diff --git a/README.md b/README.md index 8560648..0942adf 100644 --- a/README.md +++ b/README.md @@ -1,5 +1,43 @@ # NuXT1-MultiIO a WIP Multi-I/O card for the NuXT 1.2 XT clone from Monotech. - -Features: Parallel Port (Printer Port), Serial Port, TimeKeeper (Real Time Clock), and probably an extra internal serial port for the sole purpose of serving `pppd` to allow internet connection. \ No newline at end of file + +The hardware for this is licenced under the [CERN Open Hardware Licence Version 2 – Strongly Reciprocal](https://opensource.org/license/cern-ohl-s) +in line with the original licences from open hardware projects from which this project is +derived. + +## Features +- a TimeKeeper - a battery-backed Real Time Clock and nonvolatile storage, cribbed from [Aitor Gómez García's](https://www.aitorgomez.net) [RTC8088](https://github.com/spark2k06/RTC8088/tree/main) project. +- a Printer Interface, or Parallel Port - probably based off the original Printer Interface Card at this point, or possibly the IBM Serial/Parallel Card +- two Serial ports, corresponding to COM2 and COM3 - using the 16550 UART for higher-speed links, but based either on application notes or the IBM Serial/Parallel Card. +- one of the above Serial ports may connect directly to a RasPi Zero, either to provide a slightly more modern machine to `minicom` to, or to serve a `ppp` link for internet access. + +## Purpose +The v1.2 NuXT is an excellent computer with just a few missing features for convenience. The NuXT v2 +has improved on this, but there is still an installed base of NuXT v1 devices that can benefit from +a semi-modern multi-I/O solution; existing multi-I/O cards may also have features that are superfluous +or conflict with onboard peripherals. + +I (Horst Burkhardt) determined that what I primarily needed from an expansion card was a method of network +connectivity, (best served by a serial link), a parallel port, and that I would like a Real Time Clock. +If I can find documentation on the original IBM XMA (Expanded Memory Adaptor) or a similar card, I would +also be willing to add RAM on this card, in order to provide enough space for a RAMdisk. + +## Questions + +### Why not Ethernet? +An 8088 or an NEC V20 with half a megabyte of memory just doesn't need ethernet. Quite frankly, a 10Mbps +link will often work poorly on a modern Gigabit-capable switch. And I don't really relish making CAT5 +cross-over cables. +A serial link at 115200 baud, which is roughly where a 16550 tops out, is more than fast enough to +transfer files to an 8088. It's also a lot computationally simpler than managing an ethernet link, so +despite the potential for higher transfer speeds from an ethernet NIC, the real-world gains are dubious. + +### Why aren't you taking advantage of $(the hot new thing)? +Because I don't care. It's not important. This device must be reliable, simple to troubleshoot, and +most importantly, I have to understand it. +If a new device is compelling enough, I'm happy to try and work with it, but I'm not putting my name +on something untested and unproven. + +### Why are you like this? +Some very clever people have tried to work that one out, and failed. For now, you're stuck with me.