Netronics Explorer/85

[Dwight Elvey]

I would imagine any fully S100 floppy controller would work...there is a jumper to cut on the motherboard to disable the EX85 boot ROM and you'll need to disable the EPROM slots, and RAM slots on the motherboard. You will need more memory than the 4K from memory; no pun intended. The 64K JAWS memory card was designed to go with the EX85, but I'm sure others would work...I had some 8K 2102 based cards that worked fine, installed in my computer at one point. Yes, I have the schematics for the Floppy-1A but not the build instructions. The board layout is included. Dwight, the 5610 is the boot loader PROM for the board...I don't have a spare and have nothing to read mine with. Without that PROM, there's no point creating a clone of the board. The addressing problems with your switches, is likely to be the switches themselves...many of these DIP switch modules were notoriously unreliable, even back in the 70s and 80s. The 'jumper field' is actually a blank place to install an EPROM such as a 2708 or 2716 instead of the 5610 PROM. The two serial interfaces are for the console and printer...the EX85 SID/SOD console drivers are no longer implemented.

Although, not easy, one can write their own boot loader. It is software and assembly level stuff but not rocket science. I was putting together a NC4000 system. It is not anything like a microprocessor anyone is likely to come upon. It is know as a direct Forth processor. I purchased an old XT flopy disk controller card. I did not look at any software for a PC. I looked at the data sheet of the controller chip used. I wrote low level code to format, read and write the disk from scratch. Once to that point I also wrote code to read and write DOS disk using the older FAT12. I did this all with information found on the web. I wrote all the low level code myself. To say a card is useless without the ROM is only saying you don't have the slightest idea what the computer needs to do. Having a schematic of the card is a large advantage. All I had was the pinout for the PC bus.
There is nothing magic about writing code for hardware. It is worth knowing how things work. The more you know about things the better you'll be at maintaining it. Treating everything like a black box with a locked cover is a poor way to advise others. Learn to open the boxes. Treat each closed one as an opportunity not as a road block.
The EX85 comes with a monitor. It is not like there is no way to experiment. It is what it was made to do.
Dwight

 

[nomisimon]

Hi Dwight. I'm not sure there was a need for such a curt reply sir. The chap I was responding too asked originally if any floppy disc controller would work, which it should. Breadboarding an S100 floppy controller and writing the code for the boot ROM is a substantial task, even if you have the skills...which not everyone does. Back when these boards were new, I used to write code and design circuits too...I'm not an idiot. If someone is looking to recreate something from the ground up, fine...but I got the impression the chap was simply looking to get his machine up and running, and offered my opinion accordingly. The card is indeed useless without the PROM...unless you're prepared to spend the time writing the code for one. I could build a circuit to read my PROM...but am reluctant to in case I accidentally damage the only one I have. I joined this forum to ask for help where needed, offer my help where I could and to share information, not...with all due respect, to be scolded like a child. Simon.

 

[Dwight Elvey]

Hi Dwight. I'm not sure there was a need for such a curt reply sir. The chap I was responding too asked originally if any floppy disc controller would work, which it should. Breadboarding an S100 floppy controller and writing the code for the boot ROM is a substantial task, even if you have the skills...which not everyone does. Back when these boards were new, I used to write code and design circuits too...I'm not an idiot. If someone is looking to recreate something from the ground up, fine...but I got the impression the chap was simply looking to get his machine up and running, and offered my opinion accordingly. The card is indeed useless without the PROM...unless you're prepared to spend the time writing the code for one. I could build a circuit to read my PROM...but am reluctant to in case I accidentally damage the only one I have. I joined this forum to ask for help where needed, offer my help where I could and to share information, not...with all due respect, to be scolded like a child. Simon.

Then you should have said that. My earlier post was stating that one could work from a schematic, it was possible to write the code to make it work.
Your statement was without the PROM, it couldn't be done, makes the assumption that that person can't do it.
I don't know your skills or his. I know it is not a trivial task but not one that a person can't learn and it is worth doing so, as well.
As for your case, I'm assuming it is a PROM that has code running on the S100 bus. It is less of a task to write code for the S100 machine to send the data out a serial port. That is assuming it is not for some state machine on the board.
It is worth doing for your own sake, even if you don't have someone else that might want it.
Dwight

 

[mykrowyre]

Hi Dwight. I'm not sure there was a need for such a curt reply sir. The chap I was responding too asked originally if any floppy disc controller would work, which it should. Breadboarding an S100 floppy controller and writing the code for the boot ROM is a substantial task, even if you have the skills...which not everyone does. Back when these boards were new, I used to write code and design circuits too...I'm not an idiot. If someone is looking to recreate something from the ground up, fine...but I got the impression the chap was simply looking to get his machine up and running, and offered my opinion accordingly. The card is indeed useless without the PROM...unless you're prepared to spend the time writing the code for one. I could build a circuit to read my PROM...but am reluctant to in case I accidentally damage the only one I have. I joined this forum to ask for help where needed, offer my help where I could and to share information, not...with all due respect, to be scolded like a child. Simon.

Hi Simon, I don't think Dwight intended to insult anyone, I think he was just trying to encourage us to think "inside the box". I agree, though. I am a software developer, I know have enough self taught electronics knowledge to fix things (though rarely quickly), but the idea of writing disk access code in machine language for an unknown floppy controller is not something I have time or even desire for at the moment. I wish I had enough experience to just say hell yes I'll do that, but I do not.

I guess the answer then to my question "will any floppy controller work" is actually no... not without a significant amount of trial and error.

Reproducing the floppy controller sounds possible. Schematics, photo of the board front and back (which I have already), and a dump of the rom would be a good start.

 

[Dwight Elvey]

My intent was to inspire. A person might find that while not a trivial task, it is still not impossible for most anyone. When I first started, it all seemed to be mysterious and somehow beyond my reach. I've had very little formal schooling ( mostly vacuum tubes and amplifiers ).
You can't even guess what your limits are if you give up before even starting. There is so much more information available now on the internet.
I don't have a college degree above a AA. I've never stopped learning. The effort has payed off over and over.
Don't erect walls that don't exist.
Dwight

 

[mykrowyre]

My intent was to inspire. A person might find that while not a trivial task, it is still not impossible for most anyone. When I first started, it all seemed to be mysterious and somehow beyond my reach. I've had very little formal schooling ( mostly vacuum tubes and amplifiers ).
You can't even guess what your limits are if you give up before even starting. There is so much more information available now on the internet.
I don't have a college degree above a AA. I've never stopped learning. The effort has payed off over and over.
Don't erect walls that don't exist.
Dwight

Hi Dwight, I understood what you meant. I have been programming for 30 years as a career with no degree. I make as much as some doctors.... my wife who has a masters degree finds it extremely frustrating. Knowledge is there for those who seek it.

 

[Agent Orange]

My intent was to inspire. A person might find that while not a trivial task, it is still not impossible for most anyone. When I first started, it all seemed to be mysterious and somehow beyond my reach. I've had very little formal schooling ( mostly vacuum tubes and amplifiers ).
You can't even guess what your limits are if you give up before even starting. There is so much more information available now on the internet.
I don't have a college degree above a AA. I've never stopped learning. The effort has payed off over and over.
Don't erect walls that don't exist.
Dwight

Like you Dwight, I was raised on vacuum tube and transistors theory. What a way to start a conversation in a bar these days; "Hey Jim, did you know that in a class 'C' amplifier the grid draws current?" And Jim comes back with; "No I didn't, but the predominate characteristic within a PNP transistor is hole flow". So, where does one go with all of knowledge these days? Back in the 80's, when TI started with the throw away cards, and the hybrids came in doing the work of an army of components, I kind of felt that the trained/specialized repair guy's future might not be so secure.

 

[mykrowyre]

I put an 8" CDC-1 floppy drive up on ebay if anyone is looking for Netronics floppy drive parts. Starts at $25.

 

[wrljet]

Do you have the actual manual for the monitor. I too spent time dissembling the ROM but I now have the manual. I too am interested in the keypad ROM. I did discover a lot came straight from the SDK-85 monitor so I suspect the Keypad ROM does too. Are those the Basic ROMs in your board curious as to what is on the labels?

Link to Monitor listing and Basic user manual.

https://dl.dropboxusercontent.com/u/8496003/Netronics EX-85 manuals.zip

Hello James,

I was wondering if the Netronics EX-85 manuals.zip file is still available somewhere. The Drobox link no longer works.

Thanks,
Bill

 

[AstronomyGuy]

Thanks nib!

I seem to recall reading in one of the online copies of the docs that the 'ikbd' chip was the ROM monitor? Is that correct? For some reason I can't find it now.

That reminds me... has anyone heard from James0555 recently? A couple years ago I sent him the ROM from my /85. Had the rarer keypad monitor. He dumped it and was going to send it back but I never heard from him again. Hope he is ok.

Hi Tech Time Traveler (I recognize your logo from your YT channel) -- did you ever get your Explorer 85 going? I have one that I finally got going after a lot of debugging down rabbit holes. (I think I was one of the people who beat you to it on eBay back in 2017). The "ready" LED never lit and it didn't look like it was ever running proper code. It turns out the issue was a completely hosed 8355 ROM. I got a burner for 8755A and made a new terminal version ROM (EPROM), and it booted successfully. If you need an 8755, let me know.

Responding to your other questions -- yes that's a DB25 for serial. Here's the pinout I found in the docs:



BTW I found that the serial timing is way off -- not sure if it's a general bug or just my unit, but anything above 1200 baud won't work (2400 partly works but is flakey) -- using a scope I found out that the timing is too fast -- e.g. when I try 4800 baud and it auto-detects the space bar, it transmits the response at about 5500 baud. It seems like whoever programmed the monitor was assuming a different clock speed (but it has the 6.144MHz crystal in it as specified). Oh well. Maybe the crystal could be replaced with a slower speed that makes it work.

I also burned some EPROMS with BASIC and got that working also.

Now that I got it going, I'm going to sell it on eBay -- probably listing it tomorrow (as an auction). It's a nice unit and fun to play with, but I have plenty of S100 computers.

 

[falter]

I never got mine to the point where it would run BASIC. I was trying to figure it out, Dave was helping me, but I began finding some changes/damage that I suspect may be causing some issues. As usual I got distracted by something else but now that I have another workspace free I might take a run at it. I think that's your auction that popped up this AM? Would you be willing to send me high res photos of both the front and back of your board? I just want to check as I think the original user did some mods to mine that are haunting me now.

 

[AstronomyGuy]

I never got mine to the point where it would run BASIC. I was trying to figure it out, Dave was helping me, but I began finding some changes/damage that I suspect may be causing some issues. As usual I got distracted by something else but now that I have another workspace free I might take a run at it. I think that's your auction that popped up this AM? Would you be willing to send me high res photos of both the front and back of your board? I just want to check as I think the original user did some mods to mine that are haunting me now.

I just saw this today -- I was hoping the forum would E-mail me when you replied but I guess it doesn't work that way. Yes that was my auction. It shipped, but I can send you the photos I took for the auction, which should be higher res than the eBay version. I'm not sure if I should post them here or try to E-mail you. I believe you're also the person who just bought the MIKE-2 I was selling, right? If not, I connected the dots all wrong. If so, send me an E-mail and I can get you the photos that way. I don't see a way to PM here, maybe I'm too new.

Regarding BASIC, did you use the steps in the BASIC docs to load the registers and then Go? It was also necessary to connect what I call the "pause" input pin on the 8355/8755 (mentioned in the docs) so it's not floating so it can print more than one line at a time.

 

[Moonferret]

I spotted that MIKE-2 last night and was debating whether or not to put an offer in. Luckily, for my bank balance, it had sold when I hit refresh later on!
Sounds like it has probably gone to a good home anyway

Cheers,
Dave

 

[wrljet]

I still have a box from Netronics, dated 1981. No idea what they sent me in that size box.
It wouldn't have held the Explorer/85, not large enough. Been storing ICs in it for decades.

Postage/UPS was certainly cheaper back then!

 

[falter]

I still have a box from Netronics, dated 1981. No idea what they sent me in that size box.
It wouldn't have held the Explorer/85, not large enough. Been storing ICs in it for decades.

Postage/UPS was certainly cheaper back

What dimensions are the box? I have a box just like it, with a complete unbuilt EX/85 in it.

 

[falter]

I just saw this today -- I was hoping the forum would E-mail me when you replied but I guess it doesn't work that way. Yes that was my auction. It shipped, but I can send you the photos I took for the auction, which should be higher res than the eBay version. I'm not sure if I should post them here or try to E-mail you. I believe you're also the person who just bought the MIKE-2 I was selling, right? If not, I connected the dots all wrong. If so, send me an E-mail and I can get you the photos that way. I don't see a way to PM here, maybe I'm too new.

Regarding BASIC, did you use the steps in the BASIC docs to load the registers and then Go? It was also necessary to connect what I call the "pause" input pin on the 8355/8755 (mentioned in the docs) so it's not floating so it can print more than one line at a time.

Yes that was me! Really excited on the MIKE. I tried to refresh myself on that machine and remembered there's only two bits of info - both from lcfgroup before they merged with the Computer Museum of America or whatever it's called now. I think this machine is either a MIKE-3 (303) or a MIKE-2 that was upgraded later. I've been trying to pin down when the MIKE first arrived through magazine articles but the earliest I've found is mid 1975. I suspect the 8008 version must have come out before that - David Larsen suggested the MIKE-2 was the first machine to use the 8008 (which doesn't jive with official sources). Or maybe at the same time/close to when the MIKE-3 appeared. Still really excited to have this and get it running!

Yes daver2 and I did some troubleshooting with it. IIRC essentially it wouldn't map the contents of the BASIC ROMs into any address space. So there was nothing to run at the address they were supposed to be at. I listed out the whole memory space one day and they just weren't there. We fiddled, I tried scoping various lines trying to track down the problem but then got busy with something else. My board had been hacked around a bit, so I was hoping if I had a really good photo I could do some detective work and maybe spot something cut/jumpered that shouldn't be.

If you want to send them to me at brad at techtimetraveller dot com that works. Much, much appreciated!

 

[wrljet]

What dimensions are the box? I have a box just like it, with a complete unbuilt EX/85 in it.

Cool!

My box is ~ 13" x 9-1/2" x 2".
I got my (original) Explorer/85 in 1979, if I remember correctly. So the box wasn't from that.

/Bill

 

[AstronomyGuy]

Yes daver2 and I did some troubleshooting with it. IIRC essentially it wouldn't map the contents of the BASIC ROMs into any address space. So there was nothing to run at the address they were supposed to be at. I listed out the whole memory space one day and they just weren't there. We fiddled, I tried scoping various lines trying to track down the problem but then got busy with something else. My board had been hacked around a bit, so I was hoping if I had a really good photo I could do some detective work and maybe spot something cut/jumpered that shouldn't be.

I E-mailed you separately, but posting here in case others need the info.. and attaching photos if possible (not sure what my limits are)

On the back, all of the red wires were mods that were made that all have to do with the S100 bus (some going through chips on the prototyping area). I inspected them all carefully, and also looked for cut traces. The only cut trace of consequence was for one of those mods, which I repaired and trimmed back the mod -- that was on U114. So as far as I can tell, the stock board (as with my board once it worked) should have no cut traces.

There are 2 large blue wire jumpers on the front which are designated as required by the docs (I think for one of the "level" options) for jumper points W, X, Y, and Z I believe.

The one mod I made for BASIC was the blue wire on the back, from U105 to the Interrupt switch to enable the pause function (without it, it's floating and always pauses). There was already a bodge running from that switch up to the 24-pin socket, so I just jumpered U105 to that point.

Just some debugging thoughts, not knowing what you've done so far... probably some silly/obvious, but...

This is all based on the Rev. C board, not C.1 which has a few differences, so be careful which online docs you reference. BTW, I scanned all docs I had and will be putting them on Archive.org.

Did you test the BASIC EPROMs in a programmer to make sure they're good? Maybe bad 2716's. Obvious I know -- but I tried programming the BASIC EPROMS with a TL866 at first, they seemed OK but went crazy -- I finally realized that the TL866 only has 21V so it wasn't programming it properly even though it seemed to verify. I used a proper 2716 programmer and that solved it.

It needs to have all Level B (and D/E) options installed. That should basically be all U2xx and U3xx chips.

I set the RAM select (SW201 I think) for 0000 since BASIC needs RAM there, and of course the EPROM select for C000

The jumpers on the EPROMS (S12-S15 I think) should all be jumpered A-C

For all other jumpers, I followed the steps in the construction docs (I don't remember if any were different after the mods)

That's all I remember having to do, besides replacing a couple chips, including the 8355 (but that was needed to get the monitor to work).

 

[AstronomyGuy]

I still have a box from Netronics, dated 1981. No idea what they sent me in that size box.
It wouldn't have held the Explorer/85, not large enough. Been storing ICs in it for decades.

Postage/UPS was certainly cheaper back then!

Netronics also made the ELF II which is smaller than the Explorer, and also several S-100 cards. maybe it was one of those?

 

[wrljet]

Netronics also made the ELF II which is smaller than the Explorer, and also several S-100 cards. maybe it was one of those?

I never had anything else from them that I can remember, except the monitor listing. Figure I got that before 1981, too.
Dunno. Mystery lost to the ages, unfortunately. (along with my original Explorer-85)