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Thanks a lot! Actually, you can already start thanks to the emulator! 😄

Age is a secret🤣

Thanks for your comment! I am not sure to understand what you mean, do you mean that the user should be able to input KB or MB, but by default the input is interpreted as bytes?

@@Zeal8bit Hello! I meant simplifying the user experience. So if you flash firmware, you can add default value of ROM address and give possibility to change it to user or just press "enter". This way the user won't have to remember and enter the same values ​​every time.

@@tov_marshal Oh I see, thanks for the clarification! It is a good point, adding a header in the bootloader binary would help a lot, the user would only have to transmit it and everything else is automatic (destination, size, etc..)

@@Zeal8bit That's certainly one way to do it. But I think they were saying that your program on the machine that handles flashing could take input from the user on what it should do with the received file. Doing so would in principle allow the user to request that any binary data be flashed to the rom, starting at an arbitrary address. ----- I do think that the header approach is a good one, though. Instead of expecting the user to specify details, it would mean that you can't accidentally flash the binary data to the wrong part of the rom without modifying the generated binary first.

@@jnharton That's currently the case already, when flashing a binary to the ROM, the user can specify the destination address in ROM directly from the bootloader, hence my misunderstanding😄

Zilog are only ending production of the 40-pin DIP version. The PLCC version used by the Zeal (as well as the eZ80) are still being made.

There are plenty of Z80 CPUs available on the market, in DIP and PLCC, for us hobbyists. In the worst case, there is still the Z180, which is in production and also available in PLCC, and in the case where it also get discontinued, there are FPGAs for a real 1-to-1 emulation

I considered it, the main issue I have is the licensing of HDMI. HDMI is NOT royalty-free, in theory, you have to pay to integrate it in a product. In practice, some say it is possible to have the connector but not use the HDMI protocol, and use the DVI protocol (TMDS) instead. I haven't found any official statement that allows this. Anyway, another possibility would have been to use DVI connector, but I have seldom seen DVI screens myself, it is easier to find a VGA screen. The remaining possibilities are using DisplayPort or even better USB Type-C, which supports TMDS too! In all cases, if I end up implementing digital output, it would be done through the extension/module port present on the video board (below the 3.5mm jack connector)

@@Zeal8bit I've seen plenty of products using the HDMI connector, but simply not advertising it as HDMI. In one instance, it was labeled "IMDH"! It's all about the trademark but really, the point is moot as DVI and DisplayPort are perfectly fine alternatives. Simple [X]-to-HDMI and [X]-to-VGA-adapters for both are readily available for pennies.

@@ser_olmy They're also needlessly complicated for a Z80 based computer, especially if the actual resolution is fairly low. And there is nothing simple about such an adapter, because unless the video card can secretly do VGA ("magic" adapter required that signals it should output VGA) the adapter actually has to convert hdmi output (digital, 4x differential signaling pairs) to vga output (analog rgbhv).

@@jnharton There's a reason why people in the retro community spend significant amounts of money on HDMI mods for old 8-bit systems (Atari, Commodore, Acorn, MSX etc). Besides VGA inputs being rubbish on modern monitors (if they have them at all), there's also interference, jail bars, non-trivial lag, and inaccurate colours. If this wasn't the case, there would be no market for the insanely expensive RetroTink. DisplayPort/HDMI-to-VGA adapters can be had for way less than $10 on AliExpress. I have a bunch of them, and they work just fine on everything from modern PCs to the C64 Mini.

​@@jnharton If there were no major issues with hooking an analog video source up to a modern LCD screen, there would be no market for the very expensive RetroTink. The various Digital-to-VGA adapters are less than $10 on AliExpress, and they work fine with anything from a modern GPU to the C64 Mini. I can attest to that, as I have a bunch of them.

From a hardware point of view, the Agon Lite 2 uses an ESP32 for the graphics, which is a dual-core 32-bit MCU @ 240MHz (much more powerful that the eZ80 itself). If I recall correct, the Z80 doesn't have control over the video RAM, it can only give commands to the ESP32 which itself will interpret the request and update the video RAM. You can see the ESP32 as a coprocessor in that case. This is not how video chips worked on the retro 8-bit computers (or retro consoles) The retrocomputers and retroconsoles (NES, Gameboy, GameGear, SNES, etc...) manipulate the VRAM directly from the CPU in order to generate an image on screen. For example, you provide a 16x16px tile by copying each pixel color to a certain part of the video memory. Then you write to another part of the VRAM to specify where you want this tile to be shown. In other words, you manipulate all the bits of the VRAM via the CPU (or DMA on more advanced computers) which themselves will be interpreted in a certain way by the video chip. This is exactly how the Zeal 8-bit Video Board works too. You have 128KB of video memory space that the CPU needs to manipulate in order to show something on screen. Not only you have full control of the video output, but the communication is done via the parallel bus, and not a serial protocol, so a single `out` or `ld` instruction on the Z80 is enough to show a character or control the cursor for example.

@@Zeal8bit The NES and SNES game systems don't actually have direct access to the video ram (aka VRAM), as I understand. Instead they utilize a special video hardware unit Nintendo calls (called) a PPU. And the PPU (Picture Processing Unit) doesn't actually have much VRAM at all, because the graphics data comes directly from the cartridge's "Character ROM" (organized as 8x8 tiles") when they are needed. Instead the very small amount of VRAM is used to store information regarding what tile should be drawn to which part of the screen (tile map?). So the PPU is basically drawing each frame by reading the needed data from ROM on the fly. ----- You could see it as a crude solution or as a very clever solution that minimizes the hardware needed to get the desired results. For a much better (and very thorough) explanation, you can check out this website: www.copetti.org/writings/consoles/nes/

@@Zeal8bit Does your graphics card also implement some of tile engine/tile-based rendering? Or is that just easier to describe it's video menory in terms of tiles, rather than just as some sort of large framebuffer?

@@jnharton The Zeal 8-bit Video Board is only tile-based at the moment, so yes, we can say that it implements a tile engine (you can compare it to the Gameboy PPU) There is no framebuffer, in fact, it would take a lot of video RAM (300KB) and would be too big for the Z80 to handle at decent speed

Thanks a lot!

Oh yes, I still have plenty ideas about new software, improvement for the OS, the video board firmware and even new hardware modules. Regarding CP/M, it can run on the board, I did a demo in one of my older video but didn't go beyond because it was quite limited for my usage, I preferred to concentrate on Zeal 8-bit OS

It's great to see you here! I didn't take time to check the different file transfer protocols over UART, I will definitely check, it's annoying to provide the size and UART data corruption is still possible in theory, mainly when the signals are software generated. I also added a CRC module in the video board, which can be very convenient to check the integrity of any stream of data

I also love the idea to put all in the 3D case, which is very nicely design and well printed in PLA material, totally homebrew, and it can turn on/off the board with a touch sensor, giving a modern touch to this retro computer. Astonishing 🤩

Thanks for your comment! Feel free the join the Discord if you need some help to get started When I started the project, I also wanted an all-in-one keyboard, but that would require more time, I don't want to postpone the release of the project anymore😄

Thanks!

Haha, thanks! You were fast!

haha no, it's more about the time invested in the project 😉

It is planned, I would like to write a technical manual about it to explain all the features and design choice. In the meanwhile I wrote a quick guide here: zeal8bit.com/getting-started-zvb/

Even if a lot of people like to criticize the ZX80 and ZX81 because the standards they have today, I am convinced these two computers meant a lot to many people, they made computer science available for anyone. It's never too late to start new projects 😉 Maybe you can have a try implementing a cooperative multitasking OS

If I recall correctly, he wrote it in 6502 assembly, right?

@@Zeal8bit yes, very true. He wrote it in 6502 assembly. You don’t speak that, huh?! I asked Claude AI to document the steps needed to port and it’s intense. Then it added steps for augmenting a developer’s knowledge via AI scratchpadding as well as commenting the asm. So maybe there is hope? 😭

@@Zeal8bit OH random thought… could get FUSIX working with windowing + a 6502 emulator to play that game xD. The FUSIX team has a very lightweight emulator indeed.

I like the Z280 a lot, but it's much harder to find in +20 quantity than the classic Z80

You mean something like this: github.com/Zeal8bit/Zepto ? 😉

@@Zeal8bit geez! Yes! Beautiful! Ok next challenge! A gui and a clone of Abiword and of Kate 🤣 😜

That's doable, or even simpler: an FTP client. In both cases, I need to make a Wifi extension board for it 😄

😂 Well Z80 CPUs are also still proprietary unfortunately

Yes I also think so, it's a shame they didn't do this. I mean they did implement all of that, the code is here, all they needed is an assembler and the documentation...

Thanks for your comment! Which kind of details would you like to know? I made some videos that are tracking the FPGA board but they were not centered around the PCB itself

Thanks a lot!

Thank you! 😄

The kits are back in stock already😉

Hello! That looks like a very interesting project. I personally still have quite a lot of things to do on Zeal project. But I would be happy to hear more about it, you can join the Discord, some members can also help

@@Zeal8bit Tks for answering. Can you pls tell me how to join the Discord ? Do not know what is and how to join

This is Zeal 8-bit OS, the official operating system for the Zeal 8-bit Computer, I invite you to check my other videos

There a still a lot of stocks out there, even in brand new condition. In the worst case, a reimplementation of the Z80 on an FPGA is also a solution.

@@Zeal8bit hopefully you still have some of these kits next week. That's when I SHOULD be ordering it. Super excited. Such a good learning tool.

Thank you very much for yoir support, it's very motivating !

If you are referring to the 98 pin ISA edge/slot connectors, these are not 8-bit but 16-bit, they take a lot of space and require a lot of signals that would be unused by the Z80 and Zeal computer in particular. I haven't seen any standard 8-bit ISA for the Z80 🤔

no, the one with 62 pins, 8bit Isa slot. yes it is big, but you can use all 8 but retro hardware, floppy controller, Soundblaster etc. like the drama PC from the 8 bit guy. my dream PC is a Z80 with ISA Slot and Soundblaster, VGA, rs232 lpt😊

This, I mean de.wikipedia.org/wiki/XT-Bus-Architektur@@Zeal8bit

Actually I implemented a PSG: 4 voices than can all generate triangle, sawtooth, squares waves and noise. There's also a sample table to generate arbitrary sounds😄 They are several open-source Z80 Forth out there, it shouldn't be too hard to port one of them

@@Zeal8bit We've discussed it elsewhere ;)

I find CP/M igreat but limited for a modern 8-bit computer. For example, it doesn't support directories nor multiple filesystems. It did inspire me for Zeal 8-bit OS though 😉

Thank you very much! The Z80 makes it simpler than it sounds thanks to it's simplicity (no cache, no pipeline!)

Спасибо!

I was more inspired by Linux but yes, technically it's also a DOS 😄

​@@Zeal8bit it lacks the fun part of unix-like system - multitasking, for me it looks more like DOS, and it's not bad!

@@LiveGameDriveChannel Good point! We can see it as a DOS then yes 😄

Thanks for your comment! No problem, take your time, I also wanted to make something simple but making games is very time consuming😄

Thank you very much for your comment! - In text mode, the scrolling is done character by character, not pixel by pixel. This list was shown using the 640x480 text mode - The 16 colors for the text mode are the first 16 colors of the palette. In fact, the 256-color palette is shared between all the entities: text, tiles and sprites. - Sprites are only available in graphics mode. It's always possible to simulate a text mode in graphics mode with 16x16 characters though 😄 - Sprites are also 16x16, just like tiles. The tileset is shared between both tilemaps (foreground and background) and the sprites. - It's hard to say because there is a lot of parameters that enter into account. From my calculation, in the worst case, we should be able to show up to ~40 sprites per line, which represents one line completely filled with sprites (when in 640x480) - In this version of the prototype, there are two pins that go from the FPGA to the Z80 PIO, one is for V-sync and the other one is for H-sync. However, in the release version, I plan to re-use one of them as global FPGA interrupt (an internal register can give the cause/reason of interrupt). But of course, I will keep the possibility to trigger and interrupt on both v-sync and h-sync. Moreover, there is already a register that lets the program get the current raster position, as well as two bits for h-sync and v-sync status. - The video board doesn't provide any accelerator since these transformation would make more sense in a bitmap environment. I don't exclude the possibility of having such feature in the future though. One of the feature that would love to make and would make more sense to me would be a tiny coprocessor, similar to the Copper on the Amiga. HDMI is a proprietary connector, any hardware board that provides one needs to pay royalties. If I updated the board to have a digital output, I would choose DisplayPort (or DVI maybe?) since it's license-free. My screens all have VGA input, so I have never tried the VGA-to-HDMI converters (I should though)

​@@Zeal8bit DVI or DisplayPort are both great alternatives. DVI-D in particular converts very easily to HDMI. Other projects have provided HDMI-compatible output using the HDMI connector, but have evaded the licensing issue by simply not using the term "HDMI". In one case it was labeled as "IMDH," and I fully support the idea of having people ask salespersons if their TV or monitor is "IMDH-compatible." :) A (tiny?) graphics coprocessor would be a truly excellent idea. The reason I asked about pixel scrolling and sprite support in text mode, is that this makes it very easy to recreate or port older games that essentially use the character set as tiles. But you're correct in that the existing tile modes do this better, and also one rationale for using text screens as tile-based graphics on older 8-bit platforms was to get around the memory limitations of the system. This is obviously not an issue with the Zeal 8-bit.

To overcome both the memory usage limitation as well as the slow CPU speed. The Z80 is a very slow CPU in comparison to what we have today. In the best case, it takes 7 clock cycles to write a byte to a given memory address. Imagine if you have to write 320x240 (= 76800) pixels for each frame, it would take more than 500 000 clock cycles! At 10MHz, this represents 53ms, so at best we would get 18FPS. With tiles, with a single write byte in VRAM, we can update 16x16 (=256) pixels shown on screen, so we can reach 60FPS

@@Zeal8bit How dare you? Z80 is the best in a world 😉 A long, long time a ago... I knowed bytes of most popular instructions in my head and manually assembled many experiments on my ZX81 🥲 I admire your realisation of my dreams. I wondered if such card don't have space in FPGA to implement some blitter functions: filling rectangle, copying rectangle, moving rectangle. Also from experience with C-64 VIC very useful is posibilty to "scroll" whole picture or plane 0-7 bits without any memory operations, this gives slow CPU chance of do some animation on memory. I suppose fast buffers switching is already implemented. 128 sprites is very impressive.

@@AK-vx4dy I agree, the Z80 is the best! 😄 In theory it would be possible to implement such blitter functions, but this would complexify the implementation of the tileset and tilemap. One thing I would love to implement is a tiny coprocessor, similar to the Copper on the Amiga. But this requires some time. In 640x480px mode, the hidden part of the screen is as big as the visible part, so a program can use the hidden part as a framebuffer and swap the visible part by simply changing the scroll value (two instructions) In 320x240 mode, the hidden part is even bigger, so you can see it as one visible framebuffer and seven (!) hidden framebuffers. Again, changing the X and Y scroll values can let a program change the hidden buffer

@@Zeal8bit I understand this complication so my idea was to ditch tiles in favour of simple blitter functions. Wow Cooper would be amazing feature ☺ In my scroll 0-7 pixels I mean something not really affecting existing image generation but rather starting generating whole line sooner and mask it with border without changes in tiles etc.

​@@AK-vx4dy I find that getting rid of the tiles and replace them with simpler blitter functions, the video board would result in much more "primitive" graphics. Don't you think so? Instead of SNES-like games, we would have Vectrex-like ones.