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Bus Tag Host Emulators

NeXT

NeXT

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I got asked about this last night because I had asked about this very thing here probably 15 or so years ago but I can't find my thread on it anymore. The gist is they are trying to run an IBM 3420, but without the need for a similarly aged IBM 360 or 370, so converting the BUS/TAG interface from the 3803 controller to something remotely more modern is the preference. I'm older and wiser now. This way over my skillset.

I know IBM sold at least two Microchannel variants of host adapters for parallel channel BUS/TAG systems from IBM. The 02G7425 FC (2755) Block Multiplexer Channel Adapter (Type 5-2) and the 65G1828 FC (2759) S/370 Channel Emulator/A (Type 5-4). said individual has both cards and the ADF's presumably but no documentation or software has ever surfaced. Back in ye day I had this grand idea to attach one of IBM's older BUS/TAG channel tape controllers and drives to a much newer machine, you know like how we do for Qualstar drives using Pertec. I recall I got lectured on this and how that while yes, that would be a correct electrical connection, that would not work because the protocol and data flow as not the same. Likewise, good luck finding the drives and controller. (well, someone did, but I don't make that kind of money! :P )

More recently however LGR found/received in an IBM Industrial PC another variant of BUS/TAG interface in the form of a turbo oversized ISA card. The details of which are posted here on the forums somewhere but with that card it seems we all settled on it was going the opposite direction and the machine was using to card and the industrial PC to emulate a peripheral rather than control it. Late in the game I am also aware that IBM was supporting PCI interface "parallel channel adapters" (it's BUS/TAG) under linux/Unixware using FLEX-ES for the emulation both directions and that I can tell that seems more in line with what we had been hoping to see, but even information on this seems to be scattered about and so far I've not seen signs the cards much less the software has survived.
FLEX-ES_PC.jpg
( https://www.redbooks.ibm.com/redbooks/pdfs/sg246498.pdf )


I'm sensing again that cold chill I seem to get whenever I ask the IBM folks about hardware or software because they are all afraid IBM Legal is going to strike them down like the hand of god if they disclose anything. Can I at least try and spur a discussion?
 
If I'm following correctly they have a parallel channel device (or CU) but want to connect it to a modern host?

I've been working on and off (more recently off) on a bus and tag interface, I've got a 3174 connected to Hercules and working reasonably well:

github.com

GitHub - lowobservable/channel: IBM parallel channel adapter

IBM parallel channel adapter. Contribute to lowobservable/channel development by creating an account on GitHub.
github.com github.com

It's in a sort of proof of concept stage, still a long way to go.
 
I have an IBM 3420. Realistically I will never have this running on any bus/tag interface so I acquired an IBM 3420 Field Tester to exercise the drive.
This small box has a bunch of control switches and thumbwheels and plugs into the 3420 backplane via a ribbon cable with a standard SLT card connector.
It at least would allow the drive to rewind, fast forward, seek, read/write at different BPI so that would be enough for me to demo it.
 
I used to walk through a data center that had some IBM 3480 drives connected with bus & tag to escon converters, they were little rounded off things sitting on a rack mount shelf, probably the IBM 9034. This was ten or more years ago, like Z10 era, so I assume at some point they had to convert from escon to ficon, but I’m not sure how that happened. Maybe IBM still supported escon natively back then?
 
jafir said:
I used to walk through a data center that had some IBM 3480 drives connected with bus & tag to escon converters, they were little rounded off things sitting on a rack mount shelf, probably the IBM 9034. This was ten or more years ago, like Z10 era, so I assume at some point they had to convert from escon to ficon, but I’m not sure how that happened. Maybe IBM still supported escon natively back then?
Click to expand...
You could still order ESCON channels at least as late as z9, which is the last time I personally had to generate an IOCP.
 
OK, not sure why, IBM folks are nervous. IBM is fine on 360 or 370 emulation, and the old 360 type channels are documented :-


I would say your best option is to look for an old server because the hardware isn't hard but the software is. So a P370, P390 with the necessary cards, or a Multiprise.
These are all small systems, and will run the free versions of VM or MVS.
I would be asking every where I could, including on the main IBM groups if any one would sell one of these.
There are still subscribers on the p370 list at PUCC, could ask there.


lastly perhaps talk to the flex folks...

Fundamental Software, Inc., FLEXCUB Whitepaper, 2005-02

Fundamental Software, Inc., FLEXCUB Whitepaper, 2005-02
www.funsoft.com
 
OK, not sure why, IBM folks are nervous.
Click to expand...
It's the worst kept secret in the history of computers but most of us are not uh, compliant with software licensing that is dictated by IBM. ;)

The gist I tend to see is that the hobbyists who are into IBM midrange and mainframe don't talk about license cracking or sharing software like one would see with the micros or even other minis, even privately in outer email circles and mailing lists because there's still the enterprise hold-outs still running truly ancient machines or licensing full system emulators from IBM because for one insane reason or another they do not have an upgrade path. If we want to tangent to find an example for the micros, Cloanto Corporation has sent people I know legal threats because a vendor ratted them out for hosting an image of the Amiga Kickstart ROM. While the losses incurred from sharing a 30+ year old ROM isn't a whole heck of a lot, I can only imagine the cost to be running a 40+ year old IBM system is astronomical. The last thing any of them need is someone to find a license crack (see above about needing a valid license to even add an additional channel), run off with it to support their own system and then either someone errantly contacts IBM assuming the product WAS licensed properly or the hardware of an existing contract reports the license change and IBM sees it during a support request. IBM would immediately find out where it came from and have done so in the past when some of the shadier IBM resellers were sued out of existence. Nobody wants to be the person who resulted in a support contract going up for immediate renegotiation because there was a violation in the T&C.
So a lot of people who work in the field either as a hobby or as a full-time job tend to say nothing and share nothing, even if it's a configuration utility or other benign software component/documentation, just in case the person asking is IBM feeling around for people trying to skirt the terms of their contract.
 
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What about creating some piece of hardware that does bus&tag and then write adaption code for Hercules?

Edwin & Henk made a 3705 emulator that connects as a bus&tag channel using TCP/IP to Hercules. https://github.com/snhstq/IBM3705_R5/blob/main/Hercules files/comm3705.c
Something similar could be done when connecting a real 3803 to Hercules I guess. Not saying it is super simple to do but I think it would be a way to connect 3420/3803 to something more ”modern”. Although not IBM at all but emulation.
 
MattisLind said:
What about creating some piece of hardware that does bus&tag and then write adaption code for Hercules?

Something similar could be done when connecting a real 3803 to Hercules I guess. Not saying it is super simple to do but I think it would be a way to connect 3420/3803 to something more ”modern”. Although not IBM at all but emulation.
Click to expand...
I've been working on something like that, at least enough to connect a 3174-1L (bus and tag) to Hercules:

github.com

GitHub - lowobservable/channel: IBM parallel channel adapter

IBM parallel channel adapter. Contribute to lowobservable/channel development by creating an account on GitHub.
github.com github.com

The project is lacking any documentation but it is esentially what you descibe - a generic channel device in Hercules sends the channel commands over to the interface via TCP/IP and the interface handles the bus and tag.

I responded earlier but I think my message was hidden awaiting approval.

I'd be happy to work with the OPs friend if they are willing to do some testing, a tape would be a lot more fun than a terminal :)
 
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