Yeah, I wouldn’t want to write a soft UART if I could avoid it. :) Thanks for the info!
On Sat, Apr 25, 2020 at 7:47 PM Stephen Adolph <twospru...@gmail.com> wrote: > 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 >> >
