Uncreative Labs

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I am thinking that perhaps my high density floppy drive controller is not working in my genuine IBM PC/XT because of an addressing conflict with the BASIC ROM. I was wondering if anyone knows of a way to remove BASIC. I am guessing that it is contained in either the U18 or U19 ROM, but I am not sure which one exactly. Has anyone ever tried it before?

Joined: 01 Oct 2004 Posts: 169 Location: behind you!

I'v never tried it but I don't think it can be done. I also don't think thats your problem (unless your trying to use the floppy while in rom basic). The system first tries to boot off media (floppy, hdd, ect). If it can't find an os it will then load rom basic (so if an os is found rom basic is never loaded).

Perhaps it's conflicting with something else in the system? Soundcard? Network card?

I seem to remember that msd can show irq and dma useage? Perhaps try that and see if you can track down the conflict.

if you don't have msd you can get it here

http://www.doc.ic.ac.uk/~ih/doc/par/doc/msd.html

Joined: 20 Nov 2004 Posts: 589 Location: Shandong, China

I tried removing ROM U19 which contains BASIC, but it prevented the system from booting. I guess that ROM must contain some other useful things too. I have no idea why my high density controller will boot in a Turbo XT but not in a real IBM. I have stripped the system down to it's bare minimums and it doesn't change anything. I'll have to run MSD or PCTOOLs and do a comparison between my XT systems.

Joined: 22 Oct 2005 Posts: 61 Location: sunny AZ

if you can find the IBM PC/XT Technical Reference, it has the bios code (assy language) listed, you could sort thru that and figure it out. right.

Guest

I think your asking for problems if you remove basic roms from a pc/xt.
the chip used in these machines is not the same as clones and substitution of a clone bios is not possible
but you can use a phoenix or other bios on a real AT or compatible.
and the at did have basic in the bios. ( but no setup)

most early pc/xt clones up to 8 mhz had many bios sockets and there was a basic set that worked in the xt clones. 10 mhz xt clones has, at most, 2 bios sockets. I know that this is not a direct answer but background.

at one company. the "guys" found an IBM XT with an UV eprom. and attempted top copy it, as the thought then was a " genuine ibm bios" was the best in compatibility. they were not sucessful. most xt's had masked buis' not uv eproms or eeproms( did not exist at that time)
the pc used 2332 not 2732 chips. tjhe xt use a chip SIMILAR to a 2764.

Joined: 21 Dec 2005 Posts: 66

Let's get to the root of the problem.

It's not an addressing problem with the BASIC ROM.

The BASIC ROM lives in the highest part of the memory map, and it is part of the system BIOS. No diskette controller is going to have an addressing conflict there, because every machine (clone or otherwise) has a ROM chip there. Period.

Clones don't have BASIC, but they still have the ROM there. There just isn't as much code in it. Often there is over code, like on later clones there is CMOS setup.

Also, at least for the PCjr the full ROM code isn't published in the tech ref. Part of it is copyrighted by MS (the BASIC interpreter), and doesn't appear for that reason.

It has to be something else causing your problem.