From: kr-lund@nogarbage.online.no
Frank Durda IV wrote:
> Kelly Leavitt wrote:
> : OK, does the Model 2000 have BIOS in ROM, or does it have a bootloader
> : that loads the BIOS from the boot diskette?
>
> It has a boot loader in ROM. The equivalent of a BIOS call layer is
> loaded from the boot diskette. The actual physical ROM is tiny, far too
> small for a PC-compatible BIOS.
>
>
> : Anybody have any references for this other than "that's what I was
> : told"?
>
> Yeah, I wrote some of the code in the 2000 BIOS, and didn't enjoy most
> of it, mainly because I got sucked involuntarily into the project when
> seven of the eight system programmers on the project quit. Being one
> if not the most recent hires into the Systems department, I didn't
> have adequate traction to prevent the group transfer.
>
> The original task was to write the BIOS calls that hadn't been written at
> all (those BIOS functions were simply not present in the DOS releases that
> went with first months worth of system shipments), but this quickly grew
> into having to fix bugs that the others left behind.
>
> The video piece was the most incomplete when I got there, and the video
> hardware was the least PC compatible of anything on the 2000.
> To make the task more challenging, I had to learn the 80186 instruction
> set and its evil segment register scheme*. Then to troubleshoot
> third-party apps that didn't work, I had to also learn the 8086/8088
> instruction set in fine detail, so as to discover the subtle
> differences between it and the 80186 that were breaking these existing
> applications (SuperCalc 4, Lumena and Lotus spring to mind as
> "important" packages that broke on the 2000), and I was supposed to
> somehow compensate for these problems within the application. Plus,
> I had to learn the wacky Intel "Blue Box" cross-assembler, linker and
> emulator system pretty much on my own - everyone else who knew much
> about the OS writing side of using this thing had quit. Fortunately
> some of the application writers also used the box and helped me get
> going, but then they sucked up lots of hours I needed using the box on
> their development projects. We only had one Intellic (I think that was
> the name of the blue box) and we could have used two or three. The
> emulator cost a fortune and was extremely finicky. One day management
> decided to move where it was located (because it was too close to the
> elevator lobby) and it didn't work for a week or more after that.
>
> I eventually had to completely re-write a number of existing BIOS or
> pseudo-BIOS algorithms that didn't work right or ran "too slowly".
> Most of this performance problem centered on the 2000s' multi-plane
> video scheme (BAD IDEA, NO BISCUIT), so the BASIC pseudo-BIOS function
> "PAINT" had horrific performance on the 2000 when coded in a way
> that probably had worked well on a CGA video card. Of course, the
> Model 2000 store demo (which was written in BASIC an was already in
> the field) used PAINT extensively.
>
> The monochrome video side actually had a lot of neat capabilities,
> virtually none of which were made available because the IBM BIOS
> didn't have them. A few Tandy-specific extensions were done, but
> with so many pieces of the BIOS not written at all or not working,
> the extra features largely got lost and those that did work don't
> seem to have been used in any popular applications. Reason: those
> features weren't available on the IBM and the software vendors
> didn't want to have to code and manufacture two versions.
>
> Meanwhile, management did their part to maintain my morale by constantly
> yelling to hurry up and complaining that I wasn't working on this
> 90+ hours a week. (Tandy defintely did not pay overtime.)
>
> I probably assembled, linked and relinked that BIOS layer several hundred
> times over the six or seven month period while trying to get all of the
> documented BIOS calls actually implemented and then running fast enough
> to make people stop whining as much about the machine.
>
> It really was a no-win situation, because graphics were one of its
> saving points that were constantly touted for the 2000, but the machine
> would never be fast in the graphics department. The color graphics
> hardware design on the 2000 conspired against fast graphic operations for
> all but a few area filling tasks, which could be done extremely fast but
> also had enough highly visible video flicker artifacts that those
> techniques were objected to and could not be used in most situations.
>
> About five months along into this nightmare, Tandy obtained development
> software from somewhere that would run on the 2000 themselves (I don't
> believe it was MASM as I recall MASM couldn't generate the needed
> output) and could dispense with the Intel blue box for 80186
> assembly/linking, but I only worked on the 2000 for another couple of
> months. Work on the 2000 BIOS ended at the start of August 1984. I was
> the last one doing anything to the machine BIOS/OS and had been since
> January or February of 1984.
>
> I then went out to SCO at Santa Cruz and wrote the serial port bootstrap
> loader for XENIX-186 during the week of August 5th, 1984 (that date
> is permanently recorded in my memory). (The 2000s incompatible disk
> controller meant they had to download a XENIX kernel via the serial port
> until they got custom-written floppy disk controller drivers working.)
>
> After I returned to Fort Worth a few weeks later, I got sucked into
> working simmering problems that had finally boiled up to crisis level
> on the Model 16 XENIX OS. I never returned to doing work for the 2000,
> other than the occasional consultation.
>
>
> * Having been introduced at the 80186 and 80286 points in the Intel line,
> it helped solidify my dislike for Intel, who just seemed to have
> everything backwards, but back then backwards was apparently okay if
> IBM bought it. At least Intel had a real stack pointer, something most
> of IBMs mainframes of the day lacked, so I guess it could have been
> worse. (Branch And Link Register opcode indeed.)
>
>
> Frank Durda IV - only this address works:|"The Knights who say "LETNi"
> | demand... A SEGMENT REGISTER!!!"
> You must remove the "LOSE" to mail me. |"A what?"
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* Origin: you cannot sedate... all the things you hate (1:229/2)
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