Smart framebuffer chips for the HEC
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- čas přidán 10. 11. 2022
- If you want a short answer to the thumbnail question, it's NO. Smart framebuffer chips for early 8-bit computers are very primitive and mostly geared towards text-based and CAD programs instead of games.
The video chip of choice for the HEC is the V9958 which combines a tile-based graphics engine and a game/demo-oriented smart framebuffer. However, HEC being HEC, these are still very good options for third-party add-on cards! - Věda a technologie
I can tell you exactly what chip you need for video: Parallax Propeller I (P8X32A-D40) in 40-pin DIP. Now once you got that you can also emulate Z80 at a good speed - but you don’t have to.
Prop I makes an excellent I/O accelerator. One chip gives you lots of software defined hardware: VGA output, math acceleration, audio synthesis, PS/2 keyboard and mouse interface, and more.
It’s a specialized 8-core chip that is great for those tasks. It has little memory and a specialized architecture so it’s not great for application development, but as an offload engine it really shines. It’s probably the most modern retro chip you can buy, still in production.
It can easily replace all of the peripheral chips a typical Z80 computer would have: video, sound, parallel I/O, UART. It can also generate composite NTSC and PAL - probably for two screens at once if you want. A single P8X32 dedicated solely to graphics gives you low-end shader programming and stuff like that. You can definitely do low-rez 3D graphics with it. For 2D graphics it can do lot or less anything any retro 2D hardware did - sprites, scrolling, blitting, tiles graphics, etc.
If you asked me to put together an “ultimate” Z80 system I’d toss two P8X32As in it. One for graphics, one for everything else, a Z80, 1M of RAM, and have the whole thing boot off a 2nd SPI EEPROM - the first would boot the “master” Pripeller. 6 chips, very little glue logic if any, single clock.
I have experienced with modern 'smart frame buffer' chips for graphics - the two best ones are the RA8875 and SSD1963 - they are designed for digital output.
However - they would give you lots of graphics capabilities without requiring much from the processor
Those ideas are super intersting. Modern chips are out of my common scope since I just don't know their name. There may be future HECs with digital video output. If not, HEC being HEC, you can always build a digital output graphics card.
@@andyhu9542 - At the very least until you find your ideal graphics solution? you can get a screen with an RA8875 built into it and chat to it using its very simple SPI protocol. A VT100 compatible serial console is also a good start. That SSD1963 chip is very cool too - both chips have SPI and parallel interfaces. (they have their own memory/framebuffers and are drawn to with commands, so there's zero requirements to have full high res graphics other than SPI)
The chips are often pre-paired with a screen or a controller board - but the chip is available on its own where you can properly exploit the parallel communication and ignore the touch controller :P
ooh! the RA8875 has a built in character ROM and allows for external character ROMS for different languages - so you get easy high-res text right out of the box!
Love your videos - hope you're well :)
Maybe not correct time period but there is a modern chip that does almost the same as some old video chips of the 80s from FTDI, serie named EVE(Embedded Video Engine) FT8xx
Those chips are very nice for 2D-graphics, but takes a while to get your head around. I use one with my 65C02-build.
I'm interested. What are the functions of the chip? Is it for text only or for graphics?
The top FT8xx chip looks really good! native 800x600 is super interesting - the problem however is the same as the RA8875 and SSD1963 - they only naively support a specific digital interface of flat screen displays. It may be very difficult or even impossible to use them to drive analog/VGA or HDMI.
@@andyhu9542 - if the FT8xx series, or the RA8875 / SSD1963 allow for any size of screen? it may be possible to 'simulate' a digital screen of a lower resolution so that the pixels are built up in some SRAM instead of on a digital flat-panel. Then you'd be able to use the convenience of these chips while still having a system-side shadow of the framebuffer for more conventional analog display methods.
Or you could just limit the computer to digital flat-panels for the main display - not really a big problem, they're very cheap and will look good on youtube.
Plus it'd be super easy to share input/output between a serial terminal connection and the code that sends commands to the FT8xx/RA8875 chips - so if you're going to have serial anyway? you can integrate the RA8875 over SPI at the same point in the kernel - giving you powerful graphics that sit nicely in the serial terminal part of your kernel, easy to add, easy to remove when you've got something better :)
@@andyhu9542 The chips are 2D-accelerators and can deal with sprites, text, different bit-depths and layers. 1MiB RAM and SPI interface. There are LDC/chip combos available and also Arduino-hats with VGA/HDMI out only. Lots of code and libraries ready.
Still trying to decide on a video chipset, eh?
What about using a second dedicated z80 only for graphics? Make your own z80-GPU? Maybe keep the VRAM on a separate bus so you could send it a "draw rectangle" command, and it could do the framebuffer filling, without slowing the main processor doing other tasks?
tons of projects struggle with the video chip choice - all look at old chips at first - then end up using something new or making their own inside an FPGA. I'm a big fan of the RA8875 - it gives you powerful graphics for very little effort - but you are restricted to digital displays
You won't believe how far I took this idea: a quad 6502 GPU running in some sort of SIMD, yet this type of ideas takes too much board space and was considered a total overkill. HEC being HEC, I'm looking forward to some third-party cards with their own 6502 or z80!