Computing History: Exploring The TI-99/4A
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Date: 2025-12-23
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Comments and reviews: 12
garymartin9777
These guys didn't mention the heart of the system -- the TMS-9900 -- thus the 99 namesake. This was the first 16-bit microprocessor, released in 1976. It had a true 16-bit ALU and 16-bit memory interface. In order to save transistors, hence die area, making it manufacturable at that time, the 16 ,16-bit registers were actually memory locations referenced relative to a register pointer. This provided for fast context switches (later also found on Sun's SPARC processor) but compared to on-board registers was slow for register operations. The 99-4A video chip used a ram that could only be loaded by the processor, not by the usual Direct Memory Access. This also degraded speed. The TMS 9900 ran at 3 MHz, which for 1976 wasn't shabby. In 1978 I purchased a single card kit based on the 9900. This was unassembled so I got the PCB and a bag of chips which I had to solder on myself. It did have a serial port and as I recall a ROM with a debug tool so I was able prove it working. Unfortunately there was no software available for it at that time which is one reason the TMS 9900 didn't catch on.
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These guys didn't mention the heart of the system -- the TMS-9900 -- thus the 99 namesake. This was the first 16-bit microprocessor, released in 1976. It had a true 16-bit ALU and 16-bit memory interface. In order to save transistors, hence die area, making it manufacturable at that time, the 16 ,16-bit registers were actually memory locations referenced relative to a register pointer. This provided for fast context switches (later also found on Sun's SPARC processor) but compared to on-board registers was slow for register operations. The 99-4A video chip used a ram that could only be loaded by the processor, not by the usual Direct Memory Access. This also degraded speed. The TMS 9900 ran at 3 MHz, which for 1976 wasn't shabby. In 1978 I purchased a single card kit based on the 9900. This was unassembled so I got the PCB and a bag of chips which I had to solder on myself. It did have a serial port and as I recall a ROM with a debug tool so I was able prove it working. Unfortunately there was no software available for it at that time which is one reason the TMS 9900 didn't catch on.
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NickolasGaspar8bit
which was the first multimedia home computer which:
-Earned an EMMY Award as the first computer based teleprompter
-The first unmodified home computer ever used inside an coin op cabinet in order to make a specific game available to the arcades.
-The only home computer that is capable of reproducing full screen 256 color video files with pcm sound through a player.
-the fist system with a gfx co processor and a USB-like port.
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which was the first multimedia home computer which:
-Earned an EMMY Award as the first computer based teleprompter
-The first unmodified home computer ever used inside an coin op cabinet in order to make a specific game available to the arcades.
-The only home computer that is capable of reproducing full screen 256 color video files with pcm sound through a player.
-the fist system with a gfx co processor and a USB-like port.
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pcworld
The TI engineers didn't expect children to have the patience to switch off the computer when swapping cartridges, so they added a switch that will reset the machine when inserting or removing a cartridge. You can just yank one out and shove another one in with the computer still on and it will work. And they keyboard is indeed mechanical even though it is far from the best. The original joysticks are simply horrible, however.
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The TI engineers didn't expect children to have the patience to switch off the computer when swapping cartridges, so they added a switch that will reset the machine when inserting or removing a cartridge. You can just yank one out and shove another one in with the computer still on and it will work. And they keyboard is indeed mechanical even though it is far from the best. The original joysticks are simply horrible, however.
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TogonzoMedia
This was my 1st computer. I was 10 years old and my parents bought it for for Xmas in 1984 for like $50 and it came with TI Invaders. I programmed every single BASIC program in the book ... and Mr. Bo Jangles was a monumental waste of 4 hours on a Saturday. We also got an Atari 2600 that same Xmas - it was awesome.
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This was my 1st computer. I was 10 years old and my parents bought it for for Xmas in 1984 for like $50 and it came with TI Invaders. I programmed every single BASIC program in the book ... and Mr. Bo Jangles was a monumental waste of 4 hours on a Saturday. We also got an Atari 2600 that same Xmas - it was awesome.
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georgeh6856
The class clown in my junior high class had a TI-99/4A. He had the speech synthesizer option. One time, he called me on the phone and typed the words he wanted to say into the TI so its speech synthesizer would tell them to me over the phone. I had absolutely no idea what it was saying.
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The class clown in my junior high class had a TI-99/4A. He had the speech synthesizer option. One time, he called me on the phone and typed the words he wanted to say into the TI so its speech synthesizer would tell them to me over the phone. I had absolutely no idea what it was saying.
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jcugnoni
Ha.. brings me great memories of this kind of weird machine. I started my computer experience on one that my uncle gave me. It made me discover so much and learn to program, and operating the cassette was so weird but demystified the concept of data storage at the same time.
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Ha.. brings me great memories of this kind of weird machine. I started my computer experience on one that my uncle gave me. It made me discover so much and learn to program, and operating the cassette was so weird but demystified the concept of data storage at the same time.
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cacheman
From what I understand, the CPU is capable, but some unfortunate architecture design decisions (e.g most of the memory not being accessable directly by the CPU) resulted in a computer that feels very slow.
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From what I understand, the CPU is capable, but some unfortunate architecture design decisions (e.g most of the memory not being accessable directly by the CPU) resulted in a computer that feels very slow.
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AlexLC_07
In the 80s I used a professional version for 9900 application development. It included a plug-in replacement for the chip to allow In Circuit Emulation to debug programs. Memories .....
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In the 80s I used a professional version for 9900 application development. It included a plug-in replacement for the chip to allow In Circuit Emulation to debug programs. Memories .....
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zivzulander
Immediately watching the video on seeing the thumbnail partly because the keyboard caught my eye. So many vintage caps look so nice. Interesting history, too!
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Immediately watching the video on seeing the thumbnail partly because the keyboard caught my eye. So many vintage caps look so nice. Interesting history, too!
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AlexEvans1
Perhaps the first 16-bit personal computer or the first 16-bit microcomputer, but the PDP-11 was introduced in 1970 and there are probably others from earlier.
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Perhaps the first 16-bit personal computer or the first 16-bit microcomputer, but the PDP-11 was introduced in 1970 and there are probably others from earlier.
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asicdathens
I bought this in 1981 with lunch money, and whatever I was given. The model sold in Europe was plastic without the fancy metal overmolds
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I bought this in 1981 with lunch money, and whatever I was given. The model sold in Europe was plastic without the fancy metal overmolds
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thenoblerot
My first computer! It was so goofy! :) The built-in TI BASIC was terrible - the Extended BASIC command module was a must-have
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My first computer! It was so goofy! :) The built-in TI BASIC was terrible - the Extended BASIC command module was a must-have
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