75

well, if you really want those games back, just buy the tape. Then buy a cassette player (they're cheap, you can try to get a high quality one) or find a friend who still has one. Now: Make sure to clean up the player heads with isopropyl alcohool before using it. Rewind the tape Extract it and use 2 pencils on the reels to gently tighten the tape so it's ...


65

Both the Sinclair ZX Spectrum and the Pac-Man arcade machine used the Zilog Z 80 CPU. Pac-Man's display was slightly larger and vertical at 224×288 while the Speccy's was horizontal at 256×192. The Speccy did not have hardware sprites or pixel-addressable colours. The original 48K Speccy only had "1 bit" beeper sound though later models had an AY ...


49

First, many thanks for the great question. This may well be my favourite retrocomputing video of them all, so I contemplated having a look at the executable for a while myself. So, this is what I did: To download the audio, I went to the same YouTube video and used 4K Video Downloader (mainly because it clearly shows which audio is the original one, so that ...


32

Back in the '80s, I wrote a couple of games too. A few years ago I have found the old cassettes with those games, but I had no tape deck at all. I bought a "USB walkman" Basetech BT-USB-TAPE-100 on eBay for a few dollars. Then I just plugged this deck to my PC and record my old tapes to uncompressed WAV (at full possible sample speed, 48 kHz, 16 ...


17

This is relatively normal for the original PSU. The supply unit is a "soft" one that will output a much lower voltage under load when connected to the ZX Spectrum. 12 or even more Volts are normal.


16

In regards to "is there a way to play my old games again?", there is a good chance that they are available online somewhere. You might start with the Internet Archive. Collectors and enthusiasts have already made archive copies of almost all spectrum software so if your games were ever on sale there is an excellent chance that someone has already ...


16

Did you check the archive at www.worldofspectrum.org? They preserve whatever spectrum software they can get their hands on, not just games. If you don't find it there, it is likely someone in the forums will assist you to transfer it to .tzx / .tap format and they will upload it to the site. Btw, I've bought many used tapes and was able to load them on a ...


16

As far as I did my own experiments with the ZX Spectrum keyboard, I strongly disagree with that quoted text. The ZX Spectrum keyboard did ghosting, of course. Let's look at the key matrix: Imagine you press A, S, and Z keys together. It results in a "ghosted" Caps Shift. When the CPU starts to check the CS-Z-X-C-V row, it drives the A8 line to &...


13

POKE 16418,0 is for the ZX81, not the Spectrum - the equivalent system variable on the Spectrum is at 23659. You need to take care when poking this address, as it's liable to cause a crash if the program exits (or displays a scroll? prompt) while the lower screen is disabled, but the following program demonstrates the principle: 10 POKE 23659,0 20 PRINT AT ...


11

The .z80 format comes from the Z80 emulator by Gerton Lunter. He released some documentation about the file formats used in it, and regarding offsets 11 and 12, this is what the manual says: .Z80 FILES: ----------- The old .Z80 snapshot format (for version 1.45 and below) looks like this: Offset Length Description 0 1 A register ...


11

About the R register on a real Z80: But is the 8th bit actually used? Yes, it's freely available and won't be touched by any instruction except loading R Is its behaviour undocumented or can it only be altered by loading it with a value from the accumulator It's well documented and can be used like assumed. When loaded all 8 bits from A are stored in R - ...


11

Assuming you use the SDCC backend: SDCCs printf does not include float support by default. You need to recompile the z80.lib library with USE_FLOATS=1 set in printf_large.c


11

In order for the program to load in one go without having to open a new file for each section, you'll need to combine them into a single .tap file. Happily, the .tap format is designed to make this easy - concatenating two files together results in a valid file. So, after creating part1.tap and part2.tap with zmakebas as above, you can combine them with: cat ...


10

Whilst Timex assembled Sinclair ZX Spectrum computers, the Timex architecture of the TS/TC 2068 is a reengineering of the ZX Sinclair behaviour with improved and more reliable technology. In the particular case of the Timex 2068, it has 128K of RAM, 2 ROMs, an extended BASIC, a new paging scheme, new video modes, and a sound chipset. The downside is some ...


10

The second shift register is wired to provide a 4-cycle delay after the pixel data is loaded before it is displayed. This is presumably designed to allow the system enough time to load the corresponding attribute data into the pair of storage multiplexers labelled D30 and D31 after the pixels are fetched but before they start displaying; if it were missing, ...


9

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 Leningrad refresh the entire DRAM? Well, like any other machine using 4164 RAMs - by refreshing all 128 rows. It is important to separate address ...


9

Yes, quite possibly. Unless the tape is damaged with complete dropouts, I would be cautiously optimistic that you can recover it. While ageing tends to increase wow/flutter, and can cause the recording to "fade" for lack of a better word, complete drop-out is uncommon unless the tape is actually disintegrating, or the oxide is flaking off. There ...


8

For games with very distinct playstyles per level, such as Ghostbusters II https://m.youtube.com/watch?v=4wnPZEM1IvQ (sewer drop, side scroller) and the 128k version of Short Circuit (exploration mode, side scroller mode), the segments of the game were closer to different games entirely than a common engine into which things could be loaded. (This is ...


8

Interrupt Mode 2 is not a ZX Spectrum feature, it's a feature of the Zilog Z80 CPU itself. Per Raffzahn@'s comment, the answer to your question kinda depends on what kind of threading you're talking about. There are generally two levels of abstraction when it comes to multithreading, and two meanings of the term. First is the hardware level Simultaneous ...


8

It doesn't make any difference. The border colour changes between red and cyan whenever the tape loading routine detects a change in level between low and high, and this happens many times over the period that a video frame is being sent to the display (from top to bottom), producing the stripes. Static stripes would just mean that the level changes are ...


8

##TL;DR: Not really sure where this claim of over 5 M computers, including 1 M Spectrum comes from. While still not correct, it would sound more believable the other way around, as 5 M units, including 4 M of Spectrums. So my guess is, that it's for one a very rough number, but more important the author simply used the wrong label for the additior. Deails: ...


8

This is a wiki answer, so please amend with additional solutions, or improve the ones below: CPC Tape Software Tape images are normally downloaded as a .cdt file, the same file format as the Spectrum .tzx tape format. Though these do not contain any sound data, they can be played back on an Android or iOS phone, using an app such as 'PlayZX' or 'Speccy Tape'....


7

Not simultaneously, as it only has one CPU, but it has a 50 Hz timer interrupt, so it can do time sharing processing, provided that programs are well behaved, as there is no memory protection and no supervisor mode in the CPU. As a proof of concept, I've written a small task scheduler and tasks that are executed in a time sharing fashion (with a 20ms ...


7

All of the popular, early 8-bit CPU's support hardware and software interrupts. Therefore, they can all theoretically support preemptive multitasking, which I think is what this question is really asking. The relevant article from Wikipedia states: In simple terms: Preemptive multitasking involves the use of an interrupt mechanism which suspends the ...


7

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 between the video circuit and the CPU, while the original Sinclair machine only shared 16KB of RAM. Now, it happens that DRAMs are not only refreshed using RAS ...


7

The correct answer to your question is YES, and NO. YES, if you are editing a long line in the editor of 128K BASIC, you are limited to the size of line buffer, which can hold only 20 screen rows. You can confirm this by reading the ZX ROM Disassembly which can be found here (note that you will need to be reading disassembly for ROM 0). Let me quote a ...


7

Yes. Speed must be 150ns or faster, technology should be NMOS (CMOS produces too sharp edges that may cause ringing, due to non equalized traces in the PCB, so they may or may not work) and must support 7 bit (128 rows) refresh mode. Not that I know. Which are the "standard factory modifications"? The only one I know of is that weird capacitor connected to ...


7

Commodore owned MOS technologies, who made the VIA chips. Although the VIC-20 might have been able to replace a VIA chip with a 4051, a 74LS139, a couple of 74LS373s, and eight resistors, I don't know that doing so would have really saved anything compared to the in-house cost of the VIA. Further, using a second VIA made it possible for them to have one ...


6

The 128K mode retains the "old" cursor key combinations - in particular, CAPS Shift 6 stands for cursor down, CAPS Shift 7 for cursor up.


6

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 .TRD file format is a simple sector-by-sector dump of the disk contents with no additional headers, so any description of the .TRD format (such as this one on zx-...


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