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TI(ny)-99/4A Computer


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Personally I would dump TI Basic for the simple reason instead to increase the extra 16K GROM to be 24K of OS in GPL and 8K ROM.

i.e. GROM 0 (current OS), GROM 1 (currently TI BASIC), and GROM 2 (currently TI BASIC) also of course ROM 0 (Assembly OS)

 

RXB can run 99% of TI Basic programs especially if you put my REA TI Basic support routines there at that GROM space (4K used),

the computer does not know the difference between a CALL LINK called by TI Basic or XB, how they are handled in Assembly are the

same. And with 12K of added OS GROM a better memory manager could be created to take advantage of the SAMS memory. Not to

mention a F18 MK2 VDP memory manager also.

 

So your board would be able to be the most advanced TI on a single board.

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You mean that I should remove TI-Basic and replace it with RXB? It is a pretty good idea, I like RXB very much. Can you tell me the way to do?

 

That's done, I succeed to reintegrate the third expansion slot :)

No I said I have written Editor Assembly support that goes into where TI Basic Resides taking less than 4K space, and TI Basic currently takes 12K of the 16K space available.

 

This leaves 12K of open spaces when TI Basic is removed.

 

On a side note RXB can run 99% of TI Basic routines, and STANDARD XB CALL LINK will run those same LINKS but no TI Basic as XB does not support characters 144 to 159,

which RXB does.

 

Just socket TI Basic chips so can be replaced, in the future. (After RXB 2018 I am working on a upgrade to TI GPL OS)

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  • 5 weeks later...

I introduce you the microcomputer TIny-99 / 4A version 2.3
This project, following the TIny-99/4A v1 project, brings several modifications and improvements. Starting with a significant reduction in the size of the motherboard. It measures 25.1cm x 21.6 cm, a small size considering the number of embedded components.
The micro-computer, still architectured around the TMS-9900 now has more memory. In addition to the 32KB memory expansion it adds 1MB of SAMS RAM memory, which can be extended to 4MB. Other new features: the Real Time Clock and two additional expansion slots which now increase to 3 the number of cards that can be plugged to the motherboard. The very first TIny-99/4A initially used the VDP TMS-9929A, now it can also receive a TMS-9918A (NTSC version). Some other details will be presented soon.

Here is a picture of the first assembled motherboard of TIny-99/4A v2.3:
For information, the motherboard is on 4 layers and represents nearly 400 components for a total of 2284 pins.

Note: The small card (that only contains the 2 SAMS SRAM chips) that goes to the RAM expansion slot (near the 74LS612) not appears on the picture. I will take one soon)

tiny994av23-top-us.jpg

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  • 3 weeks later...
<snipped>

Back in the 70's TI made a device called the University Board. Basically a 9900, some ram, a small monitor in rom and a modified calculator. You would just key in assembly code on the calculator. Would you want to create Parsec? No, but it was pretty fun for learning assembly and testing yourself by writing small programs on paper and getting them to work. So, would I like to have a brand new University board, YEP!

 

<snipped>

 

Dan

 

Not meaning to derail this thread, but... Interesting that you mentioned "...Would you want to create Parsec?..." on a University Board. Funny thing is, that - indirectly - the University Board played a big role in creating Parsec.

 

During my first co-op/intern stint at TI Home Computer I borrowed a University Board and played with it (a lot!) after work. I cut my teeth on TMS9900 assembly language with the University Board, because at that time there was no 99/4A assembler package. Heck there wasn't even a 99/4A - only the 99/4. So the University Board was the only system I could take home and work on after a TI work day.

 

After my first co-op term TI let me take it back to college with me. The result of that was a University board project that interfaced a PAIA 3 octave keyboard with two TMS9919 sound generators. When I returned to TI for a second co-op term the 99/4A was about to be released. While the Mini Memory was being developed we wanted users to be able to experiment with assembly language programming without needing a PEB. I remembered how much I liked the University Board line-by-line assembler, so we located the source code for it in TI and I ported it to the Mini-Memory.

 

Shortly after we finished up with the Mini-Memory, TI management paired Jim Dramis and I together with the directive, "We want you to work together to make a space game". That was all of the direction we had. The experience gained, errors made, and hours spent, on the University board and LBL assembler were definitely a part - indirectly - of creating Parsec.

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  • 1 month later...

Thank you Urbite!

 

I received (and populated) the mini PCB for the SAMS memory expansion and the derivation of the cartridge connector (to fix on the case). So I can say that the electronic part of the computer is nearly completed, I am just waiting the keyboard PCB that I have realized and ordered.

The small PC case that I had in sight to adapt it to my TIny-99/4A v2 motherboard is out of stock, I have to wait for it to be available.
In the waiting I have made another case for the motherboard, a case which I planned to make later for a fully loaded setup, equipped with two 3.5" floppy drives and two SCSI hard drives. This Flex-ATX PC case is a little larger than the first one.
The case is based on the Corsair Carbide Air 240, healy modified: The metal plate that holds the motherboard has been lowered to permits the housing of TI cards (they are higher than PC cards), holes cut on the front panel for the floppy disk drives and the cartridge port, and for Turbo LED segments too. Creation of a metallic cage for disk drives and a dock for inserting cartridges. The rear side has been modified too, for accessing to the several connectors (vidéo, joystick, keyboard, ...). Note that it's just a proof of concept and not an official computer case. The motherbard will be available with a SAMS card, a cartridge extender connector, power cables and a keyboard but without a case.
Here is a picture:

tiny-994a-v2-desktop-2-small.jpg

 

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