| Re: Z80 Multi Board Computer [message #9941 is a reply to message #9891] |
Mon, 30 May 2022 05:56   |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Hi
The PCBs arrived for the Z80 VDP1A and VDP1B boards. Both have been built and tested. They both produce composite video and RGB just fine. The VDP1B also produces S-Video. They seem to work OK.
The VDP1A works without any modifications although I have not gotten it to work with the GBS-8200 as I had hoped. Dan has gotten his working with a composite monitor and an SCART-to-HDMI converter box. The GBS-8200 *sort* of works but the image is really dim and jerky ( sync is unstable). Not sure why this is because the GBS-8200 works great with the VDC using the same input signals. Regardless if the GBS-8200 wont work reliably then the SCART-to-HDMI can replace it. Possibly with more experimenting we could make the GBS-8200 work but not sure if it is worth it since it's been a PITA for a while now. Here are the parts for the SCART-to-HDMI and HDMI-to-VGA converters
https://www.aliexpress.com/item/2251832672241216.html
https://www.aliexpress.com/item/3256802396960028.html
https://www.aliexpress.com/item/2255800390712387.html
https://github.com/lynchaj/nhyodyne/tree/main/Z80VDP1A
The VDP1B seems to have more problems and requires three patches to work. It has the same GBS-8200 issues as the VDP1A so will use the same converter. It does work though which is fortunate.
The following patches are needed (per Dan's build. Mine are similar but slightly different):
- HSYNC (pin 5, U12) needs to be low, not floating I tied it to pin U12,Pin 1 with a jumper
- SCIN (U5) needs the CLK signal, and this is disabled when JP1 is off (which it typically must be off in order to not conflict with the system clock 
-- I clipped pin 12 on the bus connector and installed JP1
- R, G, and B need 470 ohm pull downs to ground from pins 22,23 & 24 on the VDP (U3)
Of the two designs, I think the VDP1A seems to work better although with a respin the VDP1B might be slightly better since it can produce S-Video in addition to composite and RGB. My converters are still awaiting delivery so I haven't completed my own build and test yet.
Thanks, Andrew Lynch
[Updated on: Mon, 30 May 2022 06:02] Report message to a moderator |
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| Re: Z80 Multi Board Computer [message #10256 is a reply to message #10251] |
Tue, 21 February 2023 04:49 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Hi
The redesign of the modular backplane computer seems to be going well. Incorporating as many of the lessons learned from the last system as possible. I am finding that the slightly larger boards with a higher level of integration is paying off well in terms of reducing part count and ultimately fewer boards will be needed for a basic system.
There are four boards in work at the moment, 1. an expanded backplane, 2. a Z80 processor with DMA built in, 3. ROM, RAM, & RTC NVRAM, and 4. input/output based on the old Zilog Peripherals (CTC, SIO/0, dual PIOs).
The new system will include a timer function and use IM2 as the default. The expanded bus includes many more interrupts and some user defined pins. The 16C550 UARTs are great for speed but the SIO/0 integrate much better with the Z80.
You'll need KiCAD to really explore the system. Looking for any input people might have and/or discussion.
Thanks, Andrew Lynch
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| Re: Z80 Multi Board Computer [message #10257 is a reply to message #10256] |
Wed, 01 March 2023 05:08 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Hi
Still working on the nhyodyne redesign. I have a number of changes to make before I upload a new version of the zip file. It should be soon though.
There are a lot of differences to the nhyodyne. First, there is a much larger bus with 150 pins spread over three 2x25 IDC connectors. This requires a significantly larger board that allows for a slightly higer degree of integration. There is some consolidation of the nhyodyne boards at about a 2-to-1 ratio. Also using GALs to consolidate miscellaneous logic chips and reduce part count, complexity, and cost
Boards in work at the moment:
1. board template, used as a basis and tool for subsequent designs
2. 8 slot backplane with 18mm center to center spacing (addresses potential board to board contact issues with nhyodyne)
3. Z80 processor with DMA and extended IM2 interrupt support (no over-the-top connections for interrupts)
4. 1MB ROM/1MB RAM board
5. Zilog peripherals, used as main console including 2 serial, timer, and dual parallel GPIO
6. Multi IO, contains several useful functions such as DUART, bidirectional parallel port, PS/2 keyboard & mouse controller, and USB/SD controller
I would really like your input on this system. My goal is to simplify nhyodyne so you can have a nice homebrew computer using about half the number of boards required by nhyodyne. Significant part count, complexity, and cost reductions by sharing common functions such as bus buffers, IO port decoders, miscellaneous logic, bus connectors, etc.
Everything is being done with free/open software such as KiCAD for EDA and Digital for PLD design
Please contact me if interesting in participating. This is a small group discussion for now while the concept matures.
Thanks, Andrew Lynch
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| Re: Z80 Multi Board Computer [message #10259 is a reply to message #10257] |
Sun, 05 March 2023 09:28 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Board Template (doubles as a prototyping board). There are three 2x25 keyed, shrouded, right angle bus connectors at the bottom of the board. They are offset in such way as to make reverse installs or "off by one" mis-installs very difficult. The middle connector is 2 mm closer to the left connector than the right one although it is hard to tell in the image. The shrouds and keying should make reverse installs much less frequent.
NOTE: Board renders are notional and still in-work. Final details on PCB layout have not been settled yet.
[Updated on: Sun, 05 March 2023 09:35] Report message to a moderator |
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| Re: Z80 Multi Board Computer [message #10261 is a reply to message #10260] |
Sun, 05 March 2023 09:33 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Z80 Processor board with DMA, IM2, and wait states support. Uses PLCC-44 Z80 CPU and Z80 DMA. IM2 includes 8 additional extended interrupts in addition to ~INT0. Board includes spare sockets for patching during prototype phase. Will be removed for final, debugged version.
[Updated on: Sun, 05 March 2023 09:43] Report message to a moderator |
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| Re: Z80 Multi Board Computer [message #10262 is a reply to message #10261] |
Sun, 05 March 2023 09:38 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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ROM & RAM Memory Board. 1MB Flash ROM and 1MB SRAM. Uses memory pager from Sergey's Zeta2 design. Updated to support more modern memory parts. Includes configuration NVRAM RTC with basic user inputs like LEDs, button, speaker, etc. Single CR2023 coin cell battery for both SRAM and NVRAM RTC battery backup.
[Updated on: Sun, 05 March 2023 09:39] Report message to a moderator |
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| Re: Z80 Multi Board Computer [message #10273 is a reply to message #10251] |
Wed, 15 March 2023 09:35 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Quote:Hi
Doing more updates on a redesign of nhyodyne. If you are interested in a generic hobbyist bus retrocomputer project please join the discussion at nhyodyne. I've placed the project KiCAD files here:
https://github.com/lynchaj/nhyodyne/tree/main/!REDESIGN
Thanks, Andrew Lynch
Hi, made a major update yesterday and to the design file set on GitHub. Getting much closer to a buildable state. Out for review & comments now. Looks generally OK but probably some significant changes to processor and memory board reallocating the memory mapper function. It makes sense and would result in a more CPU-generic memory board. Still some Z80-centricity but you'd expect that given its heritage.
File set includes PDFs and PNGs for design information, but best tools are loading in KiCAD and/or Digital (for the PLDs)
Thanks, Andrew Lynch
PS, I checked with JLCPCB and while the new boards are more expensive on a per-board basis, each of the new boards are replacing two or more of the old boards so the cost difference of the new boards is about a wash or maybe a little better value. However, due to the consolidation of functions (two or more single function boards to each new format board) the overall part count is reduced. Plus, there is now room for additional capability that could not be supported before due to limited PCB space. A significant net gain in cost reduction by lowering part count. Use of PLDs has further driven down the part count allowing more things which were impractical before.
[Updated on: Wed, 15 March 2023 10:34] Report message to a moderator |
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| Re: Z80 Multi Board Computer [message #10287 is a reply to message #10273] |
Fri, 24 March 2023 15:15 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Hi
Still working on the new duodyne board set. Would really appreciate any feedback on the design files. They include the KiCAD and Digital sources which you can use in those programs. PDFs of schematic and PCB layout along with a JPEG of 3D rendering.
There are many changes since the last file drop. Now the processor board includes a serial port, so the minimum board set is now only three (4-slot backplane, processor, and ROM & RAM board). There are so many changes it can hardly be considered a nhyodyne redesign anymore and really is starting to evolve into a new project with some nhyodyne heritage.
Files can be found here:
https://github.com/lynchaj/nhyodyne/blob/main/!REDESIGN
Please take a look and post here or send me a message. Thanks! Andrew Lynch
[Updated on: Sun, 26 March 2023 06:16] Report message to a moderator |
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| Re: Z80 Multi Board Computer [message #10362 is a reply to message #10361] |
Wed, 17 May 2023 04:28 |
lynchaj
Messages: 1051
Registered: June 2016
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Senior Member |
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Hi Edzard
The files on the nhyodyne GitHub repository are the latest. However, based on lessons learned and feedback from nhyodyne I've moved development over to duodyne as its successor.
Although there are fewer duodyne boards than on nhyodyne, there is greater integration so fewer parts overall are necessary. Each duodyne board is roughly equivalent to 2-3 nhyodyne boards.
Some of the future boards I was planning for nhyodyne are only appearing on duodyne such as the Propeller + ESP32 board. Some boards that wouldn't fit on nhyodyne like the uPD7220 graphics board are on duodyne also. I am trying to have a diversity of mass storage options to include SD cards in addition to CF, Flash, IDE, Floppy drives, etc.
I am really looking forward to building, testing, and debugging the core system to get started on some of the new boards. I think the new larger bus will make adding other CPU architectures a lot easier.
Thanks, Andrew Lynch
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