Video

Now that the original Z80 is discontinued, will the eZ80 or an actively made clone or FPGA still work with this PCB? I'm aware that 40-pin adaptors for the ez80 are available.

So sad that Zilog has discontinued the entire Z80 line up, and is now going through discontinuing eZ80 I believe.

What a fantastic video! I received my ZX Spectrum 48K for Christmas 83. I still have fond memories of sitting in my mum & dads kitchen with it hooked up to a 14 inch portable tv and then spending hours trying to get games to load! And Manic Miner!...so glad you choose that game to test your ZX. I too still play it today every now and then. Did you know on the original ZX if you turned the music off the game ran much faster due to lightning the load on the CPU!

Using the Xbox message sound is so distracting.

i loved my speccy 48k, it was that little machine that started me off in computers, programming in basic, here youve basically recreated to perfection what i had in 1983/4, well done, though was a bit worried in using the heat to shrink the wrapping around the tape, wouldnt that of also affected the actual tape?

Really enjoyed the video. I'm amazed that you can still get the Z80!

You done Sir Clive proud!

Thank you for the video. Power supply is not original. :) Is next step is 128 kB?

Unfortunately, i've failed to even solder 20 pins on the RPI0 for my ZX Spectrum NGO. Glad somepeople is making a modern Speccy for talentless duck like me. Love my NGO!

I lost my ZX Spectrum in a war. But I still remember the day I got it. What a magical moment. Thanks for helping me relive it!

This is beautiful, it is pleasure to watch. (Imagine you are ZX Spectrum fan and your love gives you this as a christmas gift :D including the "building a brand new ZX Spectrum"... 🎄💥🔥♥❤❤)

is this a harlequin or is this something else?

Wow, so impressed. Now I need to do this some day!!!

brilliant

TOOK ME 40 YEARS TO UNDERSTAND THE WORKINGS OF THE VIDEO OUTPUT OF THE ZX SPECTRUM +, since I was a child ZX Spectrum 16k, 48K or + The Video output by the ULA is Y, U & V signals using the following Video standard, PAL 625 Line Interlaced @ 50 Hz. !_____________________ PAL 625i @ 50Hz ____________________________________ [Resolution]: The display consists of 625 horizontal lines, and each frame is composed of two interlaced fields, resulting in a refresh rate of 50 Hz. [Frame Rate]: Operates at a field rate of 50 Hz, meaning that it displays 50 fields (25 frames) per second. Each frame consists of two INTERLACED fields. [Horizontal Scan Frequency]: 15.625 KHz, this means that the electron beam scans across the screen horizontally 15,625 times per second. [Color Encoding]: Uses a phase alternation technique to encode color information. This helps in minimizing color errors that may occur during transmission. The color subcarrier frequency in PAL is 4.43 MHz. [Aspect Ratio]: The standard aspect ratio for PAL 625 is 4:3, meaning that the width of the display is 4 units for every 3 units of height. NOTE only the horizontal lines are defined and not the vertical lines, they are instead have a duration of 64 microsseconds in time. !__________________________________________________________________________ -> The 50Hz interrupt was synchronised with the VBI (Vertical Blanikg Interval) of the video signal. -> VBI is the brief period when the electron beam in a CRT display moves from the bottom to the top of the screen. -> Each Frame consisted of 312.5 (312.5 x 2 = 625i) scan lines interlaced, one frame does the ODD scan lines and the other does the EVEN scan lines. -> Each scan line takes exactly 224 T states or processor cyces. {(CPU clock)/(Horizontal Scan Frequency)} or 3,500,000/15,625 = 224 -> After an interrupt occurs, 64 scan line times (14336 T states) pass before the first byte of the screen is displayed, including VBI. -> Each frame comprises 64 scan lines + 192 scan lines of framebuffer or bitmap + 56 scan lines of lower border of screen. -> Only the last 48 of the 64 scan lines of the above border are visible. -> The side border is 48 pixels wide at each side. -> A video screen line starts with 256 screen pixels, then right border, then horizontal retrace, and then left border again. -> A video screen line is therefore timed as follows: 128 T states of screen (framebuffer), 24 T states of right border, 48 T states of horizontal retrace and 24 T states of left border. -> The image size of the framebuffer is [256×192 = 49,152] pixels. -> Character resolution of 32 columns by 24 rows: 32 × 24 -> One character cell is composed of 8x8 pixels -> In practice, this means any character cell can only use two selected colours for colouring the contained 64 pixels. -> The Discrete Graphics RAM requiring 6,912 bytes (6.75 KB) is directly accessible to the CPU at addresses 16,384 to 23,295 (after the ROM). -> An ULA which reads the lowest 6,912 bytes of RAM to display the screen. -> The original ZX Spectrum computer produces a one bit per pixel, requiring 6,144 bytes, known as Pixel BitMap. -> Colour is stored separate from the pixel bitmap, as a 32×24 cell grid, requiring 768 bytes nown as Colour Attribute Data. -> Using one byte for each of the characters or character cell. -> The main pixel bitmap is stored at the very beginning of the graphics RAM, while the attributes array follows immediately behind it. -> 6144 bytes worth of bitmap data, starting at memory address &4000 or 16,384 -> 768 bytes colour attribute data, immediately after the bitmap data at address &5800 or 22,528 -> 6,144 bytes + 768 bytes = 6,912 bytes of Graphics Memory. Colour attribute data -> The colour attribute data overlays the monochrome bitmap data and is arranged in a linear fashion from left to right, top to bottom. -> Each attribute byte colours an 8×8 character on the screen and is encoded as follows: 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | ------------------------------------------------------------------------------------------------------------------------| F | B | P2 | P1 | P0 | I2 | I1 | I0 | Where: F sets the attribute FLASH mode B sets the attribute BRIGHTNESS mode P2 to P0 is the PAPER colour I2 to I0 is the INK colour So for each 8×8 character position you can only set two colours; this limitation is the sole cause of what is affectionately known as “attribute clash”. -> url worldofspectrum.org/faq/reference/48kreference.htm -> url www.breakintoprogram.co.uk/hardware/computers/zx-spectrum/screen-memory-layout This memory is used to store the pixel data for the 256x192 pixel display, where each pixel could be one of the 15 available colors. The rest of the RAM was used for system variables, BASIC program storage, and other functions. !___________________________________________________________________________________________________________ ZX Spectrum 16K, 48K, and ZX Spectrum+ 128K, +2, +2A, +3 CPU cycles per PAL line 224 228 PAL line time 64 μs 64.28 μs PAL lines per frame 312 311 Frame time 19.968 ms 19.9915 ms Frame rate 50.08 frames per second 50.02 frames per second Display Vertical Synchronization by the Z80 maskable interrupt line >---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Very many modern programs use the fact that the screen is "written" (or "fired") to the CRT in a finite time to do as much time-consuming screen calculations as possible without causing character flickering: although the ULA has started displaying the screen for this frame already, the electron beam will for a moment not "pass" this or that part of the screen so it's safe to change something there. So the exact time in the 1/50 second time-slice at which the screen is updated is very important. Each line takes exactly 224 T states. The 48K ZX Spectrum memory map is shown below, #xxxx denotes a hexadecimal number, lengths are decimal Start End Length Description #FF58 #FFFF 168 Reserved #5CCB #FF57 41,612 Free memory #5CC0 #5CCA 11 Reserved #5C00 #5CBF 192 System variables #5B00 #5BFF 256 Printer buffer #5800 #5AFF 768 Attributes #4000 #57FF 6,144 Pixel data #0000 #3FFF 16,384 Basic ROM ->url www.overtakenbyevents.com/lets-talk-about-the-zx-specrum-screen-layout/ !_________________________________________________________________________________ The timing is expressed as a T-states of the CPU and, when recalculated to pixels, the top of the border is 64 lines, with 48 lines being visible as the actual border. The bottom side of the border has 56 lines, with some being outside of the visible area. On the left and the right sides there are 48 pixels, some of them are outside of the visible area. !_________________________________________________________________________________ The device uses 14 MHz crystal as the master clock, and it gets divided by 2 to get 7 MHz pixel clock. The active raster is 256 pixels, and if we assume that standard 15.625 kHz horizontal scan rate is used, it adds up to 448 total pixel clocks per line. Due to standard horizontal timing, there will be 364 pixels of video at most, leaving up to 108 pixels for border area. And due to standard video timing, there should be 312.5 lines per video field, or 625 per frame, of which up to 576 contain video. But we can safely assume it outputs progressive video at 312 total lines per frame with 288 active video. Not all are visible due to overscan. This leaves 96 lines for border area in total. Using this as a reference, I found a ZX Spectrum reverse-engineering website which confirms this, and actually has the values. Borders are 48 pixels on left and 48 pixels on right for a total of 96 pixels. Due to overscan, not all of them are visible on a screen. This leaves 96 pixels for horizontal blanking and synchronization area. -> The vertical border is said to be 48 lines before active raster and 56 lines after active raster. !_________________________________________________________________________________________________ -> The ULA is reading the screen memory, about 60% of the 1/50th second time slice in which a frame is generated. -> The other 40% the ULA is building the border or generating a vertical retrace. -> This behaviour is actually used in some programs, for instance, in Arkanoid. *************************************************************************************************************** TOOK ME 40 YEARS TO UNDERSTAND THE WORKINGS OF THE VIDEO OUTPUT OF THE ZX SPECTRUM +, since I was a child

This is a great step by step instruction guide. I sure wish all board projects came with a video from Retro Teatime.

Thought I was building my ZX80 all over again, great video

I feel nostalgic for something I wasn't around for...

yellow purple black is 47 ohm

It's amazing the lengths us Speccy fans will go to to recreate that fateful birthday or Christmas! Few outside the hobby would understand!

Thank you so much for this, mate! Just subscribed. I'm falling back into love with this machine after 30-odd years. Cheers!

The only year ZX Spectrum was not produced was 2003. Before and after it was and still is. Unless you are Brit-centric.

I'm waiting for my Spectrum Next Edition 2 to arrive. But watching this video, I am totally in awe.

Basic programming manual was originally wire bound.

I just love the attention to detail!.......Make your next board an issue 5 yellow to annoy everyone :-P

A few years ago, when looking in my parents' attic, I found my old Spectrum from 1983, I cleaned it and of course replaced the keyboard membrane, and connect it to a TV, no signal but the keys "clicked". I removed the RF modulator and connected to a composite port et voila, it still works as new. I also found a lot of old tapes and a lot are still working, what a great little machine.

Nearly 40 years on and I have still not read the spectrum manual.

The click bait said "the first new ZX spectrum in 30 years" which is a false claimer, because re-building ZX spectrum from scratch using off the sell parts is routine in the ZX scene.

I am SHOCKED that you put the transformer in the box without tying its cable! So unprofessional. 😂😂😂😂 Joking aside, impressive work.

NTE846 appears to have the same pinout and specification

I always wondered why ctystals are installed at a slight angle (even in mass produced computers). Is there a reason for it?

LOAD dit dit

This is amazing! my friend had the 48k and i had the 128k +2 great days playing these machines.

Which way around is TR6? The diagram doesn't say flat face east yet the transistor page on the website does. It's difficult to see which way around it is in the video but it looks like the flat side faces west. Thanks

Subbed. 👍

1st one we had was the rubber keyd one, after a couple of years heavy use the metal cover peeled of from the heat lol. Next one I had was the 128k+ vast improvement over the original, longer loading times for better sound and games, also had the integrated tape player.

Amazing work! I still have my original ZX Spectrum but maybe I build him a companion one day!

Great job, great video! thank you for this, it is a legendary machine and the legend goes on over the years! cheers!

In the early 90's I saw Spectrum keyboards stiched together and sold as bath-matts. 😆

Sir Cilve says "Ohhh" ;) Do you produce them to sale for sons can buy this for dads ?

you need some nailclippers

You got it wrong on the resistor value, bad boy, go back in the back of class. Resistor colour code Yellow Purple Black Gold is 47 ohms 5% tol. NOT 470

Noob

Love the choice of music 😊

Square and white, GX4000 or ZX80? ZX80 from those screw hole placings, my final guess.

It is is a pleasure for my eyes to see yellow resistors, not those crappy blue ones with hair like legs.