Hardware vs Simh (and FPGA)

On Sunday, April 14, 2013 16:31:05 ben wrote: What you would need is an FPGA board, one or more SD cards (not SDHC or newer, but the 'old' type), and optionally a little board with the enc424j600 chip The de0 board from Terasic has the advantage that it already has an SD card connector onboard. But, if you want to add the ethernet stuff, for instance by connecting a PMODNIC100 from Digilent, you'd have to wire it - look at the pictures on my site how that looks. The Nexys2-1200 board (the 'normal' board is has a -500 FPGA part on it, which is too small really) would in comparison need a PMODSD to connect the sd card, and optionally again the PMODNIC100. There are lots of other boards as well, each with their specific strong points and disadvantages - but, these two are the most obvious choices, and both will easily run a PDP-11. Whichever board you choose, you will need the tool chains from either Altera or Xilinx. These are ~~4Gb downloads - and also somewhat complicated pieces of software to install and work with, so expect some trial and error. In theory, it should be possible to run the same VHDL on other brands of FPGA as well - but I never tried. I do provide bitstreams, ie. pre-compiled binaries of the FPGA configuration, for some of the most basic variants. You still need to use the toolchains from the vendors to program these into the FPGA. And if you want to have a configuration that I don't provide a bitstream for, then you'd have to change the top level source and recompile - in most cases, that's not more complicated than changing a parameter on a macro, but it will require some time to find out how that works. The sd card (as I said) need to be the 'normal' type SD card, so anything larger than 2Gb will probably not work - those are likely to be SDHC or newer types. Currently, my VHDL design cannot cope with that. Also, there are probably some mistakes in the initialization sequence that I use to start the card, that sometimes cause cards other than Sandisk-branded ones not to be recognized - so, if you don't have any lying around, a Sandisk one is preferrable. And you'd also need something to write sd cards with - so, a way to connect an sd card to your pc. Any card reader will do. Then comes the detail about the console. The vhdl can be configured such that a simple console terminal is included on the fpga; in that case you would need a basic VGA screen capable of 640x480, and a keyboard with a PS2 connector. It's also possible to connect any basic terminal - or emulator - to the rs232 port of the Nexys2-1200 board, or wire up the solder connectors of the de0 board to do the same. Or use a PMODRS232. Anyway, to go back to the shopping list question, basically where it begins is the question of Altera vs. Xilinx. I tend to like Altera's stuff better, but that might change with the next release. Also, I think that Terasic's boards are produced to much higher standards. But - Digilent can get you all the things you need, and with Terasic you'd still need to find a source for the enc424j600 chip if you wanted Ethernet. Both vendors, btw, deliver directly and very reliably so. I think you can also get their products from Digikey and the like. Hope that's a clear enough shopping list for you :-)