pnr
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Posts posted by pnr
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The last of the stuff has been mailed out - minus a set of the Marinchip documentation. Anyone want that who is willing to add it to the archive?
What Marinchip documentation is that? Is it different from the MDEX documentation available at:
http://www.powertrancortex.com/documentation.html
??
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Actuallly from a technical perspective I found the Multiplan cartridge to be very interesting.
About 5 years ago I bought a bad-quality xerox copy of a document that detailed the C interpreter Microsoft used for implementing Multiplan on the TI-99/4A.
I have no clue where I put the document, from time to time I've been looking for it, but without any success so far.
To be more specific:
If my mind serves me well, there's some kind of "bytecode" interpreter in the multiplan cartridge (handling some Microsoft specific C dialect)
Presume that the multiplan source code itself was mostly the same for all different home computer platforms out there.
The only thing they needed to implement for each individual platform was the interpreter itself.
The document was supposed to get scanned and added to the development resources thread... Oh well, I guess one day I'll find it somewhere
I think the documents you refer to were posted in the yahoo group some 5 years ago:
https://groups.yahoo.com/neo/groups/ti99-4a/conversations/topics/72673
https://groups.yahoo.com/neo/groups/ti99-4a/conversations/topics/72672
The '673 document is the main specification, the '672 document is an addendum/errata to the former. It says that once upon a time Microsoft had a reference implementation in C for this spec, and also that the spec should be complete enough to write one from scratch. Has anyone ever attempted a disassembly & analysis of the Multiplan cartridge ROM?
This p-code looks quite well done, allowing substantial programs in little memory. It has a single 64K data space for global data and the stack, and an essentially unlimited segmented code space: the code is divided up into relocatable "segments" that are paged in and out as needed. Also, the p-code looks very tight, packing many C operations in a single byte.
If there is a reimplementation of this, and if someone has an old Microsoft C compiler (i.e. one of the DOS 16-bit compilers) that still supports generating this p-code, we would have another great tool for writing new software.
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I'll measure the tall pins tonight to see how tall they are. If you install a socket and use a tall-pins F18A, then it will probably give the needed height. Let me make sure though.
Perhaps this photo helps. This board has a socket (strip) fitted for the F18A. The CF Card breakout board comes about as high as a socketed DIL package.
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Actuallly from a technical perspective I found the Multiplan cartridge to be very interesting.
About 5 years ago I bought a bad-quality xerox copy of a document that detailed the C interpreter Microsoft used for implementing Multiplan on the TI-99/4A.
I have no clue where I put the document, from time to time I've been looking for it, but without any success so far.
To be more specific:
If my mind serves me well, there's some kind of "bytecode" interpreter in the multiplan cartridge (handling some Microsoft specific C dialect)
Presume that the multiplan source code itself was mostly the same for all different home computer platforms out there.
The only thing they needed to implement for each individual platform was the interpreter itself.
The document was supposed to get scanned and added to the development resources thread... Oh well, I guess one day I'll find it somewhere
If you do find it, I would be highly interested in a copy. It sounds like that document has documentation for the p-code part of Microsoft's "revenue bomb" C compiler (see here for some background). I think this p-code interpreter later evolved into the Visual Basic runtime, but that is speculative. Having a re-implementation of this bytecode interpreter, combined with old versions of Microsoft C that still included "cs" may lead to an interesting compiler option for the TI (it is said to create very tight binaries).
By the way, the fathers of this compiler, Charles Simonyi and Richard Brodie, are key figures in the microcomputer revolution of the 80's, driving the development of what eventually became Microsoft Office -- starting with defining the very concepts of it while at Xerox' PARC labs back in the 70's. Their wikipedia pages make interesting reading.
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And just out of curiosity, who of you uses the F18A with another computer than the TI-99/4A?
The MiniCortex I'm designing has an F18A. The MiniCortex is a eurocard sized SBC with a 9995 CPU and roughly modeled on the Powertran Cortex (schematics). It started out as an extended version of Stuart's breadboard design for the 9995.
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Thank you! This is an EXCELLENT explanation. I’m going to use some colors to clarify.
BLACK, my own comments / questions
RED, I don’t understand
GREEN, perfectly clear
BLUE, don’t agree
Although, I’m not sure what you could explain more or better about the subject.
How about a bit of history?
The TI990 was designed as a successor to the TI960 and TI980 computers. The TI960 was a process/production control computer, quite similar to what we would now call a PLC. Its purpose was to interface to all the sensors and actuators of an industrial plant, and that is where the bit addressability comes in handy. A brochure for the TI960 is here:
http://bitsavers.informatik.uni-stuttgart.de/pdf/ti/960/960Flyer.pdf
The CPU would interface to multiple cages with I/O cards through a simple 15 wire bus (12 address, cruin, cruout, cruclk).
The TI990 operated two busses that were physically separate, the CRU bus (to communicate with industrial I/O cards) and the TILINE bus (for memory, disk controllers, etc.). As mentioned in an earlier post, the TMS9900 multiplexes the two buses onto shared pins. Up to 7 I/O cages could be hooked up, with up to 24 cards in each cage. A card typically provided 32 I/O's. A description of how TI envisioned the TI990 series can be found here:
Section 2.1.10 has an extensive explanation of the above.
The TI960 heritage was also one of the considerations in choosing the workspace concept for registers, or so it seems.
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The Asgard Software Archive
in TI-99/4A Computers
Posted
Okay, colour me interested.
There are a few pieces of Marinchip M9900 documentation here:
http://quantums.info/cortex/MPE%20documentation/
(CPU board, RAM board, I/O board). Is it that?
If it is something other, I'm willing to do the scanning. However, I'm based in Europe.