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Powertran Cortex

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    Hello,

    It seems I have the same delay as other newcomers, before my messages arrive on the board. So we have to communicate with a time shift.

    Originally posted by Stuart View Post
    Hi Dexter. I haven't yet (personally) seen any genuine (I think) TMS99xx chips without (1) a clear 4-digit date code for the 80's or 90's and (2) a correct part number. So those you have would seem a little suspect to me due to no 4-digit date code. Having said that though, I've got a couple of Chinese clone chips and they all seem to work ...
    So there might still be a chance that they work.

    I already build two single board computers, MARC-1 and MARC-2, based on 6502 and 65816. MARC-3 also would have been 65816 based, but modular, with a back plane and sort of an S-100 bus. I already build the back plane, but changed the design of the cards to match it to the TMS9995.

    The first card will contain the TMS9995 CPU and a XC95108 CPLD. All lines of the CPU are on the expansion connector and on the CPLD. The rest of the CPLD I/O lines are connected to the expansion port. This way I can add more complexety to my computer as I go.

    The second card will contain a 512KiB 55ns Aliance SRAM with an ATMega1284P connected to all lines of the SRAM. This way I can copy the firmware into the SRAM during RESET. Developing new software will also be very quick.

    The third card will have some I/O like the F18A, SN76489 (TI99 sound chip) and my favorite DUART SC26C92.

    While learning and programming on the TI-99/4A, I enjoyed the 9900 assembly language so much, that I wanted it on my home build computer. Your site gave me the last push to change from the 65816 to the 9995, because it had the schematic I need.

    Originally posted by pnr View Post
    It is not modular, but I'm doing a eurocard version of the Cortex (keep reading the thread, it shows up at page 78 or so). I can send you a bare PCB if that is any help (or the design files if that is what you need).
    Thanks for the offer, but I hope I wonít need a PCB. I did get a schematic from you on the AA forum, ďMini Cortex TI990/6 Rev. 1.0 2/23/2015Ē. However, more info / schematics are certainly welcome. Iím eager to study them.



    Originally posted by pnr View Post
    Alternatively, Stuart's breadboard is a great way to get going and test parts: just wire up the 9995 and a ROM, run the test routines and a logic tester or scope will tell you if the part is working or not.
    Thatís probably the fastest way to get those 9995ís tested. Iíll set this up these days and report weather theyíre working or not. Which test routines are you referring to? I could program something myself, and wiggle some address lines, but if there is some test program for just the CPU and ROM.


    Originally posted by pnr View Post
    I have no personal experience with UTSource but I have read mixed opinions about them. My TMS9995's come from G&C superstore. These parts look like NOS, although I suspect they are very nicely refurbished pulls.
    UTSource never disappointed me, this would be the first time. At least itís good to know an alternative source for these parts, if the ones I have donít work.

    Originally posted by pnr View Post
    The TMS9995 is a very nice part. Without wait-states it runs about as fast as a PDP11/40.
    Yes, Iím very excited to see my computer run with this CPU, I hope it will run on 16Mhz eventually.

    Comment


      I read the whole thread. Phew!

      Meanwhile, I wrote a little test program to toggle the 9th and 10th address lines, put the 9995 with the program on EPROM on breadboard, and could confirm that CLKOUT puts out 1/4 of the clock signal. After a reset, the address lines toggled happy on my old scope.

      I tried 4, 8, 12 and 16MHz crystals successfully.

      So it seems the CPU's are working. But I'm still not sure about quality and durability.
      If there is someone here who would want to part one or two TMS9995NL's, I'd be more confident. The two sources mentioned in this thread aren't available anymore.

      Comment


        Somewhere in the first half of 2014 someone (might have been Jim Hearne) posted a link, or otherwise put me in the direction of a 99000 series design handbook (I don't mean the datasheet). I cannot find that link or reference anymore, nor can I find it on my drive. Does this ring a bell with anyone?

        Comment


          Originally posted by pnr View Post
          Somewhere in the first half of 2014 someone (might have been Jim Hearne) posted a link, or otherwise put me in the direction of a 99000 series design handbook (I don't mean the datasheet). I cannot find that link or reference anymore, nor can I find it on my drive. Does this ring a bell with anyone?
          This TI Designers Handbook has a TMS99000 section in it:

          http://www.quantums.info/cortex/TI%2...%20edition.pdf

          Hopefully it's what you were thinking of?

          Comment


            Or one of the first two listed here?

            http://www.avjd51.dsl.pipex.com/tms9...htm#references

            Comment


              That's it! It was the "Architecture Software and Interface Techniques" book that I was looking for. Many thanks both!

              Comment


                Originally posted by Dexter View Post
                Thanks for the offer, but I hope I wonít need a PCB. I did get a schematic from you on the AA forum, ďMini Cortex TI990/6 Rev. 1.0 2/23/2015Ē. However, more info / schematics are certainly welcome. Iím eager to study them.
                The schematics changed slightly after that, and I'm contemplating some further changes for a second revision of the PCB. Your proposed system sounds very interesting! What do you plan for mass storage?

                Originally posted by Dexter View Post
                So it seems the CPU's are working. But I'm still not sure about quality and durability. If there is someone here who would want to part one or two TMS9995NL's, I'd be more confident. The two sources mentioned in this thread aren't available anymore.
                Good to hear your two parts are fine and can even be clocked at 16MHz. Not sure what you mean by sources "not being available anymore": I just now typed in "tms9995" into the ebay search box and got 27 listings, including all the suppliers mentioned in this thread.

                Comment


                  Originally posted by pnr View Post
                  Your proposed system sounds very interesting! What do you plan for mass storage?
                  On MARC-3 Iíll have a hardware based SPI controller for eight devices. So one of those devices is an SPI to IDE CF adapter, another will be a Real Time Clock with temperature sensor. SPI is pretty common, and with this hardware SPI controller, itís as fast as I can write bytes to a memory address.

                  IDE adapter
                  http://sbc.rictor.org/ide.html

                  65SPI
                  http://sbc.rictor.org/65spi.html


                  Originally posted by pnr View Post
                  I just now typed in "tms9995" into the ebay search box and got 27 listings, including all the suppliers mentioned in this thread.
                  Never mind, youíre right, I must have typed something odd while searching for that vendor.

                  Comment


                    I'm happy to report that Dave Pitts has ported Unix for the 9995 to the TI990 mini's (990/5, 990/10 & 990/10A), both in simulation and on "real" hardware. He has also greatly improved and cleaned up the build system (i.e. the makefiles). His contributions have been added to the code repo.

                    Comment


                      Originally posted by pnr View Post
                      I'm happy to report that Dave Pitts has ported Unix for the 9995 to the TI990 mini's (990/5, 990/10 & 990/10A), both in simulation and on "real" hardware. He has also greatly improved and cleaned up the build system (i.e. the makefiles). His contributions have been added to the code repo.
                      Any idea how the TI990 minis compare speedwise with the 9995 with no wait states?

                      Comment


                        Originally posted by Dexter View Post
                        Hello everyone, I'm Dexter from the AA forum. I've been reading this thread for a few days now, I'm at post #659 page 66. Some amazing stuff you've done, despite the Cortex is so rare. I'm interested in building a TMS9995 modular homebrew computer.

                        I ordered two TMS9995NL, two TMS9902NL and a few SN76489AN from UTSource. The TMS9995NL are most likely pulls, they are a bit scuffed / scratched, what I interpret as a good thing. On the other hand, they could be counterfeits, perhaps someone of you can determine?
                        Hi.

                        I sent some TMS99xx ICs from China to Stuart , I believe he found a few DUFF ones but on the whole they seemed to work. Stuart should be able to enlighten you more on that.

                        I sourced them from Funkward-tech and G&C Supermarket...the G&C ones looked brand new (which they probably were not ) the Funkward-Tech ones where clearly Pulls. God knows where they came from originaly.. I can only assume scrap boards ??

                        I did get free replacements for the DUFF ICs

                        Comment


                          Originally posted by Stuart View Post
                          Any idea how the TI990 minis compare speedwise with the 9995 with no wait states?
                          Only a vague idea I'm afraid.

                          The TI990/5 is based on the 9900 chip, running at 3MHz. It has on 64KB on board DRAM that should be able to keep up with the CPU without wait states. I guess that makes it run at about half the speed of a 9995 without wait states.

                          The TI990/10A is based on a 99000 chip, I'm not sure which type. It would seem logical for to be the 99110, but the the LDS and LDS instructions seem to be slightly different and the documentation always refers to the CPU as the TMS99000, so it may be a special (however, Karl Guttag does not recall such a special version). The CPU on Dave's board has no markings left, so it remains a bit of an enigma. In any case, speed will be 99105/110 like. I think it runs at 6MHz with wait states, as the 256KB of on board DRAM (1981 era) would probably go no faster than 300-400ns access time. So, perhaps the 10A is a little faster than a 9995 without wait states.

                          The TI990/10 is an implementation with discrete TTL chips, and the 990/10A manual says it is about 70% faster than a 990/10 on CPU bound code. Memory is accessed via the TILINE bus, which probably means access times of around 500ns. So I think that the 990/10 will probably be a bit slower than a 9995 without wait states.

                          Dave's DS50 hard drive is currently not working, so he ran the code of a DSDD 8" floppy. This will make the system a lot slower, swapping processes on and off disk perhaps takes up to a few seconds.

                          Comment


                            Originally posted by lezanderson View Post
                            Hi.

                            I sent some TMS99xx ICs from China to Stuart , I believe he found a few DUFF ones but on the whole they seemed to work. Stuart should be able to enlighten you more on that.

                            I sourced them from Funkward-tech and G&C Supermarket...the G&C ones looked brand new (which they probably were not ) the Funkward-Tech ones where clearly Pulls. God knows where they came from originaly.. I can only assume scrap boards ??

                            I did get free replacements for the DUFF ICs
                            Sorry, I just now noticed your replay. Actually Stuart did on post 854, nevertheless, they *seem* to work, but I can tell for sure when I have a running computer.

                            It can take a while though until I have something build, because of my health. But I will build it for sure.

                            Comment


                              First of all best wishes for the New Year!

                              I am happy to report that over the holidays I've completed the port of Version 6 Unix to the Powertran Cortex, the mini-Cortex to be exact. It turns out to be about 22KB of code and 18KB of data (mostly disk buffers), for a total of 40KB. It feels a little more responsive than the smaller LSX kernel as it does not have to swap to disk. Also, the tool chain (C compiler, etc.) now runs natively: the system can compile itself from source on the mini-Cortex hardware. I have finally proven to myself that Cortex class hardware was powerful enough to run early Unix. The difference between mini computers and TI home computers was not in the CPU, but in the amount of RAM and in the hard disk.

                              I also now know that my project from back in the day (a modified TI99/4A with 32KB in-console RAM and a homebrew DSDD floppy) would have needed further modification to run it: one needs 64KB of RAM at least, 128KB preferable. This would have required a board with dynamic RAMs which would have been hard to fit into the console. Also, at the time I had access to the source code for the kernel (the Lion's book), but not to the source of all the other (user) programs. Recreating this would have been a major challenge.

                              Dave Pitts has ported the LSX kernel to the TI990 mini's, as reported before. He has also since rewritten the assembly bits to use his own tool chain (a modified gcc compiler and his own assembler and linker, which we also use for recreating the Cortex Basic ROM). His version of GCC generates code that is about the same size as my version of the Ritchie compiler. Both compilers have different approaches to register and stack handling, and I think there is no obvious way to generate even more compact code.

                              My hobby goal for 2016 is to round out and document:
                              - A new version of the mini Cortex, incorporating lessons learned in the past year
                              - A nice website that makes it easy for others to take what is there and take it in new directions (for example a port to the Geneve)
                              - More user programs
                              - A new boot ROM

                              Time permitting I hope to play with Dave's upcoming Cortex port of NOS and -- with other Dave's input -- with running TI990 mini software on the Cortex.

                              Happy hacking in 2016!
                              Last edited by pnr; January 8, 2016, 10:50 AM.

                              Comment


                                Nice. Do you have an image of UNIX V6?
                                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

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