votes
2answers
524 views
Spectrum clones 512x192 mode usable text resolution
The original ZX Spectrum has a resolution of 256x192, for 32x24 text. Some later clones add a 512x192 mode. The most obvious thing to do with that is try to display 64x24 text. According to https://en....
12
votes
4answers
922 views
What are tacts in the context of ZX Spectrum systems?
I've heard the term tacts when referring to some hardware capability, e.g. "tacts on one frame" or "tacts per second". I tried Googling this but surprisingly did not find anything relevant. What is ...
4
votes
4answers
653 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 ...
67
votes
8answers
18k 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 ...
20
votes
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 ...
7
votes
1answer
2k views
What is the maximum BAUD rate for ZX Spectrum tapes?
I've played with various BAUD rate programs that allow you to save most of the RAM into a cassette tape up to around 9600 BAUD. Has anyone written or have a way to write the ram to tape (not ...
