Jump to content

dlv

6502
  • Content Count

    18
  • Joined

  • Last visited

Everything posted by dlv

  1. I came across the open source MNT VA2000 project last night (https://github.com/mntmn/amiga2000-gfxcard/tree/master) which brings HDMI output to the Amiga 2000. Is anyone aware of a similar project or efforts for Apple Nubus? It appears to me (naively) that the VA2000 could be leveraged for such a project. One of the main challenges is, of course, porting from the Amiga's Zorrow II/III bus to Apple Nubus. I've begun reading through "Designing Cards and Drivers for the Macintosh Family" as a starting point, just to get myself familiarized with the basics. However, I don't have an electrical engineering background or experience with FPGAs (always wanted to learn) to determine how feasible such a project might be...
  2. I've begun working on a schematic of the HDMI daughter board for the QMTECH FPGA, but I'm realizing that if I'm going to have PCBs made, it would make a lot of sense to wire in PDS (or NuBus), and save money and time... Guess I'll need to catch up and read the documentation you've all referenced. Stanford University (where I work) appears to have several of the "Inside Macintosh" volumes available, including one on QuickDraw, which I'm also curious about.
  3. That's great news, inkage? QMTECH's XC6SLX16 board available for sale from many vendors on eBay such as: https://www.ebay.com/itm/XC6SLX16-Spartan-6-Xilinx-FPGA-Development-Board-w-Micro-SDRAM-Memory-32Mb/264229717341 You can find the schematics, documentation for the board and its components, and example code FPGA code, under their GitHub project for the board here: https://github.com/ChinaQMTECH/QM_XC6SLX16_SDRAM I chose this board because it is the closest to the miniSpartan6+ used in the VA2000 project: Xilinix Spartan 6 LX16 (the miniSpartan6+ came in either LX9 and LX25; specs say the LX16 is closer to the LX25) 32MB of SDRAM 108 user I/O pins SPI NVM for FPGA bitstream and ROM For the proposes of this project, its only major shortcoming compared to the miniSpartan6+ is the lack of a built-in HDMI port but that could easily be provided by a carrier/daughter board. Of course, that means less than 108 I/O pins will be available for PDS/NuBus but there should still be enough? There is a DDR2 version of this board but I want to reuse as much of the MNT VA2000 project as possible (including SDRAM controller code for the miniSpartan6+). Anyway, I've been reading documentation of the three chips on the QMTECH board, understanding how it is all wired together, and comparing with the miniSpartan6+. The QMTECH board and Xilinx programmer are on their way. Baby steps... setup the development environment then see if I can program the board and blink some lights
  4. Hi - It’s a busy weekend so I haven’t had a chance to read or do much more research but on Friday evening, I think I found a cheap ($20) Chinese FPGA board on eBay that is comparable to the miniSpartan6+. It doesn’t have an HDMI port, so that will need to provided by the carrier board. That shouldn’t be any harder than the circuitry necessary to interface with PDS. In fact, I seem to recall from the VA2000 schematic, that the pins of the FPGA are just wired directly to the HDMI pins. I’m totally happy to pay $20 to experiment with this FPGA board. I think a great first step would be to wire an HDMI connector and see if I can get it to output something.
  5. I'll take a look at PDS but part of the motivation for me is doing this for a Quadra 950, which is the only 68k Mac I really care to collect. I imagine targeting the 68040 PDS is technically not any more difficult than targeting the 68030 PDS but there are likely to be other challenges, e.g., the '040 PDS connector, which is why I had been exploring Nubus. That's all; I don't doubt designing for PDS is a better route. I was speaking to the usability (i.e., UX/UI) of classic MacOS at resolutions beyond 1080p which, at pixel densities we're seeing on modern panels, might suffer. Which book are you referring to? It doesn't appear to be "Designing Cards and Drivers for the Macintosh Family (Second Edition)" (appendix B and C appear to be PAL listings). I did not mean to imply there's a problem - just my unfamiliarity with how PDS video cards interface with the system and vise-versa. As for the citation, I was mainly inferring from the "Additional firmware requirements of video cards" section (beginning on page 130) in chapter 8 of part I, in the book "Designing Cards and Drivers for the Macintosh Family (Second Edition)", which discusses the various structs necessary in the video card's ROM to enable the system to detect and use the video card. I just looked through the TOC but don't see an equivalent discussion for PDS video cards. That's a fine suggestion. Thanks. I want to temper expectations though - at this stage, I'm just trying to assess what would be involved and solicit guidance from more experienced people.
  6. Thank you all for the discussion so far. You mean, interfacing with the VRAM built into the motherboard (or whatever)? I doubt Nubus/PDS has enough bandwidth to pull the contents of VRAM at any usable frame rate. A FPGA board providing its own frame buffer to the system and outputting the video signal independently is definitely the way to go. Unfortunately, it looks like the miniSpartan6+ FPGA board used in the VA2000 project is no longer sold which is too bad because, from what I've gathered, it was particularly well suited for this type of application (and relatively cheap). There are some boards (DE10-Nano, Zynq-7010/7020) that appear to be suitable (HDMI port, enough digital I/O pins, enough RAM, NVM to hold ROM) but these provide ARM cores that, from what I've gathered, share the memory on these devices and are therefore not suitable for low latency applications. Some projects (MiSTer for the DE10-Nano https://github.com/MiSTer-devel/Hardware_MiSTer) have gotten around that limitation by attaching memory to the I/O pins. My recollection from skimming through documentation is that 56 pins are required in Apple's Nubus, which rules out the DE10-Nano, for example, because half of the 80 I/O pins available on that board would be used by the SDRAM daughter board. I haven't looked more closely at the Zynq-7010/7020 but I suspect it has the same problem. I suppose it's a possibility provided the FPGA has enough bandwidth. I agree. I think 1080p is probably the upper limit and there are still likely to be some issues, as you've pointed out. Nice find. It sounds like what the VA2000 is essentially doing, just... much slower. I'll check it out later. That's encouraging. I skimmed through the video card specific sections of the Nubus documentation the other night, and came largely to the same conclusion. I would be thrilled to have unaccelerated video; I think that would be a major accomplishment. Accelerated video can come later Right, I think one of the main challenges will be either finding a Nubus implementation with permissive licensing, or implementing one from scratch. And yes, I saw a bunch of level converters in the VA2000's schematic. I'll look into it. One concern I have is whether a PDS graphics card can be used early enough in the boot process? There's a length discussion about that in the Nubus documentation for video cards.
  7. Yeah... I'm not that nostalgic for old CRTs (been there, done that). My focus is on the machine, so I think getting a crisp 1080p signal from a Q950 would be a fascinating way to interact with it
×