LSI-11 Simulator: which verison of RT-11 to use?

[RichCini]

All --

I am in the process of cleaning out my shop and was going through a box (one of several) of articles I ripped out of magazines. I found one from Circuit Cellar called "LSI-11 Simulator on a Personal Computer" by Bob Meister. I was also able to locate the code on-line (but it's hard to find), and with some tweaks, was able to get it running in DOS (running on Parallels on a Mac).

Anyway, it can take a diskette image as a command line parameter so I located a RX01 image of RT-11 5.4-SJ (ImageDisk format; converted to flat binary), but I'm not really sure this is the right version for a machine like that. The simulator has 32kw of memory and seems to report the right number of disk blocks and I get a "@@" prompt.

What version of RT-11 would the group recommend I try on a "machine" like this?

Thanks!
Rich

 

[kgober]

I took a quick peek at the source and it appears that the code emulates the LSI-11 itself (along with some RAM), as well as a Hazeltine 1510 console terminal, an RX11 floppy controller (able to handle up to 8 drives), LTC clock and a line printer. So, you will probably want a version of RT-11 that doesn't expect or require you to have a VT52 or VT100. RT-11 v3 might be a good option. RT-11 v4 would probably work as well if you take care not to run the KED or K52 editors (stick with the TECO-ish one).

 

[RichCini]

Excellent, thanks. Yes, that’s the configuration. I found a copy of what I think might be version 2. I might also have found a copy of v4. I haven’t been able to find a single-disk v3, but I found the 9-disk install set, so that might be good enough.

I plan on doing a partial rewrite of it as a Win32 console app using a VT100 emulation I have from my Altair32 project. The LTC and LP emulations will have to be reworked a bit, but I have some recyclable code for that too.

Rich

 

[RichCini]

I've tried several RT-11 versions today (v2 and v3, and one that looks like RXDP diagnostics) from both Dave Dunfield's archive (ImageDisk's converted to flat binary) and those from SIMH. Neither versions boot. For the bootstrap, I'm typing in the RXV11/RX01 bootstrap from page 11-16 of the RX01/RX02 Pocket Service Guide.

So, I think there's more work for me to do on this.

Thanks.
Rich

 

[RichCini]

From the code, it looks like a manual bootstrap isn't needed (code automatically loads the first sector) but maybe the disk needs a special device driver (Meister references creating a custom "PF" driver). So, this might be the issue. More work to do...

Something I just thought of...I know on my 11/23 I can't boot RT-11 if the LTC switch is on. I wonder...

 

[RichCini]

One important detail I missed when reading the code, that I didn't pick-up until re-reading the article, was that the author created a custom DX device driver for RT-11. None of the simulated floppy hardware device addresses are the same, so the default DX.SYS won't work. To add simulated memory, he crunched the memory mapped I/O area into 4kw (starting at 0170000 rather than 0160000).

So I guess I have four options: move memory around and see if the default DX.SYS will work; write a custom DX.SYS and make a new image using SIMH; continue to hunt down the author and see if he has any of the original files; give up and just use SIMH.

Thanks all!

Rich