Help with bootstrap code

[new_castle_j]

Hello all, I'm looking for some help disassembling a bootstrap program. This is for an XT clone that goes into an S-100 bus computer. The board first boots to TurboDOS (CP/M-86 compatible) then by executing the BOOTPC.CMD (attached), it is supposed to boot into PC-DOS by reading in another file called BOOTFILE.DSK which is an image of a PC-DOS boot floppy. When I execute BOOTPC.CMD I get an error "Can't open download file." I haven't been able to figure out why this error happens and am hoping that some clue lies in the BOOTPC.CMD file. The board has an 80188 processor, but I suspect an 8086 disassembler would do the trick. Anyone willing to run this little file thru a disassembler?
Many Thanks

 

[krebizfan]

Well, it crashed IDA Freeware instead of being disassembled so it is an interesting file.

 

[Chuck(G)]

Are you sure that this is an S100 computer? I see a search for "POPPY" in a low memory area.

Are you sure that this didn't come from a Durango Poppy? (A 186/286 system)

FWIW, entry jumps are at 0180H offset from the start.

 

[new_castle_j]

Yeah, I'm sure it's an S-100 Poppy, the manual can be seen here:
http://bitsavers.org/pdf/charterInformationCorp/

I've been messing with this board for quite some time, but I think this is the final hurdle to getting PC-DOS running on it.

 

[Chuck(G)]

Interesting that Charter claims the Poppy trademark. See the ad here.

The code doesn't seem to be too difficult. I'll run an Ida Pro disassembly if you'd like.

 

[new_castle_j]

Thank you Chuck, yes I would appreciate a disassembly.

When I first got this board I too was puzzled about how the name Poppy was being used by both companies. I believe they both had the same subliminal message in mind, a minor dig at IBM's marketing with the Charlie Chaplin character and the fact that he carried a Rose around.

 

[Chuck(G)]

I really don't remember--it was a name (at Durango) dreamt up by the marketing folks. Heck, I've still got 5.25" floppies that are "Poppy" branded. Note that we started on this thing in 1981-82--the 5150 had just barely come out and the 80186 was still in pre-release stepping, bugs and all. The 80286 wasn't stable enough in real mode, let alone protected. We initially released the system with only the 80186 socket populated--running at a screaming 6 MHz.

At any rate, I've attached a quick run at disassembly. Note that you'll have better luck looking at the binary by ignoring the first 180h bytes and loading the result at 100h. Seems to be a standard CP/M-86 executable. You can probably get a file you can manipulate yourself with the free version of IDA by clipping off the first 180H bytes of this file and renaming it to BOOTPC.COM.

Looks to be pretty straightforward, eventually loading the named file at 0000:7C00 and jumping to it, just like a regular PC.

 

[new_castle_j]

Thank you for the disassembly Chuck, and for the tutorial on why I had so much trouble trying to disassemble myself.