• Please review our updated Terms and Rules here

DOS in the 1000HX

G

Great Hierophant

Veteran Member
Joined
Mar 22, 2006
Messages
1,928
Location
Massachusetts, USA
Tandy 1000 HX came with one 3.5" drive standard and came with Tandy MS-DOS 2.11.26 loaded in ROM and on a non-bootable disk. In the Tandy 1000 line, the other machines in the pre TL/SL line came with the following DOS versions:

1000 - 2.11.22
EX - 2.11.24
SX - 3.2.0
TX - 3.2.21


The SX and the TX obviously support the 3.5" drive because they use DOS 3.2, which was the official first version with that support. If you bought an EX, with room for only one 5.25" floppy drive, you could attach an external 5.25" or 3.5" drive, with the latter requiring DOS 3.2 to support 80 tracks. Ditto for the original 1000, except it would need an internal upgrade.

For the HX, the machine supported three floppy drives. There is official BIOS support for the 3.5" drive. The setup program required the user to specify which type of drive each was, and a drive could be either type. It had room for two 3.5" drives inside the machine an an external 5.25" or 3.5" drive. It could boot from either the first internal or the external drive. The DOS-in-ROM contained only what was necessary to boot to DOS and the menu (64KB used in E000-EFFF).

DOS 2-3 would assign drive letters to floppy drives first, then hard drives. If you had more than two floppy drives, then the third would be C:, the fourth would be D:, then the hard drives would have letters assigned. In a stock HX with only one 3.5" drive, it is drive A and the ROM is drive C. If you add a second internal 3.5" drive, it becomes drive B. If you add a external, third, drive, it becomes drive C and the ROM is now drive D.

The bootable part of DOS 3.2 does not fit into 64KB, never mind the menu, so I believe that Tandy used the 2.11 and added 720K/80 track functionality where needed. This had to included patches to FORMAT, DISKCOPY, BASICA, BASIC, DISKCOMP, CHKDSK and others external programs. This saved money and PCB space on extra ROM and paging functionality. (The BIOS uses 64KB from F000-FFFF).
 
<snip>Do not block quote an entire post to add one line</snip>

Never was a HX fan, jumped right in with the SX. Good job on the above!
 
Last edited by a moderator:
Great Hierophant said:
This had to included patches to FORMAT, DISKCOPY, BASICA, BASIC, DISKCOMP, CHKDSK and others external programs.
Click to expand...

Uhm, no it didn't... DOS 3 may have been the first to automatically recognize a 3.5" drive, but with the DRIVEPARM config.sys option ANY DOS 2.x could support floppies up to just under 16 megabytes in size! (as long as the MFM data rate was 250kbps or lower) I always figured they had the ROM DOS just run DRIVEPARM -- whcih is why booting from a non-tandy DOS 2.11 it 'loses' the floppy halfway though the boot process. I've run 1.2 megabyte 8" shugart 850's off even the EX and original 1000 without problems just by adding driveparm to the config.sys. You get the right values in the drive tables, you don't need to patch anything else!

Literally the only 'patch' needed to use a 720k 3.5" floppy on DOS 2.x is to get the OS booted and add an entry to the drive parameters table. Every other program will pick up that change automatically. (assuming it uses int 21h for disk access)

Though I'm used to forum posts where people ask questions -- you seem to be posting like this was a wiki or your own personal blog or something.
 
DRIVPARM was introduced in MS-DOS 3.2. It was first documented in DOS 4.0. PC-DOS 3.2 and 3.3 require some special handling of the CONFIG.SYS line; apparently IBM didn't want it to be accessible by the average user.

DOS 2.x can be fun to fool with if you're unfamiliar with it. Two CONFIG.SYS commands SWITCHAR and AVAILDEV can make your system look more like Unix; but most third-party programs don't bother to ask for the switch character; they just assume it will be /.

But on DOS 2.x, you're stuck with DRIVER.SYS, AFAIK.
 
According to Tandy's MS-DOS reference, which covers 2.11 and 3.2, DRIVPARM and DRIVER.SYS were only included in 3.2. I would suggest that if the BIOS did not support the disk parameters, DOS 2.x won't work.
 
That's REALLY strange you guys are saying that -- since the manual for the HX lists DRIVPARM as a valid config.sys option... Appendix B, Page 324... the manual covers both 2.11 and 3.2, and lists it as available in both...

and I've USED IT booting from the rom and loading drivers/config from floppy so... (how else do you get 720k and 360k floppies working from rom simultaneously?)

Great Hierophant said:
According to Tandy's MS-DOS reference, which covers 2.11 and 3.2, DRIVPARM and DRIVER.SYS were only included in 3.2. I would suggest that if the BIOS did not support the disk parameters, DOS 2.x won't work.
Click to expand...
Really weird as if I'm looking at the same book -- I find no reference of it not being available in 2.11 -- Cat. No. 25-1508 right?

Wonder if for the HX they just back-ported that to the HX ROM from DOS 3.x and it's just not avail in OTHER 2.11 implementations.

-- edit --

I just booted my HX up, used driveparm with the external floppy to tell it that it's 360k... worked JUST FINE. MS-DOS 2.11.26 in ROM, loading config.sys off the 720k drive A:
 
Last edited:
I have the manual in question, the Tandy 1000 MS-DOS Reference Manual, Cat. No. 25-1508, from 1986. It was written before the HX and TX's time. Page 325 has a 3.2 symbol next to DRIVPARM and ditto for DRIVER.SYS on page 332.

On the ROM disk, there are only six files : IO.SYS, MSDOS.SYS, COMMAND.COM, AUTOEXEC.BAT, P.COM and INTLDRVR.COM. Having looked into the ROM, the available CONFIG.SYS commands do not include DRIVPARM, FCBS or LASTDRIVE, all official 3.x additions. On the other hand, COUNTRY is there, but the book says it is a 3.2 addition. There are also two other undocumented commands, SWITCHAR and AVAILDEV. Tandy DOS 3.2 also contains STACK, undocumented.

All drives should be setup with the HX setup program.

I would suggest that the HX is AT-like in its floppy drive configurations. The AT originally could be configured with 1.2MB or 360KB drives, and drive setup would be accomplished in the CMOS battery backed RAM. DOS 3.x and above would look there to see what drives it had in the system. DOS 2.x and below were designed for the IBM PC/XT, which only knew about 5.25" drives, as did the earlier 1000s. The HX has EEPROM in which it stores the drive configurations. I would suggest that Tandy took that portion of DOS 3.x which looked to CMOS and added it to their DOS.

deathshadow said:
That's REALLY strange you guys are saying that -- since the manual for the HX lists DRIVPARM as a valid config.sys option... Appendix B, Page 324... the manual covers both 2.11 and 3.2, and lists it as available in both...

and I've USED IT booting from the rom and loading drivers/config from floppy so... (how else do you get 720k and 360k floppies working from rom simultaneously?)


Really weird as if I'm looking at the same book -- I find no reference of it not being available in 2.11 -- Cat. No. 25-1508 right?

Wonder if for the HX they just back-ported that to the HX ROM from DOS 3.x and it's just not avail in OTHER 2.11 implementations.

-- edit --

I just booted my HX up, used driveparm with the external floppy to tell it that it's 360k... worked JUST FINE. MS-DOS 2.11.26 in ROM, loading config.sys off the 720k drive A:
Click to expand...
 
Great Hierophant said:
I have the manual in question, the Tandy 1000 MS-DOS Reference Manual, Cat. No. 25-1508, from 1986. It was written before the HX and TX's time. Page 325 has a 3.2 symbol next to DRIVPARM and ditto for DRIVER.SYS on page 332.
Click to expand...

3.2 symbol? I don't seem to have those in mine. (NOT even sure what you are referring to)
 
. . . on page 325 of 25-1508 directly below DRIVPARM, is a small 5.25 floppy like icon with "3.2" in the center - at least in book.
 
Great Hierophant said:
Tandy 1000 HX came with one 3.5" drive standard and came with Tandy MS-DOS 2.11.26 loaded in ROM and on a non-bootable disk. In the Tandy 1000 line, the other machines in the pre TL/SL line came with the following DOS versions:

1000 - 2.11.22
EX - 2.11.24
SX - 3.2.0
TX - 3.2.21
Click to expand...

At least the EX didn't come with DOS on ROM. Kind of a shame. I don't suppose there's a socket in the machine where you could add a ROM?

If you bought an EX, with room for only one 5.25" floppy drive, you could attach an external 5.25" or 3.5" drive, with the latter requiring DOS 3.2 to support 80 tracks. Ditto for the original 1000, except it would need an internal upgrade.
Click to expand...

Can you adapt an internal 3.5" for external use on a Tandy?
 
I don't see why not. There's nothing really special about the Tandy other than it has power supplied over the data ribbon cable. You could break that out on the floppy side.
 
Hatta said:
Can you adapt an internal 3.5" for external use on a Tandy?
Click to expand...
You can -- but beware you can only use it as a 720k drive; the floppy controller doesn't support the higher data rate needed for either 5.25" 1.2 meg or 3.5" 1.44 meg disks.
 
You must log in or register to reply here.
Back
Top