Carlos, I have a null modem cable.. It is basically a straight through RS-232 cable but with bins 2 & 3 swapped so transmit goes to receive and receive to transmit. My PC laptop does not talk RS-232 but does talk USB. I don't use the null modem cable.
I bought a USB to RS-232 using a female DB9 connector. https://www.amazon.com/gp/product/B0769DVQM1/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 ($11.99). You will need to convert a DB9 to DB25. This connector should work fine. https://www.amazon.com/gp/product/B07KVFCGT6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 ($5.74). After connecting the NEC 8201A to my PC, I found that the null modem was not necessary when using the USB to RS232 cable. I'd recommend starting with RS-232 communication to the machine using your favorite terminal program. Move a few programs to your computer. When you save the file, it will be a .DO. Load it into BASIC and then save it. The resulting file will be a .BA which is a tokenized form of your program. You can (and should) delete the .DO file at this point to save space. When you send a program to your computer, save it from BASIC with a ,A option to save as ASCII. (Save "MyProg",A). Now you will have a MYPROG.DO that can be sent back to your PC as a text file. I use 300 baud for receiving files and 1200 baud for sending them. You have to be patient, but it is an old computer. I've not had any luck with the cassette interface. Getting the levels correct is an exercise in frustration. My purpose in getting back to the Model 100/NEC PC-8201A was to do similar things you are planning such as writing (rewriting) BASIC programs. I've posted four of my NEC 8201A/TRS-80 M100 projects on github at www.github.com/LEJ-Projects. I've provided an article on each of these. I also have an interest in Arduino and old computers. I have a couple of Altair 8800 based on an Arduino Dual. I've learned (relearned?) 8080 assembly language and developed a 3D (rats eye view) of a 10x10 maze in assembly language. Perhaps I can convert it over to the TRS-80 Model 100 since the 8085 uses the same instruction set. I will first get the maze posted to some Altair groups. Anyway, welcome to the group. I'm a fairly new user myself and I have found people on this group to be very helpful. Lloyd -----Original Message----- From: M100 <m100-boun...@lists.bitchin100.com> On Behalf Of Brian K. White Sent: Saturday, January 29, 2022 5:30 AM To: m100@lists.bitchin100.com Subject: Re: [M100] New (again) Model 100 owner On 1/29/22 02:43, Carlos M. Nunez, M.D. wrote: > To answer the question of what I envision doing with the Model 100… > > The computer serves two purposes for me, the first being nostalgia. As I > mentioned, the Model 100 was my second computer, and I sometimes just like to > mess around and mentally time travel to my youth and the formative years in > my tech journey. I also like to code a little and mess with hardware a > little. I like to write simple programs in BASIC to teach myself things, and > I’m learning Assembly Language on my CoCo. > > I’m also a bit of a tinkerer and maker. I like to build circuits and robots > and gadgets, mostly on the Arduino platform. I have recently begun assembling > my own PCBs with old school EPROMS that plug into the CoCo cartridge slot and > can run programs or hold data. I 3D print a lot of the non-electronic parts I > use. All of that being said, I am somewhere between novice and competent in > most of the things I’ve listed. > > Now I have a few more simple questions to get me started… > > 1. Are there any recommended sources for a null modem cable? http://tandy.wiki/Model_T_Serial_Cable > I would prefer the PC end to terminate in a USB plug, so I believe it will > require a serial to usb converter somewhere. Also, any good online > information and/or tutorials that walk through the null modem cable file > transfer stuff? That is kind of a large question with a lot of different answers, and all answers are somewhat opinionated to the person answering. A full answer covering all bases is so much I'm just not going to bother, and instead I'll just say what I'd do. First, transferring files *conveniently* involves using a tpdd emulator. You install a tpdd client on the 100 and a tpdd server on the modern machine, and they talk to each other. There are several tpdd clients, several ways to get a tpdd client installed onto the 100, and several tpdd servers. The simplest and best way to get a tpdd client onto the 100 is to buy a REX#, and it has TS-DOS in rom. That makes life better in several ways. TS-DOS is the most user-friendly tpdd client, but it's one downside is it uses a lot of ram, except, if you have the rom version then it uses essentially no ram. And the REX#, having it in rom, means you never have to bootstrap it to get it installed. It's always available even after hard resets the wipe all ram. If you don't have a REX# or REX Classic, the next best option is to use a bootstrapper program on the modern machine that can install things onto the 100. On linux or mac, there is a good bootstrapper built in to dlplus. On Windows there is a powershell script called tsend. The other half of the equation is a tpdd server. LaddieAlpha is the best tpdd server for Windows. It also runs on linux and mac but needs some fiddling with mono to get running, but since you already needed dlplus for the bootstrapper, and dlplus is already a tpdd server, you can just use that. However Laddie supports TS-DOS subdirectories and dlplus doesn't yet. Each of these has their own directions. Now I'm just going to dump a bunch of links on you... (serial cable already linked above) http://tandy.wiki/TPDD_client (background, other tpdd clients besides ts-dos) http://tandy.wiki/TPDD_server (background, other tpdd servers besides laddie or dlplus) http://bitchin100.com/wiki/index.php?title=Rex (you want a REX#) https://github.com/bkw777/tsend (bootstrapper for windows) bitchin100.com/wiki/index.php?title=LaddieCon#LaddieAlpha (tpdd server for windows) https://github.com/bkw777/dlplus (bootstrapper and tpddserver for any unix-like, including linux & mac) There are a bunch of other options. For instance, the Backpack and PDDuino that was just recently discussed here. They are small hardware devices that emulate a TPDD drive and include bootstrappers to install TS-DOS or other tpdd clients onto the 100 pretty conveniently just like the actual TPDD2 had. If you have one of those, that's actually super convenient, but you can't buy a Backpack right now, and although you can build a PDDuino, it's a fair little project. https://www.youtube.com/watch?v=3es0NLJmd2c https://github.com/bkw777/PDDuino There is an Android app called mComm that is both a tpdd server and bootstrapper that runs on Android devices, but I think it has problems on the last few versions of Android. There is an older Windows version of mComm too, but I can't get it to work at all on current Windows10. There is a python version which works, at least on linux, but requires a little hacking to get it working and it doesn't include a bootstrapper. http://www.club100.org/memfiles/index.php?direction=&order=&directory=Kurt%20McCullum Most of the old DOS tpdd servers and bootstrappers are actually still usable today even from linux by using a dos emulator. In a couple of those links above I have some dosbox commandlines just to document the flags to make the serial port work. And of course there are several old articles that describe how to do a plain text transfer with the telcom app and hyperterm, but remember what I said about opinionated answers? My opinion is that is pointlessly difficult and limited and error-prone when we have better options, so that's why I didn't even mention that except to say "forget that" here. :) http://bitchin100.com/wiki/index.php?title=Text_File_Transfer_using_Hyperterminal > > 2. Aside from this mailing list, are there any other good Discord servers, > subreddits or forums that are active? I am already on the Slabtop Computer > Discord server, so looking any others. https://www.facebook.com/groups/Model.T.Computers Wouldn't be surprised about a subreddit but I don't know. > 3. Is there a new/different OS available for the Model 100? Do you have to > swap out the rom chip to do this? > > Thanks in advance! > Until very recently, no, but now, amazingly, yes. Revisit the REX link above, only this time you want REXCPM. You could also possibly stretch the definition to include mforth http://www.strangegizmo.com/products/mforth/ There was a thing called XOS which runs on the 200 not 100. Never used it but it looks like an interesting feat. https://github.com/LivingM100SIG/Living_M100SIG/blob/main/M100SIG/Lib-10-TANDY200/XOS-C.DOC http://www.club100.org/library/libpg.html -- bkw
