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Paul correctly notes that with Unibus, you can put the memory "wherever you like" physically and it will "work" assuming you configure it correctly, with one major caveat. Read the manuals carefully! The caveat is that for "fast" semiconductor memory on the 11/45, there is a dedicated set of...

That is what I would have thought, and while the UCxx manual (on bitsavers) doesn't outright say that the UC07-III will not work in a QBUS PDP-11, it implies that there's some difference. On page 4-3, it seems to imply that the difference could be mostly physical, stating The manual is pretty...

I have three of these kind of boards, of both versions. 1. I have a UC18, a dual-ported UNIBUS version in my PDP-11/34. It works great with a SCSI2SD. I usually run RT-11, though have also played with RSTS/E. I keep meaning to attach a SCSI tape drive to the other port, but haven't gotten to...

I concur! I've done this approach many times and even recall seeing it detailed in a DEC maintenance manual somewhere. I only got in trouble once, but that was because I stole my dedicated side cutters from our bathroom without informing the other inhabitants of my house... the cutters were...

Indeed. I don't know about the MicroVAX 2000 specifically but NetBSD doesn't support all the early DSSI SCSI chipsets. I've got a VAXStation 3520, the SCSI for which NetBSD does not support, even though the CPU is supported just fine. OpenBSD does support the DSSI SCSI, so that is what I'm...

True, NetBSD does not support the DSSI disks. But if you don't mind an older version of OpenBSD, that might work instead. Even though the driver codebases between NetBSD and OpenBSD are similar, they are not identical. See: https://www.openbsd.org/vax.html It looks like OpenBSD 5.8 supports...

If you don't mind the lack of sign, you can just wire the meter for -15V "backwards". My PDP-11/45 came to me without a power supply (a blessing in disguise, I suppose), so I built a switcher for it. I got several of these meters, so that all the voltages read out on a single panel: ... and...

MIT apparently made a similar board for UNIBUS PDP-11s, and called it an MB11. For "Memory Break", though perhaps as a nod to the PDP-8 MARS panel, the device is referred to as a "MAR" in other places. Instead of halting the processor on a specified address, the MB11 triggers an interrupt...

An update on SITS archaeology, for those interested... I was wondering how SITS allocates memory across processes, and how the memory-resident RUG debugger works. The documentation for RUG states that it is a swapping debugger, and will load/unload itself as needed from a protected copy on...

Ah! You solved a mystery I forgot about. As a child, my family had an Atari 800XL. I distinctly recall the sound of loading things from floppy, but never connected the audio chip with disk accesses. At the time, I thought the sounds were "added for effect" rather than being a "side effect"...

Well, if an FP11-B (like Dave has) were to be made, then I would be interested! I have a KB11-A, which takes such a thing. The module utilization chart on my box says: FXP: M8113 FRM: M8112 FRL: M8115 FRH: M8114 Regards, Michael

Greetings! Good luck in your search. I'm also a PDP-11/45 owner here... and I've been looking for an FP11 for several decades...

At the risk of becoming a PDP-11 audio jockey... A request! Here's a quick and easy snippet. Compiling a hello world C program on Unix v6: $ cc hello.c Put on some stereo headphones! Compilation is mostly on one ear, while linking is mostly on the other. Not sure why that is, exactly...

Please share what you find if you do! One my students who heard my recordings asked if different PDP-11 CPUs running similar OS's, but perhaps with different devices, might be noticeably different. Thanks! I definitely recall that TNG episode, but hadn't made the connection to the sound...

I've often thought about the experiential difference between running emulators and "actual" hardware. Surely the emulator is easier to configure and can give more debugging information, but the actual machine has "presence". Right? It's big, makes noise, keeps my basement warm during the...

Greetings! I'd like to announce a project to restore the MIT Small Incompatible Timesharing System (SITS), which is a port (of sorts) to the PDP-11 of the venerable ITS for PDP-10. Historically, SITS was the development platform for the original MIT LOGO environment. You can read some history...

That's my impression now too. So my question is whether there's an (undocumented) way to get the Emulex to read something else for you instead of the first block of the boot SCSI device. There may or may not be, depending on exactly how this boot "routine" was written. I spent several hours...

Yup. I can spot Intel assembly at a distance :-P I just pulled the UC07 board from my 11/23 to confirm. Same CPU, same code rev. I'm now poring over the binary dump you posted... hopefully I'll find something interesting! I've already found the messages for the Disk Firmware Resident...

@AK6DN, Thanks for the ROM listings! Assuming they are for what I think they're for (the CPU living on the UCxx board, which is an Intel machine of some sort), that is just what is needed to dig for undocumented features. The page from the Emulex manual you attached is precisely what I've...

Reporting back... The hypothesis to be tested is that "the Emulex controller boot shortcut process only loads the boot block from DU0:, but can pass unit numbers (to a compatible bootstrap) via R0". Evidence in favor: Since the Emulex boot block load sequence is done entirely while the CPU is...