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MrTransistor

Project Announcement - PEB

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Hello everyone. I am Mister Transistor.

 

I would like to share with you a project that I have been developing.

 

It is not a nano-peb type of device, and my goal is to allow existing expansion cards in a modern peripheral box.

 

I have the boards designed and played out, and I am still tweaking the power supply design. After this I will be moving on to systems design, i.e. arranging it in a chassis and prototyping.

 

The whole reason I am writing this is to gauge interest in a device like this, and whether or not I will make more than one.

 

Further, if there is interest, I would love to hear about your thoughts on improving the design of the original PEB, such as the cable interface being awkward and bulky sticking out of the side of the console. (this is not a problem with my design however, but just an example.)

 

So far, I have a few things that I have decided on. First, miniaturization of the boards. To accomplish this and still retain backwards compatibility with existing cards, I have decided on a modular expansion slot board, where there are 3 per module, and this allows for a smaller box, or expansion of the existing box if so desired. Of course, expansion would require a beefier power supply, so there's that too. This can also be made smaller by sacrificing slots.

 

I will be making at least one, for my own use, but I am willing and capable of manufacturing more if requested. Please let me know what you think, and if you have any specific questions or input, please don't hesitate to ask.

 

Thanks!

 

Your friendly neighborhood CSE

 

 

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Posted (edited)

I guess it would depend, as I see it, on what type of expansion cards can be had.

If it gives the existing TI console a better video card and programmable Roms that can overide the internal Roms or Allow multi boot while keeping the existing 9900 or compatible cpu It be great!

I guess I'd have to see more of what you're talking about. But welcome, and congratulations on a new idea!!!

Edited by GDMike

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This is interesting, want to know more.

For me it´s important that the Geneve card fits.

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I guess it would depend, as I see it, on what type of expansion cards can be had.
If it gives the existing TI console a better video card and programmable Roms that can overide the internal Roms or Allow multi boot while keeping the existing 9900 or compatible cpu It be great!
I guess I'd have to see more of what you're talking about. But welcome, and congratulations on a new idea!!!
Mike. You are asking for cards that work in a expansion system that don't exist. This is just the slots and power supply.

Sent from my LM-G820 using Tapatalk

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What is meant by modular expansion slot?  Are you talking 2 distinct kinds of connectable mini-expansion-boxes?  1 compatible with legacy cards, 1 compatible with the new 'miniaturized' form factor cards... 

 

If the flex cable problem is solved, what is it replaced with? What kind of physical form factor are you talking about --- actual metrics would be interesting. I'd like to see some design photos / screen captures from your cad tools, so we can get a visual idea of what you are talking about. How does it sit on a desk amongst a 4A? Can an old PEB still be attached?

 

For the module that is compatible with old cards, are the cards required to have their onboard regulators adjusted? Or will the powersupply be at the same higher voltages that the legacy PEB produces? Does the PSU require a fan? Is the transformer built into the system, or is it a DC-to-DC style PSU with a external transformer brick? 

 

A bunch of people have side-port TIPI or 32K or SAMS cards that have a sideways PI-Hat style expansion capability... When people talk about building new things of this nature ( http://www.mainbyte.com/ti99/hardware/9900_micro/9900_micro.html ) I often think the sideways PI-HAT would be more viable if the boards were bigger, and not sideways.. so they stacked. 

 

Is there plans to open source your designs?, so that if you build a 3 board box, someone an build a 5 board box... Or a module for my sideport style boards... 

 

What's a CSE? Canadian Securities Exchange? 

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There was (and probably still is) a cable extension for the PEB that move the "foot" out of the way if that is your major concern.

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It is very interesting for me too. 
waiting for a TIPI board that can read real Floppy disks and tapes and save on SD card, i would be happy to have a Slimmer PEB 😛 

A better optimized method to interface cable it to the TI-99/4A could be nice also, yes.
 

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It is very interesting for me too. 
waiting for a TIPI board that can read real Floppy disks and tapes and save on SD card, i would be happy to have a Slimmer PEB  
A better optimized method to interface cable it to the TI-99/4A could be nice also, yes.
 
You mean a disk controller not a TIPI. You can then read from a disk or tape and save on TIPI's sd.



Sent from my LM-G820 using Tapatalk

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2 hours ago, arcadeshopper said:

Cool got any pictures of the boards or prototype?

Sent from my LM-G820 using Tapatalk
 

I haven't produced the gerbers yet, and prototyping is a little bit off from here. I'm still hammering out the fine details for things like the power supply, evaluating my options, etc.

 

I will probably make a mockup at some point, either in small scale or in a 3d model version. I will update you when this is available. 

2 hours ago, GDMike said:

I guess it would depend, as I see it, on what type of expansion cards can be had.

If it gives the existing TI console a better video card and programmable Roms that can overide the internal Roms or Allow multi boot while keeping the existing 9900 or compatible cpu It be great!

I guess I'd have to see more of what you're talking about. But welcome, and congratulations on a new idea!!!

This is simply an expansion box, like the original PEB. The compatibility requirements will include all standard PEB cards, and I will look into any specific cases that may not be, and I will include compatibility for these as well.

2 hours ago, Nick99 said:

This is interesting, want to know more.

For me it´s important that the Geneve card fits.

I will make sure that they will be included.

2 hours ago, jedimatt42 said:

What is meant by modular expansion slot?  Are you talking 2 distinct kinds of connectable mini-expansion-boxes?  1 compatible with legacy cards, 1 compatible with the new 'miniaturized' form factor cards... 

 

If the flex cable problem is solved, what is it replaced with? What kind of physical form factor are you talking about --- actual metrics would be interesting. I'd like to see some design photos / screen captures from your cad tools, so we can get a visual idea of what you are talking about. How does it sit on a desk amongst a 4A? Can an old PEB still be attached?

 

For the module that is compatible with old cards, are the cards required to have their onboard regulators adjusted? Or will the powersupply be at the same higher voltages that the legacy PEB produces? Does the PSU require a fan? Is the transformer built into the system, or is it a DC-to-DC style PSU with a external transformer brick? 

 

A bunch of people have side-port TIPI or 32K or SAMS cards that have a sideways PI-Hat style expansion capability... When people talk about building new things of this nature ( http://www.mainbyte.com/ti99/hardware/9900_micro/9900_micro.html ) I often think the sideways PI-HAT would be more viable if the boards were bigger, and not sideways.. so they stacked. 

 

Is there plans to open source your designs?, so that if you build a 3 board box, someone an build a 5 board box... Or a module for my sideport style boards... 

 

What's a CSE? Canadian Securities Exchange? 

Computer Science and Engineering. CSE. Lmao, kind of an uncommon major, but it's growing. It's a mix between computer science and electrical engineering.

 

As to your other questions, the modular design is to make it possible to have a smaller box, with the opportunity to expand on this and put more cards in. These will be really cheap, though, because they're just the slots, board, and board-to-board connectors. 

 

Unfortunately, I don't have any images right now, but I am going to start making some mockups today, and that's all part of the systems design portion that i'm about ready to move on to. 

 

The power supply will be directly compatible with the voltages required for the cards. Again, if there are specific needs, I can add some sort of adapter or something that will bring the voltage where it needs to be. The plan is to have complete compatibility with the original PEB.

 

 

Sideport boards were something I was planning on adding an adapter for, like a pass-through for the sidecar port or something, but that is just a thought right now, because it would probably complicate the design a bit, and possibly make it a little bigger than I would like. Otherwise, i'd probably just slap a sideport on the back or something like that, but I don't really know at this point. 

 

For the sideport interface, it's an internal board which will replace the interface board in the cable of the PEB.  Think a flex cable with a standard slot on the end, if you want to picture what i'm picturing.

 

As for the details like fans and stuff for the power supply, I will likely include a brushless fan or something, maybe a thermal cutout to protect the temperature sensitive components. The power supply design is likely going to be linear, to reduce noise and lower the part count for filters, thus reducing cost. This introduces the problem of heat, which could be remedied by a fan and some good heatsinks, but this is a detail I haven't settled on quite yet.

 

As for open source hardware, that is very likely. I'll just have to clean up the schematics and make up some documents to guide development and expansion, in that case.

 

 

I will update with pictures soon. Thanks everyone!

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I am interested.

 

If the case can be "off the shelf readily available", then weight of the guts for the internals should be a high priority.  This will minimize shipping costs, especially to international customers where they can pick up a case overseas that would work and would just need some slip-in internals.

 

Nobody has spoke of it yet, but the unit needs to have multiple drive bays, at least 4 and I would plan on having the capability of having at least 10 cards in the unit.  Might want to increase spacing between the card connectors, because things do get tight with say a TIPI with a PI mounted on it, and some HRD's that may have triple stacked chips.  Need visual access to the LED's on the existing cards as well.  Support for the cards with perhaps some Teflon or polypropylene slides to protect the edges.

 

I would not shorten the power supply requirements and plan on a pretty heavy load with the drives and cards.  Of course, that would be reduced with regulated voltage on the bus.

 

Your snap on design, I am not sure how you are thinking of designing it, but that worries me a bit for at least what I visualize.  You definitely do not want the ability where something could be accidentally separated while powered up.

 

I would also consider multiple fans in the unit if you are not going to step the voltage down.

 

As other folks have suggested, some photos/drawings of what you see would be most helpful when you reach that point as my mental picture is likely not your mental picture.

 

If you are strictly looking at miniaturization to just use something like 3 existing cards, I am sure it would interest some people, but not myself.

 

My penny's worth.

 

Beery

 

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2 hours ago, BeeryMiller said:

I am interested.

 

If the case can be "off the shelf readily available", then weight of the guts for the internals should be a high priority.  This will minimize shipping costs, especially to international customers where they can pick up a case overseas that would work and would just need some slip-in internals.

I like this idea a lot. I'll definitely consider it and maybe offer recommendations for mounting. I think if I make it somewhat universal, then this could be very useful. 

2 hours ago, BeeryMiller said:

Nobody has spoke of it yet, but the unit needs to have multiple drive bays, at least 4 and I would plan on having the capability of having at least 10 cards in the unit.  Might want to increase spacing between the card connectors, because things do get tight with say a TIPI with a PI mounted on it, and some HRD's that may have triple stacked chips.  Need visual access to the LED's on the existing cards as well.  Support for the cards with perhaps some Teflon or polypropylene slides to protect the edges.

 

Noted.

2 hours ago, BeeryMiller said:

Your snap on design, I am not sure how you are thinking of designing it, but that worries me a bit for at least what I visualize.  You definitely do not want the ability where something could be accidentally separated while powered up.

I believe that I might have been unclear here, but rest assured, there will be some sort of mechanical restraint in the connection, like a clip on the connector.

2 hours ago, BeeryMiller said:

 

If you are strictly looking at miniaturization to just use something like 3 existing cards, I am sure it would interest some people, but not myself

 

this is the exact line of thought that gave me the idea of making it modular. 

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It may be of interest others, but... consider those that want to go the expansion card route, there are plenty of P-Boxes available on the used market that are in excellent condition, so I have to wonder how re-inventing the wheel would compare price-wise with something that already does the same exact thing?   The size of the market is an important aspect as well.  The Classic TI market is not large to begin with and many of us have multiple systems already, so purchasing yet another empty box that takes up even more space may not be in the cards for many.  I say this rarely, but I think this is one I'll have to pass on.

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1 hour ago, GDMike said:

I'm really interested in seeing what the case looks like.

I'll probably upload a few images later tonight after my son is asleep. I will post a mock-up of some of the boards, and a quick (non-final) design for the case. 

 

I am definitely open to suggestions for the case, too. 

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17 minutes ago, Omega-TI said:

It may be of interest others, but... consider those that want to go the expansion card route, there are plenty of P-Boxes available on the used market that are in excellent condition, so I have to wonder how re-inventing the wheel would compare price-wise with something that already does the same exact thing?   The size of the market is an important aspect as well.  The Classic TI market is not large to begin with and many of us have multiple systems already, so purchasing yet another empty box that takes up even more space may not be in the cards for many.  I say this rarely, but I think this is one I'll have to pass on.

I appreciate your candor, but for me I haven't been able to find any boxes for a good price. I don't think paying $300 plus shipping for a used and abused box that someone found in their attic that I may have to repair is feasible, and I have all of the tools and equipment necessary to build something like this myself.

 

All this aside, I really do appreciate your time to post. Every comment helps me, especially the dissenting ones.

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A couple of thoughts here. There is a reason that there are seven cards connected to the flex cable card and the bus. The 74-series driver chips are designed to drive up to eight cards on the bus. The TI has logical provisions in place for up to 16 cards in total, but doing that assumes a split bus with two flex cable equivalents, each driving up to seven cards (eight if you make a 9-slot backplane or build the flex cable logic into the backplane). Go beyond this point carefully, as you may encounter all kinds of totally random errors on the bus that appear and disappear willy-nilly. One of the reasons I built my PEB Splitter cards was to allow two PEBs to be connected at the same time, as the flex cable card in each would never be driving more cards than the design limits, but you would still have a total of 14 available card slots if all of the cards in them were using different addresses. Several folks have run systems like this in the past, using the IEC splitter cable. That one sometimes ran into issues, introducing crazy errors due to the combined cable length (IEC+Flex Cable) being more than the 74LS244/245 bus drivers could safely handle. If the cables had been a few inches shorter, the problems would have been rare in the extreme (and limited to situations where the drivers wee weak already). My splitter avoided the length issue entirely by making the connection right beside the side port.

 

You might also want to take a look into the newsletters from the TI Users Group in Brisbane, as they outlined a simple, 3-slot PEB substitute which could be easily extended (I think it was from one of the issues in the early nineties). The advantage there is that the alternative to the Flex Cable is already part of the design.

 

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1 hour ago, Ksarul said:

A couple of thoughts here. There is a reason that there are seven cards connected to the flex cable card and the bus. The 74-series driver chips are designed to drive up to eight cards on the bus. The TI has logical provisions in place for up to 16 cards in total, but doing that assumes a split bus with two flex cable equivalents, each driving up to seven cards (eight if you make a 9-slot backplane or build the flex cable logic into the backplane). Go beyond this point carefully, as you may encounter all kinds of totally random errors on the bus that appear and disappear willy-nilly. One of the reasons I built my PEB Splitter cards was to allow two PEBs to be connected at the same time, as the flex cable card in each would never be driving more cards than the design limits, but you would still have a total of 14 available card slots if all of the cards in them were using different addresses. Several folks have run systems like this in the past, using the IEC splitter cable. That one sometimes ran into issues, introducing crazy errors due to the combined cable length (IEC+Flex Cable) being more than the 74LS244/245 bus drivers could safely handle. If the cables had been a few inches shorter, the problems would have been rare in the extreme (and limited to situations where the drivers wee weak already). My splitter avoided the length issue entirely by making the connection right beside the side port.

 

You might also want to take a look into the newsletters from the TI Users Group in Brisbane, as they outlined a simple, 3-slot PEB substitute which could be easily extended (I think it was from one of the issues in the early nineties). The advantage there is that the alternative to the Flex Cable is already part of the design.

 

Interesting. I will have to dig that up.

 

Thanks!

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I ran two P-Boxes for several years. The problems arose when the "arms" of the split cables were longer than 8". That was documented in a MICROpendium article, I think. 

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On 6/7/2020 at 11:09 AM, MrTransistor said:

Hello everyone. I am Mister Transistor.

 

I would like to share with you a project that I have been developing.

 

It is not a nano-peb type of device, and my goal is to allow existing expansion cards in a modern peripheral box.

 

I have the boards designed and played out, and I am still tweaking the power supply design. After this I will be moving on to systems design, i.e. arranging it in a chassis and prototyping.

 

Hello!

 

I've been looking at ways to mount backplane/cards in a common Hammond enclosure ($50-$90) and mATX form factor. I know you and others here want a bigger box (10-16 cards) but I am thinking of a smaller one with 3 cards (plus built-in flex) and a half-height bay. 

 

Another approach I pondered is a 4U server rack. These are expensive though.

 

On 6/7/2020 at 11:09 AM, MrTransistor said:

The whole reason I am writing this is to gauge interest in a device like this, and whether or not I will make more than one.

 

Further, if there is interest, I would love to hear about your thoughts on improving the design of the original PEB, such as the cable interface being awkward and bulky sticking out of the side of the console. (this is not a problem with my design however, but just an example.)

 

I have a hunch that a 50-pin SCSI cable would be a better way to connect a flex card to a console boot. Users could pick their own length (within limits).

 

 

 

On 6/7/2020 at 11:09 AM, MrTransistor said:

 

So far, I have a few things that I have decided on. First, miniaturization of the boards. To accomplish this and still retain backwards compatibility with existing cards, I have decided on a modular expansion slot board, where there are 3 per module, and this allows for a smaller box, or expansion of the existing box if so desired. Of course, expansion would require a beefier power supply, so there's that too. This can also be made smaller by sacrificing slots.

 

You said backwards compatibility plus a miniature size? How would that work? I don't think re-buying all the cards in smaller sizes is in the cards (sorry).. people DO want to use their existing storage controllers, and nobody has made a new floppy controller, plus chips are getting rare. Thierry's IDE as you can see from Shift838's build would be tough to make any smaller... though it has been done for retrobrewcomputers (formerly N8VM).

 

I'm looking at their DiskIO V3 IDE/floppy card, similar TTL implementation to Thierry's IDE. Its size is 160x100 EuroCard single. Compared to the a P-Box card at 195*150mm, that's about half the PCB area.  It uses a SMC 9266 FDC.

 

 

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2 hours ago, FarmerPotato said:

 

Hello!

 

I've been looking at ways to mount backplane/cards in a common Hammond enclosure ($50-$90) and mATX form factor. I know you and others here want a bigger box (10-16 cards) but I am thinking of a smaller one with 3 cards (plus built-in flex) and a half-height bay. 

 

Another approach I pondered is a 4U server rack. These are expensive though.

 

 

I have a hunch that a 50-pin SCSI cable would be a better way to connect a flex card to a console boot. Users could pick their own length (within limits).

 

 

 

You said backwards compatibility plus a miniature size? How would that work? I don't think re-buying all the cards in smaller sizes is in the cards (sorry).. people DO want to use their existing storage controllers, and nobody has made a new floppy controller, plus chips are getting rare. Thierry's IDE as you can see from Shift838's build would be tough to make any smaller... though it has been done for retrobrewcomputers (formerly N8VM).

 

I'm looking at their DiskIO V3 IDE/floppy card, similar TTL implementation to Thierry's IDE. Its size is 160x100 EuroCard single. Compared to the a P-Box card at 195*150mm, that's about half the PCB area.  It uses a SMC 9266 FDC.

 

 

 

By smaller size, I mean smaller interface cards. The goal is to allow use of existing full size cards. 

 

Further, the idea I mentioned earlier of modularity of the boards is that you can daisy chain up to 8 card slots by default, and perhaps in the future I will design a way to expand that further. This is an image of the interface boards. As you can see, the backplane board has two pin headers on either end, allowing a small jumper to be added. 

 

These are preliminary designs however, because a lot more refinement must go into it. I'll probably make a couple board layouts, because this one was pretty quickly done. 

 

It is also likely that I will design multiple versions to facilitate a "mix and match" solution for more peoples needs, but I don't want feature-creep to destroy the original plans.

mainboards.png

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