Why not wire dsr from the printer to CTS On Fri, Jun 9, 2023, 5:23 PM Charlie Hoey <charlie.h...@gmail.com> wrote:
> Apologies for the longish post, didn't have time to write a short one! > > *TL;DR* I've been happily serial printing on my 100/102, but my 200 > doesn't work, so I'm in search of a non-hardware solution to tying DTS/RTS > together on a 200 to let it send RS-232 data. > -------- > I've been experimenting with RS232 printing on an Apple Imagewriter ii, > and I noticed that my 100's and 102 will print to it just fine, but my two > 200's both just time out trying to print (by print I mean, save a text file > to "com:88n1enn". Same deal when just playing around in the terminal, it > gets a little buggy and I can't even quit without powering on and off, and > identical behavior on both otherwise healthy 200's. What gives? > > I dug around the m100 list archives, and there's this thread from 2015 > http://lists.bitchin100.com/htdig.cgi/m100-bitchin100.com/2015-January/069836.html > that's very similar (also this one > <http://lists.bitchin100.com/htdig.cgi/m100-bitchin100.com/2018-May/077378.html> > and > this one > <http://lists.bitchin100.com/htdig.cgi/m100-bitchin100.com/2013-January/065432.html>, > an old problem). So I hooked my 102 and 200 up to a scope and made a > little test harness to look around, and long story short, the 200 indeed > refuses to send any RS232 data unless RTS/CTS are tied together. This > doesn't seem to be the case for the 100 and 102, which will happily send > data out blind. > > Digging through the Technical Reference Manual > <https://ia801908.us.archive.org/14/items/Model_200_Technical_Reference_Manual_1986_Tandy/Model_200_Technical_Reference_Manual_1986_Tandy.pdf>, > the 200 does indeed have a different chip (82C51A) for handling serial IO, > and perhaps it is pickier about when it allows outbound traffic. The TRM > has what amounts to a decent data sheet on that chip, and this part caught > my eye (bottom of pdf page 98): > > [image: image.png] > It seems like perhaps it's possible to fix this with software? Or, am I > way overthinking this whole thing, and there's another way to do it that's > even easier? I know I can just get a null modem cable, but it's kind of a > bummer to have to get all new cables to use a 200 with printers the 100/102 > happily connected to. > > Thanks for reading / any advice. > -Charlie >
