So, for whatever reason, you are reading my fantasies about an alternate world where computer and information technology took a significantly different turn in the early 1980s. Maybe you started with the different Mac OS-9 that could have been. Maybe you have read the beginning of the 33209 technology timeline or the beginning of my story about the the alternate world of the 33209.
At this point, the timeline has gone well beyond what I have published of the 33209 story, but I'm going to keep plotting it out in advance because I've hit a writer's block on my stories. I'm not sure the timeline here will match the story as it plays out, though.(You're not sure you're interested? How odd. ;-)
* Summer 1981:
In late June, Several engineering and CS students from University of Texas's main campus in Austin come to visit, ask to join the group for the rest of summer, and are accepted in. Some of the UT Austin group are undergraduate, some are doing graduate work.
Microware formally begins a top-secret project to re-write OS-9/6809 to use a split stack and merge in other features and concepts from Susumu. TSC begins publicly announced re-writes of both Flex and Uniflex, merging features from Susumu into their systems. Both Microware and TSC begin developing versions of their OSses for the 68000, as well, Microware secretly and TSC publicly.
IBM and Apple collaborate with the Microware and TSC OS projects, Apple
openly about the non-top-secret projects, IBM on the quiet. Various students from the group are invited to Clive and Chapel Hill for short internships, as well.
Bill Mensch and others from Western Design Center request to be permitted to come observe the research group's work, and, after a short discussion among students and sponsors, are allowed to visit.
By the end of June, the students working with TI's new version of the 9900 have gotten their prototypes running most of Susumu, better than the ports to the other processors except for the 6809, 68000 and 682801.
More games, and more complex games are evidence of the functionality of the language and the system, and, with other applications that the students develop and share, help motivate the students to add support for modularization and versioning (tracking and control) to the language.
Versioning drives the development of archiving tools, and those who hadn't yet built fast tape hardware for their systems do so, for the mass storage necessary for backup and archiving. Even at a mere 4 kilobaud with one bit per baud, one channel of one side of a forty-five minute cassette yields the storage capacity of several of the floppy diskettes of the time. (Cassettes longer than twenty-three minutes per side tend to stretch more quickly, so the students generally tend not to use 90-minute or two-hour cassettes, except for permanent one-time backups.)
Several of the students develop control hardware for their cassette recorders or cassette tape decks, to allow various levels of computer control.
Apple releases its first models of the Apple IX line running OS-9 on the 6809 in early July, using the 6847 for console video output and the 6845 for optional workstation video output. The BIOS ROM is essentially Susumu.
Also in early July, more magazine articles appear, including rushed articles discussing early versions of Split P and the common code base. Outside the group, Split P generates particular interest at Bell Labs and the parent telephone companies.
And also in early July, Motorola offers the group samples of the upgraded 6809s and 6845s, along with integrated support chips for the upgraded 6845, and most of the group who are not out for the summer volunteer to experiment with the parts in various configurations, including using 6845s with non-Motorola CPUs.
Within a few days, students have Micro Chroma style computers with the upgraded 6809 running Susumu, using the 68471 for video output. Computers employing the upgraded 6845 take a bit more time to get up and running, but several are running within a week and work begins on improving the code generation for the processor's new features.
The UT Austin students arrange to move their coursework to the local branch of UT for fall semester so they can continue to engage with the group.
Bill Mensch arranges with a couple of the UT Austin students to help him design an upgrade to the 6502 that will be optimized for Susumu and Split P, and returns to Mesa.
And also early in July, a couple of students get interested in text
windows on the Univac terminals and starts trying to implement them in
their own computers. One of the teachers mentions the Xerox Parc project
and graphical user interfaces, and several students begin back-burner
on-again, off-again projects trying to figure out how to make such a
thing work. Various experiments in pointer devices are attempted. Joysticks are quickly produced, and functional light pens have been produced for the 6845-based displays by mid-July. Various attempts at tracking a pencil writing or sketching on a page are attempted, without much success.
And again, also starting early in July, inspired in part by the dc/bc basic calculator the students have discovered in Unix and in part by Tiny BASIC, a group of students work to re-implement dc on top of the Forth grammar of Split P, and then re-implement bc on top of the C grammar. They then extend both with formatted output and other functions usually found in BASIC. At IBM's request, they add graphics and sound functions, and certain functions useful in a business environment.
Overall, July sees more general steady progress, with Susumu becoming stable on the upgraded version of the 9900, and, towards the end of July, on the other non-Motorola CPUs.
Discussion of a license for Susumu and the hardware the students are developing reaches a head, and a software license similar to the licenses Berkeley and MIT would later in our reality use for open source software is produced by the students and approved by the college, with help from the sponsoring companies.Several hardware design licenses are produced and approved by the college, and the college and the sponsoring companies help arrange for patent research and applications.
More stringent sharing agreements are established for participating in and getting support from the research group, similar to the openBSD project source code requirements and the software freedom terms of the GNU Public License that would develop later in our reality.
Unix on the 6801 remains a bit slow but usable. It is a bit snappier on the 682801, more so on the 6809, even more so on the new version of the 6809.
Unix is even more usable on the 68000, even though virtual memory management functions on the 68000 can't be handled well without a full memory management unit. Simple bank switching in an address space as large as the 68000's is, of course, not very workable for hardware memory management. And, of course, the students haven't quite figured out virtual memory yet, anyway, even
with the help of the UT students and some industry engineers. The complexities of virtual memory were not generally well understood at the time.
Experiments begin with using four of the 68000's address registers as explicit run-time segment registers for Unix, mirroring their use in Susumu, to help work around lack of memory management.
Similar experiments in segmentation on the 8086 do not fare as well, because of the design of the 8086's segmentation, but still proceed.
In very early August, Motorola publicly announces sampling of an upgrade to the 6809:-
Instruction timings for the 681809 are brought up to par with the 6801 and
682801, and the 681809 is announced as an SOC core with most of the I/O library for the 682801 available, including on-board DMA
and bank switching.
-
The 6809 already has direct page mode op-codes for the unary instructions,
so that doesn't change. However, the direct page mode has been added to the
index post-byte, allowing memory indirection on direct page variables and
use of the load effective address (LEA) instruction to calculate the address
of direct page variables.
-
A new I/O page register similar to the direct page register is added. Unlike the original DP register, there are no op-codes allocated for I/O page access. Addressing via the IOP register is implemented entirely as a new mode in the index mode post-byte, and access is entirely via arguments to the TFR and EXG instructions.
Since no codes for the IOP are available to the PSH and PUL arguments, pushing and popping IOP require transfer through another register. Since the IO page is considered more of a hardware design constant, this is considered to probably not be a great bottleneck in the use of the IO page.
-
64 byte spill-fill stack caches are implemented for the S and U stacks,
similar to those in the 682801, but with a shorter spill point for S, to cover the
larger register set -- 22:34:8.
- In addition to the stack caches, the initial SOC versions of the 681809 has a half-kilobyte of internal RAM for use as fast direct-page RAM.
-
User and system modes are also implemented similarly to the 682801's. Access to the I/O page register can be prohibited in user mode, generating a new memory access violation interrupt.
-
Likewise, address mode function code outputs are provided, indicating addresses relative to
the PC, to the S stack, to the U stack, to the direct page, to the I/O page, to
extended (absolute) addresses. Two codes of eight are reserved.
Because the index post-byte provides the ability to specify each of the separations, address space use for the 68109 is much more flexible than for the 682801 when the address space can be determined at compile time.
As with the 682801, utilization of the extra address space is expected to require caution. However, since the index post-byte can specify the mode and therefore the space being used, the 681809 should be able to use the extra space more effectively, as long as the space is known at compile time. Better gains in address space are expected:- code <= 64K
- general data <= 64K
- direct page <= 256 of 64K (because of the direct page register)
- I/O page <= 256 of 64K (because of the I/O page register)
- parameter stack <= 64K
- return stack <= 64K
With the 681809, the actual aggregate active memory space per process is expected to be able to often exceed 128K, but not typically exceed 192K. Again, work with Susumu and Unix bears these expectations out.
- The initial SOCs provide bank switching somewhat similar to the 682801's. But the mapping registers have four more bits than those on the 682801, allowing maximum physical addresses of 16M. With the larger maximum address space, bank switching is simplified for the two stack spaces and the direct and IO pages.
- Small integer hardware division per the 682801 is also provided.
Motorola also announces the Micro Chroma 681809 as a prototyping kit for the new processor and the 68471, again with Susumu in ROM.
Improvements in the 68455 over the 6845 are not as easy to quantify, being mostly a redesign to better fit a video cache used for either text or graphics, along with improved support for hardware scrolling and generally improved graphics support. Modes which switch between direct pixel output and character ROM mapped output simplify the support circuitry for designs that include being able to switch between graphics mode and text mode screens.
New support circuits for the 68455, to simplify the digital-to-analog output conversion for color and gray-scale are announced, along with a companion DRAM refresh/bus arbitration part, the 68831 68835, capable of directly supporting up to 512 kilobytes of video RAM, and a nearly identical 68832 68837 that includes bank switching for the the CPU side, for processors that can't address large address spaces on their own.
TI announces the 99S200, a version of the 9900 with the local stack frame implemented as entries in a spill-fill cache instead of in general memory. In addition, the 99S200 adds a separate return address stack with spill-fill caching and improved call overhead, and removes the PC entry in the local stack frame. The 99S200 does retain a 512-byte internal bank of fast RAM. SOC parts and libraries are also announced, initial SOCs including both bank switching and DMA.
TI also announces the 99V180 video display, compatible with the 9918A, but supporting up to double the 9918A's horizontal and vertical resolution, if the external digital-to-analog circuitry and display device are fast enough.
And TI announces the TI-99/16 home computer, utilizing the new processor and video generator in a memory configuration less constricted than the 99/4, with both Susumu and an improved 99/4 BASIC compatible BASIC in ROM. A simplified version of the main circuit board for the new home computer is also made available as a prototyping kit, with only Susumu in the ROM.
Shipments of the 99/16 are expected to begin in plenty of time for Christmas.
A few days later, Motorola pre-announces the 68010 about a half a year ahead of
the announcement in our reality, with the improvements seen in our reality:
- The Popek and Goldberg virtualization features,
- Exception stack frames corrected to allow recovery from bus faults,
- Three instruction loop mode,
- Vector base register,
-
And improved instruction cycle counts for certain instructions.
-- and a little bit more:
- New addressing modes -- 32-bit constant offsets for indexed modes and branches.
- New 32-bit integer multiplies, with 32-bit and 64-bit results, and new 32-bit by 32-bit divide and 64-bit by 32-bit divide instructions.
- A new system-mode A6 is provided in addition to the system-mode A7, to better support split-stack run-times.
- Four spill-fill stack caches are provided, one each for system and user mode A7, and one each for system and user mode A6 as a parameter stack.
At the same time as the pre-announcement, samples are made available to the research group, and students dig into it, helping Motorola debug the design in much the way the students helped debug the 99S200.
A few days later, moving plans up under pressure because of TI's announcement of the 99/16, IBM announces the IBM PC in two models, the Business PC/09 based on the 681809 with bank switching, and the Family PC/88 based on the 8088, both with video based on the original 6845. Both models start at 16K of RAM expandable on the mainboard to 64K. The 640K address space limit we are familiar with is present on both the PC/88 and the PC/09, but the PC/09 adds a second connector for each card slot, similar to the AT bus that would later be used in our world, that allows full 16M addressing, making the boundary mostly irrelevant. Pricing for the both models is comparable, $1500 for the PC/88l, 1525 for the PC/09 model.
Neither comes with disk drives, but disk drives are an option. Both have built-in cassette I/O interface and simple sound generating devices.
Both models offer integration with existing third party OS products -- CP/M or MP/M for the 8088 and Uniflex-S/6809 or OS-9S/6809 for the 681809, and both already have software and hardware products that allow integrating these PCs as workstations into IBM's mainframe and mid-range systems.
OS-9S is a split-stack version of OS-9 based on OS-9 level 2 and Susumu, now no longer top-secret. Uniflex-S is based on Uniflex and Susumu.
Both have Susumu as their BIOS in ROM, and both include (as something of a last minute addition) the students' extended dc/bc languages in the ROMs.
A third model is also announced, based on the (alternate world) 68010 which Motorola has just announced. It starts at 32K RAM installed on the mainboard, but otherwise has a similar design to the 6809 version, including the expanded bus connector, but with a full 16-bit data bus. Uniflex-S/68000 and OS-9S/68000 are available OSses. Pricing starts a little higher, at $1750.
Neither Microsoft BASIC nor PC-DOS are mentioned.
In answer to questions about models based on other processors, IBM specifies a product concept that focuses on the software rather than the hardware. They do not commit to using other CPUs, but they do mention development research on the 99S200 and the newly announced Z8001S. They do not mention their own ROMP.
A week after IBM's announcement, Radio Shack rushes to announce their own OS-9/6809 compatible model, the TRS-09 Color Business Computer based on, and compatible with, their original Color Computer. It includes a built-in DMA controller, with the Color Computer's Multi-Pak interface, a floppy disk controller, and two hardware serial ports in addition to the single CPU-intensive bit-banging port of the Color Computer also built-in. It boots to Microsoft Disk Color BASIC, but the DOS command can load an operating system from a floppy disk or ROM pack. Two cartridge slots for ROM packs are brought out to the side, the other two slot circuits being used internally for the built-in I/O. It comes with 16K of RAM, upgradable to 64K. Price and branding adjustments are also announced, with sales personnel pointing out that the entry level price is only half the price of an IBM PC/09.
The limit to RAM expansion is swept under the rug, but the magazines dedicated to Radio Shack's computers all point it out.
The two students who are under NDAs with IBM Instruments go to
Danbury again for short internship sessions, and return before school starts.
Efforts to find a source for CRTs are still not very fruitful, but the students have developed some approaches that allow a couple of them to write magazine articles describing circuits using the 68471 for TVs and steps to tune the output to individual TV models, to get legible text at 64 columns, or even 85 columns using 512 pixel wide lines and 6 pixel-wide characters.
Parents of several of the students meet with the colleges and the other companies that have been supporting the research group, and set up a company to handle commercializing their work. Arguments arise, but a small core group of seven of the students (who have just returned from a little vacation to Japan) work hard to bring everyone to agreement.
A non-profit research group is set up, and the students take membership in it.
Additionally, a for-profit development company is set up which can act as agent for the students in accepting contract work.
Microsoft attempts to sue IBM for getting shut out of the PC product, but IBM legal has their response already prepared. A legal skirmish commences, with public news coverage generally portraying Bill Gates as a modern David against IBM's Goliath.
Tandy/Radio Shack wakes up and sends lawyers, and then wakes up again and sends engineers, too. After some discussion and belated agreement to follow the licenses and consortium rules, they are allowed to join the sponsors' consortium.
Western Electric also approaches the group, but do not seek membership in the consortium because of their monopoly status in the communication industry. Top-level negotiations on the licensing of Unix ensue between the Susumu Sponsors Consortium and Western Electric and several other communications industry companies and educational institutions. The core student group participates, along with counselors and legal help from the college and university, representing the students' interests.
IBM Instruments again sends engineers to observe the students' work, and spend considerable time discussing both Susumu and Microware's OS-9 with the two NDA students and members of the core student group.
The core student group members all complain quietly about having to take time away from their own projects to deal with all the side issues.
As summer break ends, a group of foreign exchange students arrive from Japan, mostly on education/research leave from Japanese companies. This creates a bit of confusion and friction, but the core group members manage to iron things out and they join the research group.
~~~~~
