Manic1975 Posted October 9, 2014 Share Posted October 9, 2014 Have someone try to build his own PEB? Have someone rebuild PEB mainboard? Quote Link to comment Share on other sites More sharing options...
gregallenwarner Posted October 9, 2014 Share Posted October 9, 2014 The "mainboard" in the PEB is really just a backplane--that is, just a bunch of parallel traces to connect all the busses together. Even standard ATX power supplies can be used to power the PEB. The only real critical part of the PEB is the flex cable and interface card. With a suitable power supply, the flex cable interface card, and connectivity between cards, there's no reason why you couldn't build your own PEB. It would just be a lot of work, and you wouldn't have the nice cutouts and slots to hold all your cards neatly in place. I believe I remember seeing somewhere some photos where a user built a PEB into an ATX PC case. They probably took the backplane out of the PEB and mounted it somehow in the PC case. So I know it's possible. 1 Quote Link to comment Share on other sites More sharing options...
+mizapf Posted October 9, 2014 Share Posted October 9, 2014 The problem, as I remember, is that PEB cards all have their own voltage regulators, so that simply using an ATX power supply won't work. People replacing their PEB power supply with a standard power supply report to have removed those regulators from their cards. Quote Link to comment Share on other sites More sharing options...
gregallenwarner Posted October 9, 2014 Share Posted October 9, 2014 I believe you can get away with it by hooking your ATX 12 volt rail directly to the PEB 8 volt rail, if all your cards have proper heatsinking. Of course, 12 volts on the 15 volt rail isn't good if your cards that require a 7812 regulator can't handle the voltage drop incurred by insufficient headroom. Removing the regulators on all your cards is the safest way, though time consuming. Plus, those cards will no longer work in an unmodified PEB! Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted October 9, 2014 Share Posted October 9, 2014 (edited) I believe you can get away with it by hooking your ATX 12 volt rail directly to the PEB 8 volt rail, if all your cards have proper heatsinking. Of course, 12 volts on the 15 volt rail isn't good if your cards that require a 7812 regulator can't handle the voltage drop incurred by insufficient headroom. Removing the regulators on all your cards is the safest way, though time consuming. Plus, those cards will no longer work in an unmodified PEB! I have been tinkering with the power supply in the PEB. I found some DC-DC converters which could supply 18V for the 16V rail using 12V (150% increase, maximum recommended) as the supply, but it cannot be a "cheap" low-power PSU: needed at minimum amperage rating that I cannot recall off the top of my head. The short is that it would not be possible to just hook up an AT or ATX supply without some kind of conversion interface. One day over the rainbow I might actually build the damned thing Edited October 9, 2014 by OLD CS1 Quote Link to comment Share on other sites More sharing options...
+InsaneMultitasker Posted October 9, 2014 Share Posted October 9, 2014 I would argue that removing the regulators is not safer or preferred. If you install a modified card in an unmodified PEB, the card will not survive. Secondly, removing the regulators reduces isolation between cards. Having repaired a number of cards with the regulators removed, I do not recommend this approach. The 12 volt regulators will function adequately for the cards that require them when supplied by 12v or -12v. The "usual" practice has been to connect +12 to +12, -12 to -12, and +12 to +5. The regulators must be properly heat-sinked. (For the record, my system runs 24x7 in this configuration with no issues. I believe others on this forum have done the same.) 2 Quote Link to comment Share on other sites More sharing options...
Gazoo Posted October 9, 2014 Share Posted October 9, 2014 I would argue that removing the regulators is not safer or preferred. If you install a modified card in an unmodified PEB, the card will not survive. Secondly, removing the regulators reduces isolation between cards. Having repaired a number of cards with the regulators removed, I do not recommend this approach. The 12 volt regulators will function adequately for the cards that require them when supplied by 12v or -12v. The "usual" practice has been to connect +12 to +12, -12 to -12, and +12 to +5. The regulators must be properly heat-sinked. (For the record, my system runs 24x7 in this configuration with no issues. I believe others on this forum have done the same.) I'll second Old InsaneOne's approach. Both my TI & Geneve have been running off PC power supplies for about 20 years now. They've gone through a couple of different cases each, when I needed to change configs. I like the current cases I have though, AT cases are better suited than ATX cases, so Ebay is the best option to find new old stock for that sort of thing. Gazoo TI Inside Geneve Inside 1 Quote Link to comment Share on other sites More sharing options...
Gary from OPA Posted October 9, 2014 Share Posted October 9, 2014 Have someone try to build his own PEB? Have someone rebuild PEB mainboard? The biggest problem I hate with PEB is the weird non-standard voltages, having a new PEB using a standard switching power supply would be the bomb, but then all the cards would need to be jumper to not use their voltage regulators. The other thing is the real estate, the cards are so big, but then designing a mini-peb would mean all new cards also, and of course it would be great if PEB was 16bit, with direct 16bit access to the console instead of the slow 8 bit interface. Quote Link to comment Share on other sites More sharing options...
Gazoo Posted October 10, 2014 Share Posted October 10, 2014 The biggest problem I hate with PEB is the weird non-standard voltages, having a new PEB using a standard switching power supply would be the bomb, but then all the cards would need to be jumper to not use their voltage regulators. No! No jumpers! Please read the last 2 messages. Gazoo Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted October 10, 2014 Share Posted October 10, 2014 Well, then. Screw the DC-DC converters What amp ratings are your 12V rails on the ATX PSU? Quote Link to comment Share on other sites More sharing options...
Gazoo Posted October 10, 2014 Share Posted October 10, 2014 Well, then. Screw the DC-DC converters What amp ratings are your 12V rails on the ATX PSU? Unless you're putting a full height powersucking MFM drive in the case, a 250 watt power supply should be fine (don't know how to relate that to amps). I've got a 300 watt power supply in my Geneve case, and I use a separate 12v Power supply (Home Alarm) to power the MFM drive (Imprimus) just to be safe. Gazoo Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted October 10, 2014 Share Posted October 10, 2014 Why does the PEB not have or require termination? Quote Link to comment Share on other sites More sharing options...
gregallenwarner Posted October 10, 2014 Share Posted October 10, 2014 My guess is the rediculously slow bus speeds. Termination is only required to prevent signal reflections from corrupting data on the line. With the TI's already slow clock speed of 3 MHz, with the added wait states, there's an eternity of time for any reflections to subside before anything starts sampling data. Quote Link to comment Share on other sites More sharing options...
Gary from OPA Posted October 10, 2014 Share Posted October 10, 2014 My guess is the rediculously slow bus speeds. Termination is only required to prevent signal reflections from corrupting data on the line. With the TI's already slow clock speed of 3 MHz, with the added wait states, there's an eternity of time for any reflections to subside before anything starts sampling data. Almost all PEB's cards use a series of chips like the 244 and 245 on each card to make the bus terminated and stronger to push/pull data. Plus the big heavy fire hose FLEX card for the PEB from the TI99 to the cage, is the one doing all the work in making the backplane what it is. A replacement PEB should also include a new FLEX card for those not using a GENEVE or AVPC2 cards. -- This was done once before by RyteData they produced a 5 slot PEB card that you could mount in old Turbo XT desktop case, that included a flex card onboard that could be enabled if not using a Geneve, and they jumped the voltage reguators on the cards to use the normal PC AT power supply. Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted October 10, 2014 Share Posted October 10, 2014 I have one of those RyteData boards. . .they are an interesting bit of hardware. Rave also produced a new PEB of their own--I think there are something like 100 or so of them out there. I have one of those as well. 1 Quote Link to comment Share on other sites More sharing options...
gregallenwarner Posted October 13, 2014 Share Posted October 13, 2014 Time for another update: Sorry it's taking so long. I just finished spending a lot of time optimizing and improving the PCB layout. Some of the new additions I made: * Simplified the power supply circuitry to reduce part count and improve reliability. * Added test points for voltage regulators. * Added input fuses on the PEB power rails to provide fault tolerance. * Ditched the tantalum caps for more reliable aluminum electrolytic ones. * Added dedicated header for optional LED--no soldering required. LED will be provided upon request. * Optimized a few traces for better routing, fewer vias, and better ground plane coverage. * Board now decodes AMA thru AME, with AMD and AME being optionally selected by a solder bridge. (Close solder bridge if you are running GenMod.) I think I might actually be finally done with the design! I find that I'm very nit-picky about my PCB designs. I want everything to be perfect. But I believe this is in a state where I can call it finished! This is most likely the version that will go out to the people who indicated their interest. Rendered preview attached. 8 Quote Link to comment Share on other sites More sharing options...
Asmusr Posted October 13, 2014 Share Posted October 13, 2014 Excellent, my PEB will love this! 1 Quote Link to comment Share on other sites More sharing options...
Iwantgames:) Posted October 21, 2014 Share Posted October 21, 2014 Any news on how this project is progressing? Quote Link to comment Share on other sites More sharing options...
gregallenwarner Posted October 21, 2014 Share Posted October 21, 2014 (edited) I've done some initial testing with the prototype I built, and I was able to successfully get the speech synth to work under TE2, however, the synth was inoperable in XB using CALL SAY. This leads me to believe that the TI is having difficulty reading from the SS. It can write to it just fine, but when it attempts to read the contents of the SS's vocab ROM, that's where it's failing. I've got a couple of different debugging avenues to check, and I mailed the prototype to Ksarul, who is going to take a look at it this weekend, so we're attacking this problem on two fronts. I also have a couple of different PCB designs already mocked up for when the problem is identified, if in fact the problem is what I think it is. I thank you all for your patience while I figure out all the details. This is my first project that I'm actually going to sell, so my OCD is running in overdrive right now, making sure that the adapter card is perfect. Edited October 21, 2014 by gregallenwarner 1 Quote Link to comment Share on other sites More sharing options...
+mizapf Posted October 21, 2014 Share Posted October 21, 2014 I suppose Parsec and other cartridges work as well, while CALL SPGET also fails? Quote Link to comment Share on other sites More sharing options...
Fritz442 Posted October 21, 2014 Share Posted October 21, 2014 I've done some initial testing with the prototype I built, and I was able to successfully get the speech synth to work under TE2, however, the synth was inoperable in XB using CALL SAY. This leads me to believe that the TI is having difficulty reading from the SS. It can write to it just fine, but when it attempts to read the contents of the SS's vocab ROM, that's where it's failing. I've got a couple of different debugging avenues to check, and I mailed the prototype to Ksarul, who is going to take a look at it this weekend, so we're attacking this problem on two fronts. I also have a couple of different PCB designs already mocked up for when the problem is identified, if in fact the problem is what I think it is. I thank you all for your patience while I figure out all the details. This is my first project that I'm actually going to sell, so my OCD is running in overdrive right now, making sure that the adapter card is perfect. NP on waiting, no hurry here Please take your time and get everything as you want it. 1 Quote Link to comment Share on other sites More sharing options...
Omega-TI Posted October 21, 2014 Author Share Posted October 21, 2014 NP on waiting, no hurry here Please take your time and get everything as you want it. This is a good sign in my book. While I've always been a fan of instant gratification, everyone now knows that this will be a QUALITY piece of equipment, because he's taking the time and effort to DO IT RIGHT. Quote Link to comment Share on other sites More sharing options...
gregallenwarner Posted October 21, 2014 Share Posted October 21, 2014 I suppose Parsec and other cartridges work as well, while CALL SPGET also fails? While I haven't checked either of those specifically, my intuition tells me that that is correct. Those will be among my further tests, once I assemble a 2nd prototype for myself, but I am also going to write an assembly program to try and read the speech ROMS as well, and run it both with the adapter card and also with the SS directly plugged into the side, and compare the results. Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted October 21, 2014 Share Posted October 21, 2014 Well worth the wait, so far as I am concerned. Plus, your toil could benefit others who want to do similar projects in the future. Quote Link to comment Share on other sites More sharing options...
gregallenwarner Posted October 21, 2014 Share Posted October 21, 2014 I'm definitely learning a lot about how the TI works, that's for sure! 2 Quote Link to comment Share on other sites More sharing options...
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