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Powertran Cortex

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    Count me in for one. At 15 euros it is a bearable risk, although I see the point about the money back guarantee if they're all duds.

    Paul

    Comment


      Yes, please, put me down for one as well.
      Is the Vendor somebody we've dealt with before ?

      Jim

      Comment


        Well it was through the same Chinese contact supplying the bits to the chap putting the 9900/9995 kits together who has been passing me some of his spares. But despite him (the Chinese contact) initially saying yes he could get them and his supplier guarantees quality, it has ended up that no he can't get them in either package type, the ceramic or the plastic.

        [My TMX9909 from eBay arrived in the post a while ago and seems to work fine. No Chinese supplier involved. ]

        Stuart.

        Comment


          Hi.

          Does anyone know where I can find a good quality set of Powertran Cortex schematics... someone may have already posted a link to them ?? I'm looking at reverse engineering some of the circuit.. It would be great if someone had already put some of the schematics into Eagle or some CAD system ? I can source the ICs reasonable cheap so it shouldn't cost too much .. ideally making a 'New' TMS9995 system for less than 100. This is still obviously in the 'Feasability' Stage.. but there's no reason why it should not be possible ?

          Best Regards
          Lez

          Comment


            Originally posted by lezanderson View Post
            Does anyone know where I can find a good quality set of Powertran Cortex schematics...
            http://www.powertrancortex.com/documentation.html

            Scroll down to:
            "ETI Construction Articles and Additional Hardware"

            Comment


              Working V9958 Video board...

              The memotech MTX forum has a working V9958 board with schematics:

              http://www.primrosebank.net/computer...txplus_vdp.htm

              OK .. it's for use with their Z80 system ... but could be configured for any homebrew microcomputer...worth a look anyway !

              Would look good wired up to a TMS9995 homebrew computer !

              Comment


                Following a very busy second half of 2014 it looks like I may have some time early in 2015 to resume my "ancient Unix on Cortex class hardware" project. First a quick stock take of where it is at:

                - Al Beard open sourced his C compiler for the geneve and it now lives on in the WHTech archive
                - The Ritchie C compiler was ported to the 9995 and works well enough to compile significant software
                - The 1983 edition of Xinu for the PDP-11 was ported and runs on Stuart's 9995 bread board
                - A Unix V6 user land runs on a 9995 emulator, with the OS calls handled by the emulator direct
                - Stuart's bread board was enhanced with a CF card interface
                - MDEX was ported to the enhanced bread board

                For reference see:
                The software repository
                The bread board schematics (warning: 4MB scan)
                A picture of the bread board
                A screen shot of MDEX running

                I'm pondering where to go next. The breadboard hardware could probably use simple memory mapping hardware, using the 7 spare lines of the LS259. I think with two more TTL chips I can create a design with 8 pages of 60KB each and the top 4KB always mapped to page 0. With the kernel running on page 0, that leaves room for 7 processes without swapping. I think this may work for porting the MDEX successor NOS as well, assuming that it has survived.

                On the software side, the LSX Unix kernel already compiles (but not sure if there are compiler bugs remaining). I'm a bit hesitant to debug that kernel on the real hardware, probably should try that on emulated hardware first. I have thought about adding write protect to the first and last 4KB, but I don't see a simple way to do it.

                Perhaps I should move the hardware to a PCB first. Jim, I noticed the MPE CPU-E manual on your site. The MPE E_BUS 9995 board looks like a nice start, and not a million miles away from what I ended up with on the breadboard. Do you have that MPE board? Perhaps a few hires photo's to have a baseline understanding of component placement and routing?

                The chip count of my breadboard design could probably be significantly reduced by using one or two GAL's, I noticed that Reichelt still stocks a 24 pin DIP GAL, but getting it programmed may be a hurdle that increases build complexity rather than reducing it; for sure I don't have a GAL programmer and have no GAL know-how.

                Also thinking ahead about building a small 99105 based system, to get the separate I/D address space and the supervisor/user modes, so that a process crashing doesn't bring down the whole system. Anybody working on/with 99105 based designs?

                All creative thoughts and support welcome.

                Comment


                  Originally posted by pnr View Post
                  Following a very busy second half of 2014 it looks like I may have some time early in 2015 to resume my "ancient Unix on Cortex class hardware" project. First a quick stock take of where it is at:

                  - Al Beard open sourced his C compiler for the geneve and it now lives on in the WHTech archive
                  - The Ritchie C compiler was ported to the 9995 and works well enough to compile significant software
                  - The 1983 edition of Xinu for the PDP-11 was ported and runs on Stuart's 9995 bread board
                  - A Unix V6 user land runs on a 9995 emulator, with the OS calls handled by the emulator direct
                  - Stuart's bread board was enhanced with a CF card interface
                  - MDEX was ported to the enhanced bread board

                  For reference see:
                  The software repository
                  The bread board schematics (warning: 4MB scan)
                  A picture of the bread board
                  A screen shot of MDEX running

                  I'm pondering where to go next. The breadboard hardware could probably use simple memory mapping hardware, using the 7 spare lines of the LS259. I think with two more TTL chips I can create a design with 8 pages of 60KB each and the top 4KB always mapped to page 0. With the kernel running on page 0, that leaves room for 7 processes without swapping. I think this may work for porting the MDEX successor NOS as well, assuming that it has survived.

                  On the software side, the LSX Unix kernel already compiles (but not sure if there are compiler bugs remaining). I'm a bit hesitant to debug that kernel on the real hardware, probably should try that on emulated hardware first. I have thought about adding write protect to the first and last 4KB, but I don't see a simple way to do it.

                  Perhaps I should move the hardware to a PCB first. Jim, I noticed the MPE CPU-E manual on your site. The MPE E_BUS 9995 board looks like a nice start, and not a million miles away from what I ended up with on the breadboard. Do you have that MPE board? Perhaps a few hires photo's to have a baseline understanding of component placement and routing?

                  The chip count of my breadboard design could probably be significantly reduced by using one or two GAL's, I noticed that Reichelt still stocks a 24 pin DIP GAL, but getting it programmed may be a hurdle that increases build complexity rather than reducing it; for sure I don't have a GAL programmer and have no GAL know-how.

                  Also thinking ahead about building a small 99105 based system, to get the separate I/D address space and the supervisor/user modes, so that a process crashing doesn't bring down the whole system. Anybody working on/with 99105 based designs?

                  All creative thoughts and support welcome.
                  Good to hear from you Paul!

                  I have one unread email in my gmail inbox. It's from you in April concerning the c compiler port for the Cortex. It's been one of those years and not sure it's easing up in 2015. I will get to it eventually I hope!

                  I do have a fantasy about getting my emulator running on a Raspberry Pi and creating an E-Bus interface for it via the SPI interface. It's good to dream...

                  Dave.

                  Comment


                    Greetings, and Happy New Year to one and all. My resolution for this year is to understand what one can actually do with all this stuff that Paul has been doing.

                    I got an e-mail yesterday from a chap called Alex Cameron in Australia who has set up a website for stuff he done 25 years ago ... including a TMS99105 SBC. Details, including schematics, on his website: http://www.itech.net.au/tms9900.

                    I think Jim H was working on a TMS99105 design as well, but I think the PCB for that is currently around 6 feet square from all the features he was trying to include.

                    Stuart.

                    Comment


                      Thanks for the info!

                      I noticed that photo's of the MPE CPU board are already posted in message #462 of this thread. I think I might try my hand at the ExpressPCB schematics and layout software over the coming months.

                      Currently busy finalising the LSX Unix port (on the breadboard simulator) -- good progress, it might actually run during the course of this week. Considering the experience built up with the XINU and MDEX ports, moving to the real hardware should not be a stretch. Porting to a real Cortex should also be straightforward from there.

                      Comment


                        Gentlemen,

                        I'm happy to report that LSX Unix now runs on the breadboard simulator. Next step is the real hardware. Attached is a screenshot of a sample run.

                        In essence the LSX kernel runs in the first 16 kB, and the other ram is available for user programs. A user program calls into the kernel via a XOP 1 instruction. There is always only one program in memory and the other processes are swapped out to disk. There are 3 processes max.

                        This memo http://www.60bits.net/msu/mycomp/terak/termubel.htm by Hans Lycklama (the guy who cut down Unix version 6 to the LSX and Mini versions back in the mid 70's) describes the capabilities versus Unix version 6. The little kernel is less performant, but runs most userland programs unchanged.

                        My current compilation does not quite fit in 16 kB, it needs about 17kB. Perhaps I need to do more work on the compiler's optimiser, perhaps the code density of the 990 is just a bit less. Note that this sizes are inclusive of data areas and buffers, the actual kernel code is only 11 kB.

                        Paul

                        And here is a link for a proper screenshot
                        Attached Files
                        Last edited by pnr; January 14, 2015, 12:22 PM.

                        Comment


                          Nice work! We could probably port this over to a Geneve 9640 too--it uses a memory mapper to give it access to up to 2M of memory on a 9995-based machine.
                          Enter My Mind At Your Own Risk!

                          Comment


                            Originally posted by Ksarul View Post
                            Nice work! We could probably port this over to a Geneve 9640 too--it uses a memory mapper to give it access to up to 2M of memory on a 9995-based machine.
                            Yes, that would be a cool project. If you know the Geneve 9640 hardware and its drivers well, it should be an easy project to do. Lot's of overlap with the Cortex that also uses a '612 mapper chip. Let me know if you need any pointers on how to get started with the code.

                            Actually, my build of Stuart's breadboard has a 512KB RAM chip and I think it would not be very hard to make a version of LSX that keeps 7 processes in mapped RAM, with the 8th slot for the kernel. Note that adding mapped memory makes for a fairly straightforward road from LSX, via Mini to full V6:
                            - LSX was designed to run with 40KB RAM and two 256KB floppies (kernel 10KB, ~3.600 sloc)
                            - Mini was designed to run with 56KB RAM and 5MB harddisk (kernel 18KB, ~6.500 sloc)
                            - V6 was designed to run with 256KB RAM and 5...40MB harddisk (kernel 28KB, ~10.000 sloc)
                            All versions can use essentially the same set of userland programs.

                            Comment


                              Where did you find the LSX source code? All I can find are binaries.
                              I use my C128 because I am an ornery, stubborn, retro grouch. -- Bob Masse
                              Various projects and oddities: http://oldvcr.blogspot.com/
                              Machine room: http://www.floodgap.com/etc/machines.html

                              Comment


                                Originally posted by ClassicHasClass View Post
                                Where did you find the LSX source code? All I can find are binaries.
                                The original source files are in the Unix Tree at the The Unix Heritage Society:
                                http://minnie.tuhs.org/cgi-bin/utree.pl
                                or more specifically:
                                http://minnie.tuhs.org/cgi-bin/utree.pl?file=LSX

                                Leonid Broukhis did a lot of work making the stuff usable for the BKUNIX project. This you find here:
                                http://sourceforge.net/p/bkunix/code/HEAD/tree/trunk/

                                My repo with the port from the PDP-11 to the 9995 is here:
                                http://1587660.websites.xs4all.nl/cg...doc/index.wiki
                                Note that the cover page is a bit out of date.

                                Comment

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