rcj@burl.UUCP (R. Curtis Jackson) (03/16/84)
I just read the article in question, and decided to try it. I have a vt102 (vt100 lookalike) from DEC; I normally run 4800 baud. Sometimes I run 9600 baud by doing an 'stty 9600', which gives me a bunch of screwy characters for a prompt back; I go into setup mode and changle the receive and transmit speeds on the terminal itself to 9600, and when I get out of setup mode and hit return I get a normal prompt and am running at 9600 baud. I used the exact same procedure for 19200, I typed 'stty exta' and got NOTHING back; after a while I went into setup and told the terminal I was running at 19200, then came back and still nothing. No response to <cr>, <del>, or <break>. I ended up having to reset my terminal to force Unix to run another getty. Oh, forgot to mention, I am running USG Release 5.0 on a VAX 11/780 with DZ11 and KMC11 assist. Any ideas? -- The MAD Programmer -- 919-228-3313 (Cornet 291) alias: Curtis Jackson ...![ floyd clyde ihnp4 mhuxv ]!burl!rcj
grt@hocda.UUCP (G.TOMASEVICH) (04/16/84)
On our system, VAX 11/750 USG UNIX 4.2, dz11 with kmc11 assist, the 'stty exta' does work. It is noticeable in watching Blit programs download.
mcferrin@inuxc.UUCP (P McFerrin) (04/21/84)
I did some investigating of 19.2 on DZ11"s. My work was done on USG 5.0.1 so if you're running something differrent, this may or not apply. I tested several of my DZ11's to see if they would indeed work at 19.2KB. I discovered that systems running DZ11's WITHOUT KMC11 assist will NOT work unless a change is made in the driver (dz.c for those who have source license). There is an internal speed table that converts the 'standard' baud rate values (e.g. B300, B1200, EXTA, etc) to values appropiate for the line parameter register of the DZ11 line. The entries for EXTA and EXTB are zero which will set the baud rate to 50 baud. The driver for the kmc11 assisted DZ11 (dzb.c) have a value of 017 for both EXTA and EXTB which selects the 'NOT USED' baud rate (according to the DZ11 Users Manual). Data is indeed xmited at 19.2. I ran some tests to see if the KMC11 could keep up with this baudrate. I started up 8 processes (each on a different line, same DZ11/KMC) that was i/o bound (constantly writing the same buffer repeatedly). These programs calculated their own thruput and ALL OF THEM attained 19.2KB thruput (VAX 11/780). The CPU was kept busy about 60-70% of the time (mostly in kernal mode). I repeated the test on a PDP11/70 without KMC11 assist. I could only start 3 processes and retain the 19.2 thruput. Just one process alone caused the the CPU to be busy 98% of the time! We have not made any use of 19.2kb in any of our applications. I was just attempting to verify what I was reading on the net. There is still the issue of official DEC support. The only impact (related to maintenance) I can see that 19.2 may have is the EIA driver/receivers may be marginal for A PARTICULAR INSTALLATION (e.g. cable type/length) that could possibly lead to future problems that can ONLY be duplicated at 19.2KB. In this situation, DEC probably has the right to say "we don't support the DZ11 at 19.2". Of the few DZ11 failures we have have, none have been related to EIA receiver/driver problems. There is however always the possibility that this 'NOT USED' feature might dissappear in some future revision of the DZ11 board. Paul McFerrin