It was called the Geneve 9640 from Myarc:
https://dressupgeekout.com/geneve/
http://www.mainbyte.com/ti99/geneve/geneve.html
Wikipedia has a decent article:
https://en.wikipedia.org/wiki/Geneve_9640
12 MHz un-crippled 16-bit CPU, 80 column text, 256 colour graphics, up to 2 MB of RAM.
That would be much more promising for a Unix-like OS!
They are extremely rare these days, but a cheapo emulation would be great fun -- it's able to run most software for the 99/4A.
Both are available in MESS.
"Would have been", surely? It never existed, did it? The Geneve shipped.
MESS is one thing. I am interested in something the size of a RasPi I can connect to a screen.
Think of something like this:
I owned a 99/8 (without Pascal GROMs), so for me it was definitely real! Extended BASIC II was onboard, and showed this:
> SIZE 62235 BYTES FREE
The manuals and most schematics are long known and archived at ftp.whtech.com. I have/had paper copies of many of them. Sadly, TI never archived any Home Computer work from Lubbock, TX. Those employees had been laid off or transferred just as TI got interested in preserving archives (starting in 1983. Described in Ed Millis book: TI, the Transistor and Me.
The TI Records are at DeGolyer Library, SMU but contain very few Home Computer folders. Conspicuously missing are the papers of CB Wilson, which turned up at an estate sale and were fortunately scanned.
Wilson's office in Dallas seems to have contributed a few things to the archives. That is typical: mostly executives and Fellows were canvassed for documents. Ed Millis revived obsolete floppy formats for the cause in 1983!
You might also try running Classic 99 under WINE. That works on my x86 MacBook. Classic99 has the legal license to ship with ROMs. (Well PC99 as well but it's hard to get.)
I'm not sure if JS99er runs standalone --that's a very good emulation in the browser, which you can load up anytime.
There is very little documentation with this device but fortunately several YouTubers have made long videos showing every detail of the replacement. Enjoy!
The TI-99/4A was the first computer I owned as a teenager. I had used TRS-80s and Apple ][ at school. I eventually bought the expansion box and a couple of accessory cards (floppy disk drive, memory and RS232). It all went in the e-waste dumpster about 20 years ago during a move.
My sister and I used to co-type programs from "Compute!". The times were so much simpler then..
Replaced it with a C128-D. Didn’t get my first intel until I bought a 386 after graduating high school. Good times.
Anyone up for a rousing game of Pole Position?
All due to TI’s desire to use the same chip standards across all their machines big and small, IIRC.
The 6502 is not very different with a very small number of registers and Zero Page being used for most of what a modern machine would use registers for. For example (unlike the Z80) there is no register-to-register add or subtract or compare -- you can only add/sub/cmp/and/or/xor a memory location to the accumulator. Also, pointers can only be done using a pair of adjacent Zero Page locations.
As long as you were using data in those in-RAM registers the TI-99/4 was around four times faster than a 1 MHz 6502 for 16 bit arithmetic -- and with a single 2-byte instruction doing what needed 7 instructions and 13 bytes of code on 6502 -- and it was also twice as fast on 8 bit arithmetic.
It was just the cheap-ass main memory (and I/O) implementation that crippled it.
It's arguably the only 8-bit computer which has a really different architecture from the others. You could otherwise imagine pulling the SID chip off a C-64 and putting it on a TRS-80 Color Computer etc.
Sharing the main RAM with video was a weak point in computers of that time period because the video system stole many of the memory access cycles. Some recent retrocomputers that revisit that period like
https://www.c64-wiki.com/wiki/Commander_X16
have a full-size memory bank and a video RAM memory bank which is accessed through a port which can be pretty efficient because you can auto-incremement the address register and just write 1 byte to the port to write 1 byte to video RAM and repeat.
UNIX99 uses an after market card with 1Mbyte of RAM on an 8bit external buss used for peripherals. This card replaces the old 32K RAM card made by TI in the 1980s.
The lack of dedicated registers meant a lot of memory access, which slowed things down considerably. This is probably why it never gained the same traction as the 6502-based systems like the Apple II or Atari.
I'm curious to see how this UNIX-like OS addresses those limitations. It's a pretty neat accomplishment if it can provide a usable environment on that hardware.
It gets worse because the TI99 only has 256 bytes of RAM directly addressable on its 16-bit bus. All the other memory in the system is video RAM and is accessed 8 bits at a time through the video display processor. Oh, and you can only do this when the VDP is not accessing the memory. This is incredibly slow and severely hobbles the potential performance of the CPU.
Supposedly what happened is that the system was originally designed to have either an 8-bit CPU, or a 16-bit CPU with an 8-bit bus (cf. 8086/8088) like TI's own TMS9985, but at some point it was decided that they should instead cram their full 16-bit TMS9900 minicomputer CPU (!) into the thing. This decision basically tanked the whole architecture.
It was too late/too expensive to redesign the 8-bit support chips to 16-bit counterparts so they had to make some really out there decisions like "talk to the graphics chip and give it an address to read/write every time you want to use memory" and "software is written not in machine code, but in GPL (Graphic Programming Language), which is then interpreted by the CPU and turned into actual TMS9900 machine code"
Software on ROM cartridge for the system is stored in GPL and is fetched from ROM by the CPU (but wait! The ROMs are not in memory space like they would be on a sane computer; they are SERIAL ROMs read 16 bits at a time with memory mapped I/O) and interpreted to machine code. This is slow. When you write your own software in BASIC, however, this gets worse: now you're writing BASIC, which is being interpreted and turned into GPL, stored in video RAM, and then fetched back from video RAM and turned into machine code by the CPU. THIS IS EVEN SLOWER.
Needless to say, the BASIC on the TI99 is dramatically slower than the already slow implementations on other contemporary micros.
It DOES have a full 16-bit CPU which is theoretically much more powerful than a 6502 or Z80 but this wild-ass implementation of... well, everything, makes the system probably the least capable machine of the era.
Context switching and message passing (synchronous anyway) are the same thing when you consider how rendezvous works.
BLWP instructions seem like this was “meant to be”.
That is old-school cool.
It's extremely slow, which isn't surprising, but I still think it's pretty neat.
Other than that, you can buy relatively inexpensive converter boxes that take composite video and analog audio, and output HDMI.
https://forums.atariage.com/topic/380883-unix99-a-unix-like-...
