Astal4

Revision zero motherboards arrived!

I'm planning on building one of these systems, my 1040STF is a pain in my ass even with the fixes, it just isn't a stable system, I do BGA work sometimes so I don't see much of an issue with assembling one of these, is the ST ATX better than this? I have a 50MHz 030 board I want to throw in but it just won't work in my 1040 so I'm debating between a few.

For stability, would possibly replacing the 80C88 with a higher rated one allow it to run stably? I don't know exactly how the video system works but it might be CPU driven being a monochrome DOS machine. There's the 10MHz OKI 80C88 which could be swapped on.

My implementation for dual CPU was going to be a DMA system from the video Z80, a ROM with built in functions for it, and an IO space register bank for control. FPGA is the system I'm thinking of going with since I need one for my sound chip anyways.

There's a couple ideas up in the air for video, the major two are a second Z80 with a firmware to do graphical tasks, or an FPGA core with an era appropriate sprite engine in it. Sound will also be on the same card, the same implementation as my 7800 wavetable sound chip that I am working on.

I'm sorry, typed it late, Z84C00, Z84C20, Z84C30, and Z84C40

Full Zilog chipset being CPU (Z84C00) + PIO (Z84C020) + CTC (Z84C030) + SIO (Z84C040) The details are still somewhat TBD, but here goes. 10MHz clock speed Hot plug serial data cards as an analogue to floppy diskette 4 expansion slots 1 higher DMA priority video expansion slot RAM slot with support for up to 512KB RAM, possibly will increase to 1MB or 2MB if I see it needed CP/M Plus BIOS, will run CP/M 3 out of the box via the onboard RS232 port, or a custom TBD mouse driven OS, built for CP/M 3 platforms. Built in keyboard controller (8 rows by 16 columns) Built in "serial expansion" slot for things like MIDI, joystick breakouts, probably mice, and other serial devices, with baud rates from 31250 to up to 2M. TTL level Built in RS232 serial port Up to 10Mbit/s serial speed for serial data card, size will likely be 512KByte, aim to write a floppy diskette compatibility layer in BIOS for it.

Project is dead, however! There is a "Saturn" computer project that I have developed to a CAD schematic so far within the past few days, I think I'll be spinning up some boards soon. Completely new, unrelated design, it uses a full Zilog chipset on the mainboard with all 74 series logic minus a MAX232 and the ROM, RAM is a daughterboard... More details coming soon if anyone's interested.

Interesting, however I'm going to be building a hardware video system rather than using an ESP32 or something, it's going to be more in the 80s style, but I might pick one of those up to play with. This project is somewhat on the back burner right now as I've fallen in love with the Apple Newton for some stupid reason.

So the "blitter" will just be a block transfer, can be used for anything, no specific sprites, but can move things around memory quickly, I'll likely set it up to address and move pixels around. The hsync interrupts i could look at adding as well. The fun part of using an FPGA for logic is I can add all this in progressively. 8 bit computer, although the base form could easily be used as a console since the keyboard will likely be PS/2 detachable. It's just strawberry because I'm a music nerd I'll likely be calling the expansion cage Penny Lane.

Thanks! So the palette is the full RGB555 spectrum to choose from, or 32,768 colors, the color modes are 8 bit, 4 bit, and 1 bit, so 160x120 has 256 colors, 320x120 has 16 colors, and 640x240 has 2 colors. There's a look up table in RAM for the colors, 512 bytes on top of the screen buffer, where you put the color values, any 256 RGB555 colors. I could increase the video RAM though, the specs are tentative so lots of fun to be had with features. Thanks for the kind words.

Thanks for the kind words. It will not be compatible with any other 8 bit, as it is a completely new system. An emulator would be possible. I HEAVILY recommend the programmers to use the programmable interval timers for timing rather than the CPU clock for reasons which I'll share in the near future.

Thanks. The reason I chose 160x120/320x160/640x240 is they all integer scale to 640x480 so a non multisync VGA monitor can be used. The expansion connector is a Euro-DIN 96, it's cheaper than a big S100 style connector, for people to purchase, I would love to get this into the hands of developers and get some games going for an official launch. I have rough sketches of the case design and I would love to injection mold them but cost, so I can't do everything. But I'm hoping this is a fun machine for people.

Hello! I'm.. Announcing? I guess... A computer system I'm working on! I was personally very disappointed in the Commander X16 (Commodore derivative), MEGA 65 (Recreation at a high price), and am not too interested in the ZX Spectrum Next (Enhanced clone) or any of the other systems that are either clones or derivative of older ones. So I'm creating my own. It's currently just the codename "Strawberry" as in Strawberry Fields Forever. The tentative speclist is... Z80 @ 8.39MHz A floating point coprocessor (either an AM9511A-4 or something custom built by me) A "Programmable Block Transfer Unit" (Basically a blitter but I want to be fancy), aiming for 16.78MHz 128KB system RAM 19,200 byte framebuffer for 3 video modes (160x120x8, 320x120x4, 640x240x1) 8 oscillator 8 bit wavetable sound 4 system timers DMA enabled system Cartridge port, expansion port, and RGB video, along with an internal speaker and a 3.5mm output VGA video output PS/2 keyboard input 2 joystick ports (fully digital ports) This is my major long term project, and I will be updating as I continue. I will be working on this over the course of likely at least a year. I would also like to be building a companion expansion cage for it, and a custom operating system. My goal is to be able to offer the system in a kit form for $99, but I can't promise anything with it being so early in development. I'd love to get this to a prototype stage and see what some of the talented developers here could do. Wondering thoughts. I know these systems never take off beyond maybe 2 or 3 people who think it's cool but eh, I'd love to get something into the community and have a machine that's straight up fun to play with, with all new parts, that's accessible to users interested in the modern retro scene or in the modern retro scene but don't want to make a huge investment into something like a C65 or any of the other far more expensive machines. Thanks everyone and have a great day!