After 41 years, my first assembly program on my first computer, the Tomy Tutor(oldvcr.blogspot.com)
oldvcr.blogspot.com
After 41 years, my first assembly program on my first computer, the Tomy Tutor
http://oldvcr.blogspot.com/2024/03/after-41-years-my-first-assembly.html
27 comments
The backstory of the Tomy Tutor is interesting. This seems like it was a tremendous longshot, financially. It’s hard to imagine how this would be greenlit in today’s age. There are so many weird architectures of the 1980s — I appreciate the quirkiness and diversity.
The home computer boom of the 70's and early 80's was the product of cheap microprocessors entering the market in the 1970's (chiefly the 6502 and Z80). In some cases it was scrappy startups (e.g. Apple) and in others it was an attempt to get in on the gold rush. There were no "standards" yet; IBM had yet to enter the fray, and when it finally did in 1981 it was still way too expensive for most of the home market, so wasn't really a factor for years.
So the way to think about this period is like the Internet boom of the late 90's or the AI gold rush of today. Things got greenlit because no one quite knew what would be successful (frankly, most companies/people struggled to find a use for the 8 bit machines besides gaming, which is a hard sell to a lot of parents). The quirkiness of the architectures is a direct result of the industry being the Wild West. You wouldn't see it today because the industry has been established.
So the way to think about this period is like the Internet boom of the late 90's or the AI gold rush of today. Things got greenlit because no one quite knew what would be successful (frankly, most companies/people struggled to find a use for the 8 bit machines besides gaming, which is a hard sell to a lot of parents). The quirkiness of the architectures is a direct result of the industry being the Wild West. You wouldn't see it today because the industry has been established.
Not sure it was hard sell. The computers were expensive but people knew they are the future. Parents who could afford it would buy it for the kids just to have access to the computers without knowing what good they are for.
Maybe if they were rich, but computers were bordering on new-car expensive in the 80s, and were indeed a hard sell for most working-class American families. Even something as basic as a Commodore 64 could cost you a few hundred dollars, and that was before the accessories got involved in it -- some of which you needed if you wanted to save programs or run commercial software. Some parents could be swayed by the computer's educational value in teaching things like math, reading, grammar, and geography, hence the glut of edutainment titles available for the early 8-bit machines. But even in the affluent town where I grew up, very few of us kids actually had computers.
The real winners of the home-computer revolution were the ones who knew how to cut costs effectively, companies like Commodore and Sinclair, in order to grow the market -- and the market only really grew once component prices started falling once the 80s were underway.
My family was... a little different. My father, a mechanical engineer, actually had a use for computers in the home: when the force and mechanical advantage calculations on your novel engine design became too complex for programmable calculators, a more powerful desktop computer was just the tool needed. He got me a VIC-20, and later a TI-99/4A, so I would keep my grubby mitts off his expensive Tandy business machine.
The real winners of the home-computer revolution were the ones who knew how to cut costs effectively, companies like Commodore and Sinclair, in order to grow the market -- and the market only really grew once component prices started falling once the 80s were underway.
My family was... a little different. My father, a mechanical engineer, actually had a use for computers in the home: when the force and mechanical advantage calculations on your novel engine design became too complex for programmable calculators, a more powerful desktop computer was just the tool needed. He got me a VIC-20, and later a TI-99/4A, so I would keep my grubby mitts off his expensive Tandy business machine.
A shame those TMS99xx were limited so severely by design of the systems they were in. Seems like a decent CPU family, and with proper 16-bit bus + enough RAM could have made for nice contenders in the home computer market.
But 256 byte scratchpad RAM, 16K accessible only through the videochip (and not from BASIC!?!), in 1983? Too little too late, regardless of price. C64's, ZX Spectrums etc were everywhere by then. Much more capable and not that expensive.
But 256 byte scratchpad RAM, 16K accessible only through the videochip (and not from BASIC!?!), in 1983? Too little too late, regardless of price. C64's, ZX Spectrums etc were everywhere by then. Much more capable and not that expensive.
Interesting how the connotations of parent guidance have changed over the years. It’s pretty rare these days to see “no parental guidance necessary.”
I believe my first "computer" could have been the toy version of the Tomy Tutor:
https://www.nostalgianerd.com/tomy-tutor/
https://www.nostalgianerd.com/tomy-tutor/
Bless this guy's parents.
Me a couple of days ago:
https://twitter.com/thibaut_barrere/status/17711464663602670...
I am really grateful!
https://twitter.com/thibaut_barrere/status/17711464663602670...
I am really grateful!
Cool! I just wrote my first assembly program for the TI-99/4A, and am working on a TMS9900 assembler.
(author) I thought AS worked pretty well. The syntax is a little idiosyncratic but it "just worked" once I learned its pet peeves, and it seems to have specific support for the added 9995 instructions.
Have you found your way to Stuart Conner's page? http://www.stuartconner.me.uk/
Lots of resources on the original TI dev boards and tools for TMS99Xx.
Lots of resources on the original TI dev boards and tools for TMS99Xx.
Thank you, that’s a great site. There goes my Sunday morning!
I used AS to write the program, and it is my "reference assembler" for the one I am writing. I just wanted to see if I could write a working retro assembler.
I just realized I have a 9995-based Tomy Tutor in my closet. Now that I know about this project, I'll have to dig it out. FWIW, for the two years I lived in Richardson, TX, I drove by TI mainside every day to get to work. I eventually remembered how much fun 9900 assembly was and got the vanity plate BLWP [Branch and Load Workspace Pointer], one of the most unique 9900 instructions.
The title alone speaks to me.
Thank you for the article.
Very interesting article, but the architecture seems quite odd. And the journey to cut to japan and back not helping. Still like second extinction, it showed the variety when you think odd. It also asked my earlier question about zero page architecture… lately the idea of having large cache under amd might be another evolutionary path btw.
60 years ago, I never got to debug my first assembly program, which had 1 syntax error and an unknown number of bugs, because NASA launched a weather satellite, data from which monopolized the 7090 which the high school enrichmment program was having programs run on. Still rankles a bit.
I’ve recently been disillusioned in my admiration for NASA.
How NASA used a child math prodigy back in the 1970s: “ At that time, I led my life like a machine – I woke up, solved the daily assigned equation, ate, slept, and so forth. I really didn’t know what I was doing, and I was lonely and had no friends.”
Career scientists and engineers using a kid like this? Pretty scummy in my book.
Compare that to how Srinivasa Ramanujan was treated nearly a century earlier by the British.
Sadly, your schools’s computer time wouldnt have made anyone blink.
How NASA used a child math prodigy back in the 1970s: “ At that time, I led my life like a machine – I woke up, solved the daily assigned equation, ate, slept, and so forth. I really didn’t know what I was doing, and I was lonely and had no friends.”
Career scientists and engineers using a kid like this? Pretty scummy in my book.
Compare that to how Srinivasa Ramanujan was treated nearly a century earlier by the British.
Sadly, your schools’s computer time wouldnt have made anyone blink.
If it's the British and the treatment of the brilliant people, the story that comes to mind is of Alan Turing.
https://en.wikipedia.org/wiki/Alan_Turing#Homosexuality_and_...
https://en.wikipedia.org/wiki/Alan_Turing#Homosexuality_and_...
Very poor example.
Technical brilliance didn't protect Alan Turing from a badly-written sex law pushed out in 1885, but technical brilliance wasn't the cause of his mistreatment.
Whereas it was technical brilliance that made a young, 8-year-old 210 iq child the target of exploitation by NASA in an era where child-exploitation was already frowned upon for decades.
And of course, in the height of irony one of the aims of https://en.wikipedia.org/wiki/Criminal_Law_Amendment_Act_188... was to protect the very young; so a very poor example indeed.
Technical brilliance didn't protect Alan Turing from a badly-written sex law pushed out in 1885, but technical brilliance wasn't the cause of his mistreatment.
Whereas it was technical brilliance that made a young, 8-year-old 210 iq child the target of exploitation by NASA in an era where child-exploitation was already frowned upon for decades.
And of course, in the height of irony one of the aims of https://en.wikipedia.org/wiki/Criminal_Law_Amendment_Act_188... was to protect the very young; so a very poor example indeed.
[deleted]
Oh wow, I remember these, barely. I never used one though.
The TMS9900 was made in I²L bipolar technology, not MOS. Texas Instruments also had a 4 wide bitslice using the same fabrication process.
You must confuse TMS9900 with other TI integrated circuits, perhaps those used for TMS990.
TMS9900, which was 16-bit CPU in a big 64-pin package (like that used later by Motorola MC68000) was certainly made in an NMOS technology.
See e.g. Wikipedia:
https://en.wikipedia.org/wiki/TMS9900
There is no doubt about this because TMS9900 required -5 V (for substrate bias), +5 V and +12 V (for enhancement MOS load transistors), like all early NMOS ICs, e.g. Intel 8080. No bipolar technology would have needed such power supplies.
The later TMS9995 was also made in an NMOS technology, but in a more modern variant with depletion transistor loads, which required only a single +5 V power supply, like Zilog Z80 and other more recent NMOS CPUs.
TMS9900, which was 16-bit CPU in a big 64-pin package (like that used later by Motorola MC68000) was certainly made in an NMOS technology.
See e.g. Wikipedia:
https://en.wikipedia.org/wiki/TMS9900
There is no doubt about this because TMS9900 required -5 V (for substrate bias), +5 V and +12 V (for enhancement MOS load transistors), like all early NMOS ICs, e.g. Intel 8080. No bipolar technology would have needed such power supplies.
The later TMS9995 was also made in an NMOS technology, but in a more modern variant with depletion transistor loads, which required only a single +5 V power supply, like Zilog Z80 and other more recent NMOS CPUs.
You are correct as is the other reply to my post. The chip in chapter 3 of the 1977 "The Bipolar Microcomputer Components Data Book" from Texas Instruments is the SBP9900 processor, not the TMS9900. I had never noticed this detail before and always had used this book as my reference for the 9900.
SBP9900 is the I²L version, found atleast in older M1 Abrams:
https://www.eevblog.com/forum/projects/reverse-engineering-a...
https://www.eevblog.com/forum/projects/reverse-engineering-a...