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IBM RT PC experts?

MattisLind

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Any IBM RT PC owners out there?

I have an IBM RT PC that I would like to get working. It is a 6150 tower. I also have a megapel board, the 5081 screen, keyboard and mouse.

Many years ago the battery was removed and it was started up. The LED indicators stopped at the hard disk step. Presumably because of a bad hard disk.

I tried to read up a bit. It seems that all hard disk adapters supported on the RT uses approximately the standard AT hard disk register set. Would it be possible to use a standard ISA IDE adapter on a RT? Connected to a Compact Flash card?

Anyone that has done something similar with their RT PC?
 

snuci

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Is the hard disk not an ESDI drive? The card is an Extended ESDI Adapter board so it may even not be 100% normal ESDI compatible?

Nice. I wish I had the 5081 screen. I am missing that and have not tried to power up my 6150 yet.
 

bear

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You can only use ISA IDE with a patched 4.4BSD. I'm not sure if you can boot from it, I can't find the FAQ references to that, now. Maybe.
 

MattisLind

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Yes. According to the Tech ref volume 2, there are four different hard disk adapters for the RT PC. One is IBM AT fixed disk adapter that snuci mentioned, the others are various types of ESDI adapters.

My understanding was that an IDE adapter + drive is basically the same as an AT disk controller. If that holds then it might work.

But then bear mentions that it only works with a patched BSD 4.4.

Please elaborate a bit more why the standard AT adapter is working and not a ISA IDE adapter with IDE disk.
 

MattisLind

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I cleaned up the 6150. It is a B25.

Originally there were a 5080 Attachment adapter. But since I don’t have one I removed it and installed the megapel board.

I have a keyboard and mouse from the 6151 which was battery damaged. With keyboard installed it stops at status code 09. Which is keyboard controller POST error. Without keyboard it continues to 22. Which is no boot record found. Then it tries to boot off the floppy.

So is there some kind of trouble with the keyboard. A 6151 keyboard should work ina 6150 right?

Is there something like keyboard disabled? I was thinking perhaps that it somehow anticipated keyboard input from the 5080 system rather than the built in keyboard port?

Nevertheless the 310 Meg Maxtor seem to have no boot record. I will try to make diagnostic floppy to see if that could give more info. But a keyboard would be nice to have working.
 

MattisLind

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"Messen ist wissen" said late Werner von Siemens. I built myself a small gadget to be able to measure what was going on on the keyboard cable. The logic analyzer did indeed catch something. It looked like the code 0x79. Apparently a scan code that was repeated all the time. Perhaps a stuck key? 0x79 is the ENTER key on the numeric keypad. Prying it loose and checking. Nothing obvious except for the small metal wire used to guide wider buttons wasn't attached properly. Since I didn't find anything obvious I didn't think it would help. But it sure did. Now it passes step 09 and goes on to step 22.

I guess I need to make myself a USB stick with all floppy images to use with a Gotek. Perhaps running the diags would allow me to understand why it isn't booting. I wonder how much info is needed to be present in the CMOS powered memory? Obviously the battery has been removed (it killed my 6151).

Another question if the megapel board show anything on screen when running the diags floppy? I could throw in a MDA adapter, but I have no MDA screen nearby.

BTW I have 5080 attachment adapter that I could trade for something interesting...
 

snuci

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Now it passes step 09 and goes on to step 22.

Interesting. I thought it would die at 23 unless 22 also includes battery powered memory.

Error 22 - An attempt is being made to do an IPL, using the default
devices specified in the ROM on the processor board.

Error 23 - None of the IPL devices specified in the battery-powered
memory or the ROM default list could be identified.

Looks like you will need a battery. I removed mine long ago as well.
 

bear

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You don't need a battery to IPL, I've been running mine without a battery for ages.

I've actually been looking for a 5080 attachment card for some time. What kind of trade might you be interested in?
 

dkarguth

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Another question if the megapel board show anything on screen when running the diags floppy? I could throw in a MDA adapter, but I have no MDA screen nearby.
It should, I did all the diagnostics on my RT with the Megapel board installed. Out of curiosity, which model of 5081 do you have? I've been searching for one for a few years now, I don't have one for my Megapel. I've just been using a BNC to VGA adapter and a flat panel monitor
 

MattisLind

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I don’t have the exact model here right now. I got it thirty years ago. I think it came together with a 5085 back then (which I scrapped unfortunately…)

Back then I used it with my Linux PC and managed to configure XFree86 to show a nice display. Around 1280x1024. I made a special sync-on-green inserter to make it work with a SVGA board.

It is incredibly heavy and very deep. Not suitable for an ordinary desk.
 

MattisLind

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vvuH6LPl.jpg


UfOHvfBl.jpg


Very IBMish. It looks like I need to call my service representative.

The megapel adapter worked just fine in the diagnostic. It is just the display that has a few issues. The D drive, an E70 ESDI drive seems to be toast. The C drive, a H310 drive, is passing all the diagnostics.

It diags keeps complaining about card moved or not present. I removed the MDA card, the 5080 card and the Lighted Keyboard (aka quad async board) and then moved the 6157 board. It just doesn't seem to stick when I tell I have removed or moved them. Why is not the 6157 detected in its new position? Strange.

For now it just detects the newly installed Megapel board (slot 4/5) , the token ring board (slot 8) and the ESDI board (slot 1). The 6157 board in slot 2 is not detected. Strange. Does the 6157 streamer need to be connected to have the board detected? I guess not, but one cannot be sure.

It won't boot. Bear wrote that it will IPL without battery in place so I guess that with a good working bootable drive in C it should boot. Even though the C drive is working so I guess that this means that the drive is wiped, right? I have removed the non-working E70 in D but that didn't help. Still no boot.

Next step would be to try to do a new install of AIX and see if I can make it boot then. In the long run I would like to replace the H310 with CF flash disks if possible. There is the R40 and R70 which in my interpretation would be MFM disks. Possibly these could be emulated on a CF card connected to a IDE adapter? I thought the diagnostics disk would allow me to configure the disks connected to the system like one could do with the IBM AT. But it appears not be the case. On the other hand the ESDI allow you to read out the drive type from the drive so in the case for ESDI it would not be necessary. But how does the RT handle MFM disks?? Where is the disk geometry specified?

I don't have the humongous 5081 nearby. It is a SONY Trinitron screen. But there are pictures of the 5081 online. Like this picture from CHM:

IBM.RISC.RT_6150_model_A25.5085.6157.6153.5083.ca1986.102657027.lg.jpg


The difference is that my to be setup is to connect the 5081 monitor (the one to the right) directly to the IBM RT PC using the Megapel board.

I have picked up parts for this system over the years. I got the 6150 some 8 years ago. Since it was a B25 it had the 5080 interface stuff in it. Back in the early 90ies I got the 5081 screen which I connected to a Linux 386 machine running XFree86 back then. Made a small VGA to sync-on-green device that connected it to the PC VGA card. I then tweaked the XFree86 config to get a proper display. The 5081 is extremely heavy and deep. Not anything that you place on a normal desk.

A few years back snuci gave me a heads up on a Ebay auction for the Megapel board. Thanks!

From a 6151 which had a severe battery accident I have a Ungermann Bass ethernet board and the keyboard and mouse.

So this to be system is parts that has been picked up along the way and I hope that I can make an old workstation system running X11 on it.

BTW. Is it possible to run two screen on a RT? I still have that high res mono screen (and screen adapter) that came with the 6151. (The screen to the left in the picture above)
 

MattisLind

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Moved the streaming adapter from slot 3 to slot 7. Installed the Ungermann Bass adapter in slot 6 and installed the 5080 peripheral adapter (quad async board) into slot 3. All boards are now detected. So perhaps it is something with the 6157 streaming adapter and slot 3 that is not compatible?
 

snuci

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I've been searching for one for a few years now, I don't have one for my Megapel. I've just been using a BNC to VGA adapter and a flat panel monitor
I have been searching for something to connect to my Megapel adapter also. What does the cable wiring look like? Is is just Red, Red ground, Green, Green ground and Blue, Blue ground to the three Megapel outputs? I may have to fire mine up for the first time. I have the proper keyboard and mouse as well. I was just missing the monitor.
 

snuci

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Moved the streaming adapter from slot 3 to slot 7. Installed the Ungermann Bass adapter in slot 6 and installed the 5080 peripheral adapter (quad async board) into slot 3. All boards are now detected. So perhaps it is something with the 6157 streaming adapter and slot 3 that is not compatible?

Just an FYI. My streaming tape adapter was in slot 7. You can see what is where here if it helps at all: https://vintagecomputer.ca/ibm-pc-rt-6150/
 

MattisLind

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I am using a cable that take the DA15 3 coax connector (3W3?) and makes into 3 BNC. Then another cable that goes from 3 BNC into VGA.
Works Ok for testing purposes. But isn't very pretty. My monitor apparently can handle sync on green. I think many screens can. The 3W3 cable was used on quite many DEC workstations as well. DEC BC29H or BC29G I think the name is.
 

snuci

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I am using a cable that take the DA15 3 coax connector (3W3?) and makes into 3 BNC. Then another cable that goes from 3 BNC into VGA.
Works Ok for testing purposes. But isn't very pretty. My monitor apparently can handle sync on green. I think many screens can. The 3W3 cable was used on quite many DEC workstations as well. DEC BC29H or BC29G I think the name is.

Last question. Is the 3w3 Red Green Blue from the top of the adapter?
 

MattisLind

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Does this help?

FmWCdnVl.jpg


I started VRM floppy 1 and was able to see the partitioning of the hard drive.

zLtlizWl.jpg


So apparently the disk is readable. But it does not IPL automatically.

I tried the VRM command "vm" to IPL hd0 but it just gave me the text AIX 2.2.1 and then nothing happened.

Is there anyone with knowledge about various attributes and if that indicate if the minidisk is bootable?
 

snuci

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Thank you Mattis.

I have a stats code "22" no output on the megapel/VGA monitor and it's looking for a boot disk so I think we may have similar issues?

I'll make some diagnostic disks and see what's up.
Santo
 
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