AT&T 3B1 / 7300 / UNIX PC: Boot sequence from floppy

[SPC]

Great news, Philip. Perhaps finally I could have a replacement for my 3B1
and my 3B2/400 (It's a joke, I like a lot the old stuff).

I have a great lot of manuals of the thing, mostly for the 3B2, but casually
(or not) appeared in past days 3th and 4th some manuals about the matter in
http://www.bitsavers.org/pdf/att/3b1/

Good luck and Greetings
-----
Sergio
http://es.linkedin.com/in/sergiopedraja
twitter: @sergio_pedraja

2010/12/6 Philip Pemberton <philpem at philpem.me.uk>

> Hi guys,
>
> I've got my 3B1 emulator "mostly working" in that it runs the Boot PROM,
> sees the floppy disc in the drive, and proceeds to boot from it, getting
> as far as the Loader.
>
> When it gets to the Loader, I get the following display:
>
> AT&T UNIX(tm) pc
> Loader version 3.51
> Copyright (c) 1985, 1986
> AT&T
> All Rights Reserved
>
> Searching floppy disk...
> ####
>
> Searching hard disk...
>
>
> ... and it stops there. I can tell from the emulator log that it's
> trying to get the hard drive controller to read CHS 0:0:0 and DMA the
> data into RAM at 0x77830, but because the HDC isn't implemented, it
> locks.
>
> What I expected was for the Loader to pick up the boot files on the
> Diags disk, boot from that, and ignore the HDD. Does anyone know what
> "typical boot behaviour" is for a 3B1, 7300 or UNIX PC, when booted from
> the Diagnostics floppy (Foundation Set, disk 1) ?
>
> This is a bit of a head-scratcher -- I'm trying to figure out if there's
> a problem with my FDC driver (wouldn't be the first one) or the
> DMA/interrupt controller, or if the Loader really needs a hard drive
> controller (or a really good fake) to boot the system.
>
> I'd also really like to know why the DMA controller has two separate
> direction control bits -- DMAR/W- and IDMAR/W-... this seems downright
> silly, though in keeping with the rest of the TechRef. My "annotated
> edition" corrects about a dozen minor and major errors in the register
> set descriptions, and adds a bunch of informational sticky-notes and
> scribbly comments to reinforce certain points. Ewwww...
>
> If anyone's interested in playing with my emulator -- go to
> <http://www.philpem.me.uk/code/3b1emu/>. Hit the link under "Mercurial
> repository", then ".tar.bz2" to get a Tarball of the sources. Untar it.
> Grab the boot PROMs, and put them in a directory called 'roms' as
> '14c.rom' and '15c.rom'. Use IMDU (Imagedisk utility) on a DOS PC (or
> inside Dosbox) to convert the Foundation Set disks from IMDs to binary
> files, then copy the first Foundation disk (Diagnostics) as 'discim'.
> Compile (you'll need libsdl, aka the Simple DirectMedia Layer) and run.
>
> I know the code is a mess, patches to rectify this (or any of the other
> millions of bugs) would be almost certainly be accepted :)
>
> There's also no keyboard or mouse emulation yet, just the CPU, video,
> RAM, ROM and a basic memory mapper and DMA emulation. As for Ethernet
> emulation... that's on the "maybe later" list, right after "learn how to
> send and receive Raw Ethernet frames on Linux".
>
> Thanks,
> --
> Phil.
> philpem at philpem.me.uk
> http://www.philpem.me.uk/
>
>