[cctalk] Re: Looking for bootable floppy image for a PDP11/20

On Jan 20, 2025, at 16:04, Martin Eberhard via cctalk <cctalk(a)classiccmp.org> wrote: I looked at those images on Bitsavers. As far I understand, an RX211 controller can't boot a disk with an RX11 bootstrap program. The RX211 uses DMA to transfer the data, while the RX11 requires software to transfer the data in a loop, one word at a time. Additionally, RT11 (or any other OS) has to be configured for the RX211, differently than for the RX11, for the same reason. (A good driver would look at the status register and detect whether it is an RX11 or RX211, and adjust accordingly. I don't know if DEC did this or not.) Every single-density image that I could find either does not have a boot loader (Track 1, sector 1) or it has a boot loader for the RX11 controller. I have not yet found a disk image (single-density or double-density) for an RX211 that is bootable. This would require both the boot sector to be for the RX211, as well as the RT11 image itself, configured for an RX211 drive. (Or configured to detect the drive type and do the right thing...) I'm kind of new the the DEC world (aside from learning PDP11 assembly language in collage...) Any pointers, advice, DISK IMAGES, etc. is greatly appreciated :-) Thanks, Martin E.