65
votes
Accepted
Can a USR command damage a ZX Spectrum?
I am the author of that video. I wrote a little article about that years ago. I will copy that for you here:
Original article here:
http://www.zxprojects.com/index.php/the-fix-a-spectrum-blog/29-the-...
- 18.6k
23
votes
Accepted
Which ports are which on this Soviet ZX Spectrum clone?
No need for any special Spectrum knowledge. It's about power, and there is no rectifying, no appropriate sized capacitor and voltage control elements on this board, so it most definitely does not take ...
- 208k
14
votes
Accepted
How compatible is the Leningrad clone with the "original" ZX Spectrum?
Leningrad is a primitive and not particularly compatible clone. However, it is pragmatic, so the incompatibilities are not always going to show up. The main differences are due to a completely ...
- 4,072
13
votes
Which ports are which on this Soviet ZX Spectrum clone?
Looking at the linked schematic and the photo of the internals, I'd say the ports are the following (listed from the reset switch over)
Reset
Power
Composite video (or possibly monochrome luma only)
...
- 4,517
13
votes
Accepted
Spectrum clones 512x192 mode usable text resolution
I had two micros when I was growing up: the SAM Coupé and the Acorn Electron.
The SAM Coupé has a 512x192 mode much like you discuss. The SAM's display is physically wider than a Spectrum's though, ...
- 35.6k
13
votes
Accepted
Did any ZX Spectrum clones use the Z80's interrupt mode zero?
IM 0 is the backwards-compatibility mode with the i8080 CPU. You have to use some external circuit to provide desired RST 0..38h instruction. RST 0 is effectively the same as RESET, RST 38h is the ...
- 5,427
11
votes
How compatible is the Leningrad clone with the "original" ZX Spectrum?
In the USSR, the analog TV sets used SECAM, not PAL, so I imagine that the timings will be different between the UK Spectrums and the Leningrad.
SECAM is, like PAL just the colour encoding and on top ...
- 208k
11
votes
Which ports are which on this Soviet ZX Spectrum clone?
Only you can decide which port is which as you are the only one with access to your HW. I would use multi-meter and or short circuit tester:
Power supply
I see no stabilisator nor DC/DC nor AC/DC ...
- 7,152
10
votes
Can a Harlequin ZX Spectrum clone be modifed to run CP/M?
well even old ZX 48K and clones have exposed the AD/DB/CB buses along with /ROMCS signal which can actively disable inbuild ROM. So you can make a small HW that has 16 KByte of SRAM that replaces the ...
- 7,152
10
votes
What computer is this, a clone of a ZX Spectrum?
Judging from the block graphics on the number keys, this computer is a ZX Spectrum clone. On the 8 key, it's a solid graphic, and on the 7 key it's filled in in the lower left corner. This is ...
- 38k
9
votes
Accepted
How does DRAM refresh work in the Leningrad?
There's just one thing though: the Z80 doesn't flip the highest bit of the R register,
True
and so R only iterates across 32k.
Not really, it doesn't access 32 Ki but 128 rows.
So how does the ...
- 208k
9
votes
Which ports are which on this Soviet ZX Spectrum clone?
Computer "Composit" (Leningrad+).
http://sblive.narod.ru/ZX-Spectrum/Composite/Composite.htm
http://sblive.narod.ru/ZX-Spectrum/Composite/CompositeSCH-MONT.gif
Left to right:
KEMPSTON
Right
Left
...
- 361
8
votes
Can a Harlequin ZX Spectrum clone be modifed to run CP/M?
The hardware modifications are possible, and actually already done. The "SuperFoo Harlequin 128" is an all-RAM design based on the original Harlequin that should be capable of running CP/M (Just like ...
- 32.4k
8
votes
Accepted
Fire button of Timex TC/TS 2068 Joystick
Androids Timex cartridge game disassembled machine code using bit 7, for checking the Timex joystick 1 0x1F6 port for the fire button:
ld a,00eh
out (0f5h),a
ld a,001h
in a,(0f6h)
...
- 2,581
7
votes
How does DRAM refresh work in the Leningrad?
From the schematics, I can see this uses a single RAM bank, opposed to the original Sinclair machine, which uses two separate RAM banks.
That means that the entire RAM address space must be shared ...
- 18.6k
7
votes
Fire button of Timex TC/TS 2068 Joystick
You are reading it right. The schematics do not match the description.
- 27k
7
votes
Fire button of Timex TC/TS 2068 Joystick
According to the Timex/Sinclair 2068 Third Party Software Guide, it’s D7. 0 indicates the button has been pushed.
Also, here's the Timex tech manual (from Timex).
6
votes
Accepted
What file formats were used for binary executable files on later Sinclair ZX Spectrums?
The original Spectrum +3 manual has a comprehensive description of the disk format:
http://www.worldofspectrum.org/ZXSpectrum128+3Manual/chapter8pt27.html
For TR-DOS, it's worth knowing that the ....
- 1,311
6
votes
Did any ZX Spectrum clones use a 16 bit datapath between memory and video generation?
There is a Spectrum clone, namely ATMTurbo, that uses 16-bit memory bus. However, 16-bitness of memory is only used in extended video modes of the machine, including text mode, 320x200 16bpp mode and ...
- 9,850
6
votes
Accepted
How exactly does Leningrad contend the memory?
The ideas behind:
DRAM access takes place at every CPU cycle.
Every other DRAM access (or slot) is for video (further differing between attribute and pixel reads), the rest slots are for CPU. In fact,...
- 9,850
6
votes
Did the Samsung SPC-650 have any hardware or firmware differences to the genuine Sinclair Spectrum+?
Very little seems to be known about the SPC-650. Apparently it didn't sell well, and ZX Spectrum compatibles were on the whole pretty much overlooked in the far east, excepting Russia.
There's a blog ...
- 38k
5
votes
How did the Spectrum clones with TR-DOS and paged memory load and run code files from disk?
How it [likely] works
When ZX-Spectrum with Beta interface (re)starts, Beta Disk Interface sets ROM_CS flag to disable its builtin ROM and connects TR-DOS ROM to initialize the interface, dirves, and ...
- 51
5
votes
What are the differences between Leningrad-1 and Leningrad-2?
The second paragraph of this article lists the differences of Leningrad-2 from the original Leningrad:
Из конструктивных отличий от Ленинград следует отметить, что
изменилась схема сброса кадровых ...
- 193
5
votes
Accepted
Where can this "boot.B" file be coming from on this Spectrum TR-DOS disk image?
I think possibly your emulator is fooling you. Per this FUSE feature request, leading to this patch in particular and this commit, FUSE synthesises a boot.b and adds it to the disk directory if you ...
- 35.6k
5
votes
Accepted
How do I use the extra commands in the Spanish version of the 128k Spectrum ROM?
It turns out that the commands are in Spanish despite the only mentions of them I had found only listing them in English:
EDIT → EDITAR
DELETE → BORRAR
WIDTH → ANCHO
RENUM → NUMERO
They are not ...
- 6,323
4
votes
Did any ZX Spectrum clones use a 16 bit datapath between memory and video generation?
I've just discovered a couple of East German clones doing what I describe and having a 16-bit datapath between memory and video generation. This answer is about the ZX Spectrum clone developed at the ...
- 38k
4
votes
Accepted
Are the last 4 bytes in .SCL disk image files for Spectrum clones meaningful or spurious?
Look carefully at the docs again (Web Archive one).
"The file bodies are stored after the directory entries.
Basic program and data array files have an addition at the end of the file."
If it is ...
- 257
4
votes
Details of ZS Scorpion port 0x1ffd
Working backwards from FUSE — machine_current->ram.last_byte appears to be the current state of 7ffd and machine_current->ram.last_byte2 is 1ffd:
1ffd:d1 is active high;
1ffd:d0 appears to ...
- 35.6k
3
votes
Can a USR command damage a ZX Spectrum?
It appears that this rumour is in fact false. A video of the commands being run on a real Spanish ZX Spectrum shows that the only visible effect is garbage output.
- 18.2k
3
votes
Accepted
Can a Harlequin ZX Spectrum clone be modifed to run CP/M?
The latest version of the "Superfo Harlequin 128 (issue 4)" supports ALLRAM mode
https://onedrive.live.com/?id=E0ADBB58ADB8D869%21209864&cid=E0ADBB58ADB8D869
You can connect a floppy ...
- 46
Only top scored, non community-wiki answers of a minimum length are eligible