Search found 64 matches

by inmbolmie
30 Jun 2020, 15:12
Forum: Off-topic
Topic: IBM 5170 help
Replies: 8
Views: 316

Re: IBM 5170 help

I'd suggest if you have a CGA card and don't need to keep it original to directly get any cheap 16 bit ISA VGA card off ebay. CGA is underpowered for a 5170 and the VGA card will be even cheaper than an adapter. But if you have an IBM CGA you will also have a single RCA connector in that card that i...
by inmbolmie
30 Jun 2020, 11:57
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

Interesting project! Apparently someone made a similar converter for 3270 around the same time as OP. https://ajk.me/building-an-ibm-3270-terminal-controller Wow, thanks for pointing it out! It was a big coincidence, both in timing and in concept. In January-February I searched throughfully online ...
by inmbolmie
24 Jun 2020, 13:07
Forum: Workshop
Topic: Honeywell Micro Switch and USB interface
Replies: 8
Views: 402

Re: Honeywell Micro Switch and USB interface

I like this concept of "piggybacking" the existent controller, it is clever and allows to keep the keyboard as original as possible.

How do you plan to power the original controller? From the USB? Does it require any weird voltages?
by inmbolmie
23 Jun 2020, 20:49
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

I have received the final PCB boards, much more pleasant to look at that the DIY thing. board_final.png Assembled board board_assembled.png Everything works fine with them, there are no layout errors in the final design so I feel that for a first version, this project is finished and is sufficiently...
by inmbolmie
20 Jun 2020, 13:04
Forum: Keyboards
Topic: Do I need to screw mod my Model M?
Replies: 13
Views: 575

Re: Do I need to screw mod my Model M?

My policy: All the keys sound and feel the same ---> OK Not uniform keyfeel, too pingy or too mushy ---> Partial screw mod The thing falls apart or comes from a swamp ---> Complete screw mod In your case it seems that there are much less rivets in the bottom rows and in the numpad zone, so check tha...
by inmbolmie
17 Jun 2020, 22:24
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

I expect to have the first batch of PCB's in my hands next week, they are already made and in transit from the fabricator, so if anybody is interested (out of who already have contacted me) please send me a PM. I will make only a handful of devices and only by demand, as the components aren't specia...
by inmbolmie
14 Jun 2020, 00:31
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

I've uploaded the PCB files to the repository . So now, "version 1" of this project is ready and anyone with a desire to do this by itself has all the necessary information published. The final result looks like this: PCB.png I've also been finally able to test the converter with real Twinax cables,...
by inmbolmie
13 Jun 2020, 15:08
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

Hi, here's a quick update - your comment on an "auto-configuration-feature" made me searching the net ... Unfortunately all that documentation is about the SNA/SLDC protocol, that is a network protocol related but totally different from the Twinax protocol. As eeguru said earlier in this thread, th...
by inmbolmie
10 Jun 2020, 23:17
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

It’s time for the application layer (layer 3) stuff, the Python script for protocol conversion and session management. I have uploaded the code (5250_terminal.py) as well as some basic instructions to run and configure it to the Github repository: https://github.com/inmbolmie/5250_usb_converter The ...
by inmbolmie
08 Jun 2020, 23:37
Forum: Keyboards
Topic: Training Video for the IBM 029 Keypunch
Replies: 4
Views: 304

Re: Training Video for the IBM 029 Keypunch

Thanks, I enjoyed it very much
by inmbolmie
06 Jun 2020, 19:31
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

A short comment would be very much appreciated, what the (dis-)advantages would be. (Beside the availability of the chip.) The availability of the DP8344 is not an issue, but there are three main reasons for me not to use it for this project: One, as you said, is that the DP8344 is a pre-USB era de...
by inmbolmie
04 Jun 2020, 12:38
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

...I am quite confident that we will receive an answer - if we are lucky with the document attached. :-) It would be very nice to get that document, I have already read the rest of available documents that you mentioned. There are even several revisions of that document that include "AS/400" inform...
by inmbolmie
01 Jun 2020, 12:26
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

Regarding the operation - I read the documentation you provided in this document and as far as I understand there is some software that has to be loaded into the arduino/teensy at startup (You provided the github link). At some other place some python code was mentioned. Is this still required OR i...
by inmbolmie
31 May 2020, 20:29
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

So if you decide to build a small batch of this interface (as a "plug-and-play"-solution, just for plugging it into the Hardware and the mains) I would be very interested in buying one. (Depends on the price you ask for, of course - so some price-information upfront would be very much appreciated b...
by inmbolmie
25 May 2020, 00:14
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

This weekend I've been trying the converter using an ISA 5250 emulation adapter card for IBM PC that I got some time ago. The card is hooked up to an IBM 5160 PC (with its proper model F XT keyboard to get the full retro experience) and a couple of interesting things came along with those tests. Fir...
by inmbolmie
20 May 2020, 09:51
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

... the diff receiver has problems when the pair is idling at ground. It picks up slight bias and registers an analog change of just a few millivolts as a binary transition. It's not a huge problem as the sync pattern should be the threshold of interpretation. But it would simplify logic/code if th...
by inmbolmie
19 May 2020, 20:45
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

It’s time for layer 2 components, essentially frame format and Teensy code. About the frame format, it is really well documented in the sources linked before, and there isn’t much that I can add here to that, but I will give a brief description. Each frame is 16 bits long (or 32 half-bits). Each tra...
by inmbolmie
18 May 2020, 22:42
Forum: Workshop
Topic: IBM Model F122 Modifications Help
Replies: 9
Views: 582

Re: IBM Model F122 Modifications Help

My main concerns are around the space bar removal ... The F122 spacebar isn't like the F-XT or the F-AT, it has nothing special and can be removed like a model M spacebar as it is not attached to any internal structure. As long as you do it carefully and don't break the clips that hold the stabiliz...
by inmbolmie
16 May 2020, 14:37
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

Are there any docs/pages in the bitsavers archive you've linked above I should explore further? First, I have to say that I'm not familiar with all those IBM protocols, outside the very narrow knowledge needed for this particular project, and a month ago not even that. There is one document referen...
by inmbolmie
14 May 2020, 22:29
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

Now the details for the “layer 1” of the converter, the physical interface to the Twinax terminal. For the explanation about the Twinax signal and cabling I think that the general description from Wikipedia is fine and I wouldn't explain it better, so I copy the relevant parts here from https://en.w...
by inmbolmie
11 May 2020, 18:09
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

Thanks for your comments, are much appreciated. For the technical details I will proceed in this way: First in this post I will comment the project in general as well as some design decisions, and later I will give the complete details about the software components as well as the physical circuit (B...
by inmbolmie
10 May 2020, 11:48
Forum: Keyboards
Topic: New ThinkPad Trackpoint Keyboard II
Replies: 24
Views: 1683

Re: New ThinkPad Trackpoint Keyboard II

.I really like that nav layout, especially page down and up next to the arrow keys. Actually, now that I think about it, you know what's fantastic? The numpad nav cluster, if only it used an inverted T arrow layout. That's ideal. Give me those Home, End, Page Up and Page Down right there with the a...
by inmbolmie
09 May 2020, 18:11
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

Re: IBM 5251 terminal USB conversion (but not what you think)

Should you ever consider building such a device for others, I would be very interested. Sure, I still have to make a PCB design, but I will get in touch when I'm ready to make the real board. I see myself telnetting into a MUD with that terminal and kill some orcs. That's a great idea that I will t...
by inmbolmie
09 May 2020, 00:50
Forum: Gallery
Topic: IBM 5251 terminal find
Replies: 9
Views: 785

Re: IBM 5251 terminal find

Follow-up workshop for this terminal, IBM 5251 terminal USB conversion (but not what you think)
by inmbolmie
09 May 2020, 00:46
Forum: Workshop
Topic: IBM 5251 terminal USB conversion (but not what you think)
Replies: 47
Views: 2989

IBM 5251 terminal USB conversion (but not what you think)

This is a continuation of this post where I describe an IBM 5251 terminal I recently found. It is about a USB conversion, but not what you think... terminal.jpg This terminal is in good shape and doesn’t need a restoration at all, it doesn’t even need a deep cleaning, so an obvious question was what...
by inmbolmie
06 May 2020, 15:55
Forum: Gallery
Topic: IBM 5251 terminal find
Replies: 9
Views: 785

Re: IBM 5251 terminal find

Very nice. I also got a 5251 terminal/screen some time ago - to keep my keyboard company. (The weight of this thing is unbelievable :shock: .) I think you're very lucky, that your terminal still has that cover in the front of the stand, where the cable comes out. So far I haven't even seen a photo ...
by inmbolmie
05 May 2020, 20:47
Forum: Gallery
Topic: Self Quarantine Project
Replies: 19
Views: 1491

Re: Self Quarantine Project

Very beautiful indeed! I've been thinking of doing something like this for a time, and this is inspiring. Thanks for sharing it.
by inmbolmie
05 May 2020, 17:23
Forum: Gallery
Topic: IBM 5251 terminal find
Replies: 9
Views: 785

Re: IBM 5251 terminal find

John Doe wrote:
05 May 2020, 17:18
Is it the one listed on ebay weeks ago and soon gone fast?

Nice find, congrates.
No, this was a local deal in Spain.I can't imagine what the shipping cost would be for something like this on ebay...
by inmbolmie
05 May 2020, 17:13
Forum: Gallery
Topic: IBM 5251 terminal find
Replies: 9
Views: 785

IBM 5251 terminal find

This is the second part of a great "barn find" where I also got an IBM 5100 and some rusty printers. First post is here . Due to space problems in my apartment I had until recently this IBM 5251 terminal in storage. But now with the pandemic and so I have had more time to clean and test this beast. ...
by inmbolmie
20 Apr 2020, 16:25
Forum: Other external
Topic: Great/Interesting Finds
Replies: 23506
Views: 1662501

Re: Great/Interesting Finds

So you are in Britain, love 80's vintage stuff and have a lot of empty space... This is your auction (includes some dirty keyboards of course) https://www.ebay.co.uk/itm/Job-Lot-Vintage-Computers-untested-IBM-BBC-COMPAQ-AMIGA-DRAGON32-TOSHIBA/124158364556?hash=item1ce86a4b8c:g:8k8AAOSwgmRemxUy s-l16...

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