20 Jan
2025
20 Jan
'25
4:44 p.m.
For those not on the Discord (it's great) here is my thought:
Since the 11/20 has two serial ports, set the second to 176500/300
address/vector and hook it to a PC running a TU58 emulator. Then toggle
in a TU58 bootstrap, and boot up RT11 on the emulated TU58.
Then pop in a floppy and do a format, then copy over all the files with
a copy/sys du0:*.* dy0: followed by a copy/boot dy0:rt11fb.sys dy0: and
boot up off the floppy.
Much simpler than trying to transfer images and whatnot.
C
On 1/20/2025 7:28 PM, Wayne S via cctalk wrote:
Martin, sent you a Digital Equipment Corp discord
invite.
You should br able yo get zll you questions answered there.
Sent from my iPhone
> 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.