• Please review our updated Terms and Rules here
  • Exhibitor application for VCF West 2022 is now open! If you are interested in exhibiting, please fill out the form here.
  • Here are the results of the VCF East 2022 Post Event Survey: Survey Results

How to create FreHD auto-boot image (for model 4)?

vldmrrr

Experienced Member
Joined
Aug 20, 2016
Messages
131
Location
IA, USA
I created a new image with `vhdutl`, partitioned it with `rshard6` and formatted with `rsform6`, then I copied with `backup` the first partition of auto-boot `lsdos` image from Ian's archive. My image is not included in FreHD boot menu. I tried renaming it to `lsdos` while renaming original to something else. That did not make my image appear in menu, but Ian's image was included under its new name.

So the question is: what makes the image recognizable by frehd boot rom?
 

Gazza

Experienced Member
Joined
Jun 27, 2013
Messages
148
Location
Sydney, OZ
I seem to remember sumptin' about changing byte 08&H of the header to '01'
Give that a try.
 

Jenz

Experienced Member
Joined
Mar 14, 2019
Messages
85
Bash:
printf '\x01\' | dd of=image_file bs=1 seek=8 count=1 conv=notrunc
Byte 0x0B in the header should be checked for the disk format defined in 'fred.inc':
Code:
;; Reed header  http://www.trs-80emulators.com/hdv1-format/
;;
;; byte 0-1
REED_MAGIC0     equ 56h
REED_MAGIC1     equ 0cbh
;; byte 8  : flag #2 -> bit 0 = auto-boot
;; byte 11 : disk format.
;;    0 = LDOS 6.3.1
;;    1 = LDOS 5.3.1
;;    2 = CPM
;;
REED_FLAG       equ 08h
REED_OS         equ 0Bh
OS_LDOS631      equ 0h
OS_LDOS531      equ 1h
OS_CPM          equ 2h
OS_NEWDOS25     equ 3h
OS_M1LDOS531    equ 4h
OS_M1NEWDOS25   equ 5h
MAX_OS          equ 6h
 

vldmrrr

Experienced Member
Joined
Aug 20, 2016
Messages
131
Location
IA, USA
Bash:
printf '\x01\' | dd of=image_file bs=1 seek=8 count=1 conv=notrunc
That worked well for enabling inclusion of the image to boot menu, thank you!

Now I tried to apply this to the model 4p auto-boot image in Ian's archive. I like the image because it has larger size partitions. But although it does appear as a choice on boot menu, booting from it results in randoms ASCII art on the screen and never end in working system. I know the image is good as it does boot in trs80gp emulation of model 4p.

What is it that makes the difference between 4 and 4p with respect to booting under frehd? I thought all custom boot code is in modded ROM and in file frehd.rom, but apparently there is more to it - in image itself.
 

Gazza

Experienced Member
Joined
Jun 27, 2013
Messages
148
Location
Sydney, OZ
Both of my 4Ps are in storage ATM and most of my TRS80 stuff is on a dead desktop so I'm going by my (fading) memory.
That 4P image on Ian's site was built for a stock 4P and predates the FreHD.Rom but it will work on a 4P with the modified rom.
It has modified sys files and calls on the 4P rom so I highly doubt that it would work on a Model 4
 

Patrick.B (TTR)

Experienced Member
Joined
May 11, 2011
Messages
344
Location
Houston, Texas, USA
There are two types of images.
The one that boots from a floppy diskette and one that autoboots from the "modified" Rom boot and no they are not interchangeable.
which s one are you speaking of ?
 

Jenz

Experienced Member
Joined
Mar 14, 2019
Messages
85
The original ROM of the 4P could already boot from hard disk (What did Frank Durda Say About the Model 4):
One thing that I did on the 4P ROM that was unpopular was that the hard disk boot code would try to boot off a hard disk drive, even when it couldn’t. At the time, the method for booting directly off the hard disk drive was known and it was just question of doing it.
For LS-DOS 6.3.1 the attached patches are needed to boot directly from a hard disk. This is for the Model 4P only, so the "auto-boot" flag is not necessary (and not set in the header of the 'hard4-0' image) for FreHD to boot the 4P auto-boot image.
 

Attachments

  • hdbt2.zip
    9.1 KB · Views: 2

vldmrrr

Experienced Member
Joined
Aug 20, 2016
Messages
131
Location
IA, USA
I was trying to create larger auto-boot frehd image for model 4, larger than lsdos m4 image in Ian's archive. The 4p image from there is larger, so I tried to use that as starting point. Setting auto-boot flag in header of that image does not make that 4p image bootable on m4, it crashes.

Other things I tried was to copy everything with `backup` from 1st partition of the smaller m4 auto-boot image onto 1st partition of m4p image, and overwriting the 1st partition of m4p image with with exact replica of m4 image using `dd`. In both case auto-booting the created image results in `No system` message.

Is there some loader code on the image itself that frehd loads on auto-boot?
 

Jenz

Experienced Member
Joined
Mar 14, 2019
Messages
85
Setting auto-boot flag in header of that image does not make that 4p image bootable on m4, it crashes.
As Gazza already pointed out: LS-DOS 6.3 in the 4P auto-boot image has modified SYS files (patches in ZIP archive above) for the Model 4P only!
This hard disk image will simply NOT work with the Model 4, regardless of the "auto-boot" flag in the header ...
 
Last edited:
Top