Model 100 UART is able to clock at 9600 19200 38400 and in fact also 76800. Model 100 is very hard pressed to use the existing rom routnes to utilize 38400. There's just a lot to do to process input bytes using the circular buffer etc. I myself have passed characters between two m100 at 76800 by manually coding, but It was flakey because of how you have to set up the UART.
Combined with the fact that the fastest common rates on a PC is 19200 then 38400 then 57600, the internal UART cannot run 57600. So for PC file transfers, the M100 is limited to 38400 at best (unless using BCR at 57600). Also, it is not possible to take over the serial port interrupt. It is hard coded with no hook. So, to use the UART fast you need to poll it. I suspect that makes it more or less like what I have done here.... dedicating the CPU to the read in process. But it would be at best slower than the BCR port. If anyone is interested I can post the code on the wiki. It was fairly difficult to get it to work. I really had to manipulate it. On Sat, Apr 25, 2020 at 10:27 PM Tom Wilson <wilso...@gmail.com> wrote: > I’m curious... why is this faster than the UART feeding the real serial > port? Bit banged I/O should always be 1/10 the speed of a UART, unless the > UART is broken or something. > > On Sat, Apr 25, 2020 at 7:25 PM Stephen Adolph <twospru...@gmail.com> > wrote: > >> Still playing around with the BCR TTL serial port. >> ...yes it has it's limitations... half duplex, no flow control, bit-banged >> >> ..but it is fast! Today I was able to get 32kB transferred in 7 >> seconds. That's pretty close to 100% utilization on the 57600 baud line. >> >> I think that is a new M100 record. It might need independent >> verification! >> >> (why? to reduce time for CP/M disk backups. 4MB will take a 1/2 hour >> with this approach, or more than an hour at 19200 baud.) >> >> Steve >> > -- > Tom Wilson > wilso...@gmail.com > (619)940-6311 > K6ABZ >
