[cctalk] Re: Booting from B: (Was: Getting QRST files onto
On 3/1/23 15:36, Fred Cisin via cctalk wrote:
> Chuck once told us that DRIVPARM can be coerced into working on some of
> the systemes that it won't work on, by inserting some Ctrl-A characters;
> DRIVPARM ^A^A^A /D:2 /F:2
>
>
> BTW, FORMAT, DRIVER.SYS uses the tracks and sectors that you specify
> FORMAT E: /T:80 /N:9
> ONLY to select WHICH ONE from the internal list. It WILL NOT let you
> change a format, such as
> FORMAT E: /T:77 /N:8 unless it already has that format somewhere in
> the internal list.
>
> https://retrocmp.de/fdd/8inch/drivparm.htm
> https://retrocmp.de/ms-kb/Q35766%20Supported%20Values%20for%20FORMAT%20:N%20and%20:T%20Switches.txt
>
> /F:3 was once 8" SD
> /F:4 was once 8: DD
> Any machines, other than SCP that still support those?
>
In PC DOS 3.2 and 3.3
When using PC DOS 3.2 or 3.3, DRIVPARM is undocumented but it can be
made to work using this trick. In CONFIG.SYS, type:
Normal DOS 4.0+ DRIVPARM set-up switches.
\/
DRIVPARM ^A^A^A {switches}
/\
Type Ctrl-A, not Shift-6 A. In MS-DOS's Edit, type Ctrl-P
then Ctrl-A (you will see a smiley face on the screen).
>From https://www.doomi.ch/undocumented-dos-commands/
--Chuck
[cctalk] Re: Booting from B: (Was: Getting QRST files onto
Chuck once told us that DRIVPARM can be coerced into working on some of the systemes that it won't work on, by inserting some Ctrl-A characters; DRIVPARM ^A^A^A /D:2 /F:2 BTW, FORMAT, DRIVER.SYS uses the tracks and sectors that you specify FORMAT E: /T:80 /N:9 ONLY to select WHICH ONE from the internal list. It WILL NOT let you change a format, such as FORMAT E: /T:77 /N:8 unless it already has that format somewhere in the internal list. https://retrocmp.de/fdd/8inch/drivparm.htm https://retrocmp.de/ms-kb/Q35766%20Supported%20Values%20for%20FORMAT%20:N%20and%20:T%20Switches.txt /F:3 was once 8" SD /F:4 was once 8: DD Any machines, other than SCP that still support those?
[cctalk] Re: PDP-8/A FPP8/A
Thats very interesting - a 10MHz 8 would have been quite something.
[cctalk] Re: Booting from B: (Was: Getting QRST files onto
Put a B sticker on the drive that boots, done. For a PC and any Tandon drive system there is a mechanical constraint to what drive is the boot drive. Jumpers and cable turn a generic tandon 100-x into the boot drive. It's not a ROM thing. The Osborne I *does* have a built-in ROM key-triggered A/B switch, DEC Robin too, Various others but not the PC BIOS. You could make the disk in drive A bootable, put a minimum OS on it, add a line ATTRIB B:; and PATH B; to an autorxec.bat that allows the computer to.pull most DOS files off the B drive, so you can have max space on the A drive for another program. There are books .from the period full of DOS tricks, but the OS level is not the hardware level. Blah blah Bill On Wed, Mar 1, 2023, 3:26 AM Steve Lewis via cctalk wrote: > Can't help with booting DOS to a B: drive. But, in case of interest - I do > keep the IBM PC 5150 notes here: > Specifically as might be related here, I have some notes on using 4 disk > drives: > > https://voidstar.blog/5150-setting-up-floppy-disk-controller/ > > And main point is, the DOS DRIVER.SYS might let you control the disk drive > letters in a way that > might help in some way. I think it was available pretty early on -- if not > PC-DOS 1.0, at least PC-DOS 2.0. > > DEVICE=\DOS\DRIVER.SYS /d:2 /t:80 /s:9 > DEVICE=\DOS\DRIVER.SYS /d:3 /t:80 /s:9 > > There is also a SUBST command. Can't remember if SUBST lets you override > an existing letter -- I think is probably does. > But if you don't have a B: drive at all, you can do something like: > SUBST B: C:\UTILS > Then the whole B: drive gets substitutes to that given folder. > > > My more main IBM PC 5150 notes are here: > > https://voidstar.blog/ibm-pc-5150-notes/ > > > > On Sun, Feb 26, 2023 at 5:55 PM Fred Cisin via cctalk < > cctalk@classiccmp.org> > wrote: > > > > Which versions of DOS let you boot off B: ? > > > > CORRECTION: > > Although the default of DOS used to be A: then first HDD (usually C:), it > > is the computer firmware, not DOS that decides that. > > > > The assumption that C: is the HDD can be annoying. I used to use PCs with > > four floppies. If jumpered properly, the HDD was E:. > > > > > > Many "modern" PCs, within the "CMOS" setup, have provision for changing > > the boot sequence. Mostly, in order to default to booting from HDD, > > rather than floppy, but also for CD or USB boot. > > I do not know of any that permit selecting floppy B: for boot, but there > > could exist some with that option, . . . > > > > On a PC with a single physical floppy, asking for any command with B: > will > > trigger a prompt to put the B: disk in drive A:, and have a phantom B: > > that shares the physical drive with A: > > > > Swapping A: and B: is, of course, trivial to do with hardware, and/or > > messing with the cable. (pin 10 of the cable [at the FDC] is A: and 12 > is > > B:, but the usual supplied cables are twisted and missing pins so that > > every drive, on the drive itself is jumpered as if it were B:). An > > untwisted cable, with switch[es] would be one way. > > > > -- > > Grumpy Ol' Fred ci...@xenosoft.com > > >
[cctalk] Re: Booting from B: (Was: Getting QRST files onto
Can't help with booting DOS to a B: drive. But, in case of interest - I do keep the IBM PC 5150 notes here: Specifically as might be related here, I have some notes on using 4 disk drives: https://voidstar.blog/5150-setting-up-floppy-disk-controller/ And main point is, the DOS DRIVER.SYS might let you control the disk drive letters in a way that might help in some way. I think it was available pretty early on -- if not PC-DOS 1.0, at least PC-DOS 2.0. DEVICE=\DOS\DRIVER.SYS /d:2 /t:80 /s:9 DEVICE=\DOS\DRIVER.SYS /d:3 /t:80 /s:9 There is also a SUBST command. Can't remember if SUBST lets you override an existing letter -- I think is probably does. But if you don't have a B: drive at all, you can do something like: SUBST B: C:\UTILS Then the whole B: drive gets substitutes to that given folder. My more main IBM PC 5150 notes are here: https://voidstar.blog/ibm-pc-5150-notes/ On Sun, Feb 26, 2023 at 5:55 PM Fred Cisin via cctalk wrote: > > Which versions of DOS let you boot off B: ? > > CORRECTION: > Although the default of DOS used to be A: then first HDD (usually C:), it > is the computer firmware, not DOS that decides that. > > The assumption that C: is the HDD can be annoying. I used to use PCs with > four floppies. If jumpered properly, the HDD was E:. > > > Many "modern" PCs, within the "CMOS" setup, have provision for changing > the boot sequence. Mostly, in order to default to booting from HDD, > rather than floppy, but also for CD or USB boot. > I do not know of any that permit selecting floppy B: for boot, but there > could exist some with that option, . . . > > On a PC with a single physical floppy, asking for any command with B: will > trigger a prompt to put the B: disk in drive A:, and have a phantom B: > that shares the physical drive with A: > > Swapping A: and B: is, of course, trivial to do with hardware, and/or > messing with the cable. (pin 10 of the cable [at the FDC] is A: and 12 is > B:, but the usual supplied cables are twisted and missing pins so that > every drive, on the drive itself is jumpered as if it were B:). An > untwisted cable, with switch[es] would be one way. > > -- > Grumpy Ol' Fred ci...@xenosoft.com >
