@emard I like how fast it boots and gets prompt, even exe's are short, responds fast to prompt and only 6 MHz 16-bit CPU. Wonder are elf, ld, systemd all only to counterbalance for GB of RAM and GHz of CPU...
Well, the PDP-11 was a 6MHz 16-bit machine and the VAX 750 ran at 8MHz. That is the hardware both Unix and the Internet were invented with. Unix has had
ld since the earliest days. I don't care much for
systemd which is trying to do entirely too much - but at the same time
init is too simple a solution for a world with pluggable hardware.
elf (or at least dynamic libraries) are a good idea in a bigger memory space. Without it, V7 Unix has about 5KB of stdio code duplicated in dozens of binaries - surely that is not quite right either.
ls -alh /usr/bin/nextpnr-ecp5 -rwxr-xr-x 1 root root 111M kol 2 05:32 /usr/bin/nextpnr-ecp5
@emard Instead of 9600 I'd like to have 115200 ... :)
That is 12 times the speed. If we hook up h/w handshaking it is possible as a minimal fix, but that of course will not get your throughput up much. The problem is that the 9902 interrupts once for each character sent and received: at 12 times the speed the CPU would have a hard time to keep up. However, other manufacturers (read DEC) had I/O boards with buffers. It will not be too difficult to make a special UART chip in Verilog with buffers so that the CPU could R/W multiple bytes on each interrupt. What do you need it for?
Looked into early RTC chips. The first one seems to have been the OKI MSM5832, which was used on a few S-100 boards around 1980. It has an awkward 4 bit interface though. If I get around to a new SBC I will probably use the MM58167. The software interface is always the same: a bank of byte registers with the time / alarm / config data (and sometimes 50-100 bytes of nvram).
@emard I am not sure which chip the ULX3S uses. The crowd supply page says MCP7940 but the schematic refers to the PCF8523. Both seem to have the same "bank of registers interface, though. If you can provide me with a verilog module that connects to the RTC chip and offers a bus interface similar to that of MM58167 to the CPU, I will integrate it with the Mini Cortex and write the Unix driver for it. I am not bothered if the registers don't match in number or meaning with the MM58167.
It would be fun to have
shutdown -r working on a V6 :^)