5150 expansion unit (a LOT of questions)

[bettablue]

I have a LOT of questions…

First off, I want to thank everyone for replying to my first post on the 5150 expansion unit. You have all been great! I am still quite confused about some of the requirements in putting one of these together and getting it to work with my 5150. Hopefully, by getting these questions answered, I’ll have what I need to get it done. :D

My other thread can be found here: http://www.vintage-computer.com/vcforum/showthread.php?24984-5161-expansion-unit

Here’s where I am now. I have been working on completing my 5150 computer system, and finally have everything worked out to collect the parts I need to build/refurbish, an IBM 5161 expansion unit for my new baby. I have been buying and selling other vintage computers and parts, mainly a few 5170 systems and keyboards; I’ve wheeled and dealed until I was blue in the face, but finally, I’m ready to finish assembling the hardware I need. Together with the information I have gotten in my other post about the expansion unit, I’m hoping that you all can cut through my uncertainty and simplify the process of getting one of these units working.

I know the 5161 is basically just a 5161 case with its own back plate for adding some additional expansion cards along with one or two 10 Meg hard drives. With the keyboard connector plugged, I know there will be little in the way of confusion when putting the system together. Storage is the primary reason I want the 5161, but there are other reasons for wanting a real expansion unit. I know there are probably other, possibly better, options available too, and I’m being quite particular here, but I know what I want. (I hope that didn’t come out wrong or harsh.)

I currently have or will soon have the following:

*1 transmitter card
*1 receiver card
*Hard drive(s)
*1 cable purchased fro from: http://cyberresearch.com/store/cables-wiring/pc-computer-cables/CBL_6203_7356.2.htm.

I also have a line on an original 5161 case and possibly the back plate, but that's not certain. :sleepy:

Is there anything else required to completely build this unit? Does the expansion unit require a proprietary back plate, or will a standard 5160 back plate be OK? Does the expansion unit also have its own main board or will the standard 5161 mother board work OK here too?

Final question: Can I convert a 5160 by adding the transmitter/receiver cards to the appropriate machines and use the cable to connect them? Could I also just take a converted 5160 and replace the front plate with one from the original case to complete "the look"?

I want to thank you all again. With answers to these questions, I should have the information I need to finish the job. I’ll post progress reports as things move forward.

 

[per]

The PCB from an 5160 cannot be used without isolating the bus (by cutting traces, except the power traces and the OSC line), and still then; slot 8 would be completely unuseable (as it's initially seperate from the rest of the bus).

The reason for this is because the receiver card is in controll of the bus in the expansion unit, and TTL logic don't like it when several devices controlls the same set of lines (except when the lines are "open collector"). In a regular unmodified XT, the bus is controlled by the motherboard logic.

I'm very certain the expansion chassis you have a line on contains the original PCB. It's generally just a bus and a clock generator; much like the S-100 systems and various other 1970's microcomputer motherboard designs. It's unuseable for anything else than the expansion unit, so I really doubt anybody removed it.

---

What's really interesting is that it's actually possible to convert an expansion unit into a 1970's-inspired microcomputer if a special ISA-compatible CPU board with front-pannel support was made. Of cours a custom front panel will have to be made too, in a size similar to the FullHeight drive-bay covers.

 

[eeguru]

Never heard of the 5161 till now. From the looks of it, it's just a bunch of TTL line drivers going to DB-25s - all passive. Pretty amazed it worked at all in the first place.

You could use any of the passive ISA back planes used in industrial computing. Lots on eBay. Most have P8/P9 AT style power connectors or terminal blocks. They don't have the local 14.318 MHz clock gen, but a good number of expansion cards don't use it. You probably would have to drill and tap new mounting holes for standoffs.

Post pics!

 

[bettablue]

5161 expansion

5161 expansion



I found these pics online. There are many more, but I currently don't have an actual unit, so I can't post what I don't have. In the 1st pic, the expansion unit is on the right, in the 2nd, the unit is the one on the bottom. Notice that there are no floppy drives installed on the expansion unit. That is because the expansion unit contains either one or two hard drives. Hope these helps.

 

[per]

View attachment 5659View attachment 5660

I found these pics online. There are many more, but I currently don't have an actual unit, so I can't post what I don't have. In the 1st pic, the expansion unit is on the right, in the 2nd, the unit is the one on the bottom. Notice that there are no floppy drives installed on the expansion unit. That is because the expansion unit contains either one or two hard drives. Hope these helps.

EDIT: Due to a minor missunderstanding, please disregard this message.

Ok. I am 100% sure that unit has the original PCB in it.

Just make sure to get a tracking number for the shipping of the unit (if you settle on a deal). If it dissapears in shipping, he'll problably not offer any kind of refund (speaking of previous experience). Don't blindly trust everything that guy says.

 

[MikeS]

Ok. I am 100% sure that unit has the original PCB in it.

Just make sure to get a tracking number for the shipping of the unit (if you settle on a deal). If it dissapears in shipping, he'll problably not offer any kind of refund (speaking of previous experience). Don't blindly trust everything that guy says.

Huh? Whom or what are you talking about?

 

[MikeS]

Never heard of the 5161 till now. From the looks of it, it's just a bunch of TTL line drivers going to DB-25s - all passive. Pretty amazed it worked at all in the first place.

It's a 62-pin connector, but yeah, it's just a powered ISA-bus extender to permit adding an HD and/or an extra card or two to a PC or XT (especially the PC with its puny power supply and at most 3 free slots).

Post pics!

Looks (and is) exactly like an XT except for the nameplate and the passive 'motherboard'.

 

[per]

Huh? Whom or what are you talking about?

EDIT: Due to a minor missunderstanding, please disregard this message.

That spesific image is from a spesific webpage, which is run by a spesific person. I once tried to buy a soundcard from him; he messed up the address, forgot to apply any form for return address and he then neglected to pay even a cent in refund.

I was not the only member here having issues buying/trading with him.

 

[mbbrutman]

Per- I don't think that BettaBlue was implying that he was buying anything from the person we affectionatley know as "FrozenFire75", or whatever it was. I think he just borrowed those pictures.

 

[TomFCS]

Never heard of the 5161 till now.

Post pics!

Here ya go.

 

[per]

Per- I don't think that BettaBlue was implying that he was buying anything from the person we affectionatley know as "FrozenFire75", or whatever it was. I think he just borrowed those pictures.

Ah. I missread the original comment, thinking that was the actual unit .

 

[MikeS]

Ah. I missread the original comment, thinking that was the actual unit .

Glad we cleared that up, since I think I'm actually the person from whom Bettablue wants to buy that 5161 chassis and I don't think I've ever sold anything here or on eBay...

Unfortunately AFAIK I don't have the backplane for mine, having removed it in order to replace it with a 486 Mobo back in the days when PC stuff was being tossed into dumpsters as just so much junk.

So, sorry Bettablue, but I can't help you either; the chassis, power supply and disk/controller combo shouldn't be hard to find (if you don't mind that the little square nameplate says XT), but the passive backplane (not backplate) is going to be a challenge unless you're prepared to use a substitute.

I always wanted to try an ordinary riser board (connected to the PS of course); I think I do still have the cards and cable somewhere, so maybe another rainy day...

 

[bettablue]

Correct. I have not purchased one yet, I only borrowed the pictures to show that it look like. Sorry for any confusion.

 

[bettablue]

That is exactly the case here. I think I replied somewhere else in this thread too, so sorry... But mbbrutman, you are correct. All I did was post pics I borrowed from the web. Sorry for any confusion.

 

[IBMMuseum]

...Unfortunately AFAIK I don't have the backplane for mine, having removed it in order to replace it with a 486 Mobo back in the days when PC stuff was being tossed into dumpsters as just so much junk...

...I always wanted to try an ordinary riser board (connected to the PS of course); I think I do still have the cards and cable somewhere, so maybe another rainy day...

I later regretted using an expansion chassis and backplane to host the Kaypro XT adapters (I had to cut the clock trace on the backplane to get it to work). It was what I could come up with as a replacement for a customer bringing in an IBM PC, that had a mouse get in the back, and corroded too much. I retained the PC chassis, but think I had to throw most of it out later.

Years later on I acquired a complete unit (not for sale), to go with the adapters I retained to make the misguided conversion...

 

[bettablue]

Well, if anyone has a line on a 5161 case unit, please send them my way, or let me know about where to look. Again, thanks everybody. You have been extremely helpful. It's really kind of sad that so many of these were thrown out as newer systems came along. But thatnks to you, I have a good start on putting one together.

Thanks again.