The 9900 address up to 65,536 bytes of memory

[Sinphaltimus]

Where is our 65k consoles?

 

Or is it 32k for ram and 32k for other (carts/roms/groms/etc).

[Sinphaltimus]

Ok nevermind. Page 58:

 

Before memory expansion the TI-99/4a console includes a little over 8K bytes of CPU Memory, 16K bytes of VDP RAM, and 18K bytes of GROM, for a total of 42K bytes. A fully expanded system could address 128K-64K bytes of CPU Memory, plus 16K VDP RAM, plus 48K of GROM.

 

Fundamentals of TI-99-4a Assembly language

Edited September 4, 2016 by Sinphaltimus

[Sinphaltimus]

I'll keep thus thread active with my Assembly questions.

[+mizapf]

Where is our 65k consoles?

 

64 KiB, to be precise: https://en.wikipedia.org/wiki/Binary_prefix

 

Having an address space of 64 KiB does not mean having memory of that size. Your 64 bit PC has an address space of 256 terabyte (48-bit address bus), which is 65536 times larger than a 4 GiB memory.

 

A fully expanded system could address 128K - 64K bytes of CPU Memory, plus 16K VDP RAM, plus 48K of GROM.

 

This is the typical TI nonsense, or let's call it, a creatively disguised semi-truth-lie. The 9900 can address 65536 bytes, none more or less. Counting GROM and VDP memory to the addressable memory - although they are stream-read via a single address - is not really honest. That way, you could add SAMS memory or even floppy disk space to it.

 

It already started at the beginning when they claimed their console had 16 KiB of memory, which was just video RAM, or rather the remaining bytes after putting bytes aside for the screen tables. But you could not really win anything by telling that the console only has 256 bytes of RAM and 16 KiB of VRAM that is largely used for BASIC programs (by inhibiting the bitmap graphics mode).

Edited September 4, 2016 by mizapf

[Sinphaltimus]

Yeah, that sounds strange to me so I'm guessing it was to keep production cost down since cpu ram was so expensive at the time. And uneducated guess at that

[+mizapf]

Well, if you intended to sell a computer system that is targeted at the home user with BASIC programming skills, to expand it with modules, and to get your money from the professional programmer who needs assembly language ... then TI's decision was actually good.

 

Sometimes one may wonder whether there was no consideration about competition with other systems; even the VIC-20 of that same time had more directly accessible memory than the TI console, and it was foreseeable that its successor will offer even more. Was it this kind of blindness that we call "Betriebsblindheit" in German ("professional blindness", "business blindness", "operational blindness")? There is no better concept/system than ours?

[Sinphaltimus]

"Willful Ignorance"?

[+mizapf]

Not really willfulness, but being unable to imagine a weakness in one's conception.

[+Ksarul]

Group-think. Once the idea takes hold, it is the only idea, and the group is now incapable of objectively evaluating it against any other competing idea.

[Tursi]

It's worth noting that at the time of its design, the TMS9918 was one of the cheapest ways of getting 16k of memory into a computer on the market, because it used DRAMs /and/ had the DRAM controller integrated. I've read a number of articles where other designers were really tempted by that feature alone. Since TI envisioned GPL being the primary development environment, they didn't really care whether it was CPU RAM or not. Since the initial design was for a game system, again, a small amount of CPU RAM wasn't unusual. The Vic20 didn't come out till 1980, how was Texas Instruments supposed to know in 1978 (or earlier, but since the 99/4 came out in 1979 it must have been designed earlier) what its specifications were going to be?

 

We like to say "why didn't they do better than "competitor"?", often forgetting that competitor came out /after/. The competition for the 99/4 resembled this (discounting large systems, the Altair 8080, and similar kits):

 

Apple 2 - 1977 - 6502 CPU @ 1MHz, 4KB RAM

Atari 2600 - 1977 - 6507 CPU @ 1MHz, 128 bytes RAM

Commodore PET - 1977 - 6502 @ 1MHz, 4KB or 8KB RAM

Tandy TRS-80 - 1977 - Z80 @ 1.7MHz, 4KB RAM

 

The Atari 400 and 800 came out the same year as the 99/4, everything else came out later. But versus those specifications:

 

TI-99/4 - 1979 - 9900 @ 3MHz, 16KB RAM -- sounds pretty impressive from a marketing standpoint. And since GPL made accessing VDP largely equivalent to CPU memory anyway, on paper the plan probably looked fantastic. And like you note Mizapf, TI largely intended to market through cartridges, which is well supported by this plan.

Edited September 4, 2016 by Tursi

[+mizapf]

You're right, the 99/4 preceded the VIC-20 by a year, one should not be too unfair, and I guess changes from /4 to /4A were limited (9918 -> 9918A, keyboard, ROM). Crystal balls were similarly expensive in those days. Was there such a secrecy around upcoming architectures? Today you hear about developments some years earlier ... maybe because there are much more dependencies and contributions which you cannot really keep secret nowadays.

[palmheads]

Plus when TI changed tack, & released modules like the mini-memory - even though that had only 4KB ram, the unexpanded VIC-20 was something like 3.5KB. Lots of cassette games were made for the unexpanded VIC (Gridrunner etc). That could have been a more successful market if TI has maybe introduced the mini-memory a year or so earlier than they did.

[sometimes99er]

Where is our 65k consoles?

 

Or is it 32k for ram and 32k for other (carts/roms/groms/etc).

http://www.unige.ch/medecine/nouspikel/ti99/architec.htm

 

Nouspikel's TI-99/4A Tech Pages. This is the one.

[Retrospect]

I thought the 9900 cpu came natively from a minicomputer or mainframe, which in those days having 256 bytes of RAM for the CPU was commonplace. They would have found a very cheap option to not increase the CPU ram and use the VDP to store your BASIC programs. Hey it would have been great if the CPU had even 16K to address but would have put up the price by at least 100 dollars // pounds which would have proved prohibitive as it was an expensive machine to make in the 1st place.

[+mizapf]

Plus when TI changed tack, & released modules like the mini-memory - even though that had only 4KB ram, the unexpanded VIC-20 was something like 3.5KB. Lots of cassette games were made for the unexpanded VIC (Gridrunner etc). That could have been a more successful market if TI has maybe introduced the mini-memory a year or so earlier than they did.

 

I would have first argued that TI was just too expensive. We recently had a thread about "Prices in the 80s" (http://atariage.com/forums/topic/256446-prices-in-the-80s/ ) showing Minimem at about DM 300,- in 1984 (about $120,-).

 

But another peek into my archive showed that a complete VIC-20 was priced at DM 595,- in 1983 ($233,-), and I just found an ad for the C64 in 1983 at about DM 1395,- ($550,-). That is, Commodore was not really cheap at this time either, but prices fell quickly in the following years.

[JamesD]

I thought the 9900 cpu came natively from a minicomputer or mainframe, which in those days having 256 bytes of RAM for the CPU was commonplace. They would have found a very cheap option to not increase the CPU ram and use the VDP to store your BASIC programs. Hey it would have been great if the CPU had even 16K to address but would have put up the price by at least 100 dollars // pounds which would have proved prohibitive as it was an expensive machine to make in the 1st place.

The minicomputers had plenty of RAM by the late 70s. They ran compilers and multiple applications at once.

At least one version of the 990 minicomputers used multiple blocks of 64K.

Even single board hobbyist computers came with 1K in the mid 70s.

S-100 or SS-50 buss machines usually had 4K or more.

 

[Willsy]

The TI's 256 bytes of RAM is more akin to a "console" than a full-blown "computer" IMO. Like TI expected the majority of folk to run software on cartridge, which normally wouldn't need much RAM. And of course, if you do need RAM, there's plenty of video RAM! (yack!)

[Sinphaltimus]

I'm having so much fun with the TI that I can't help think "..with just a little more ram..." so yeah, I keep poking and proding the topic but I think I have my answer now.

[JamesD]

The machine should have had a 32K word (64K) of RAM internal upgrade with the ability to turn off the ROMs for all RAM+I/O, and BASIC should have had PEEK and POKE.
TI might have been able to stay in the personal computer business.

[+Lee Stewart]

The machine should have had a 32K word (64K) of RAM internal upgrade with the ability to turn off the ROMs for all RAM+I/O, and BASIC should have had PEEK and POKE.

TI might have been able to stay in the personal computer business.

 

Actually, both TI Extended Basic and TI Basic have PEEK and POKE. PEEK is CALL PEEK and POKE is CALL LOAD. TI Basic does only have those functions with the Editor/Assembler cartridge inserted or with user loaded versions of them.

 

...lee

[sometimes99er]

Actually, both TI Extended Basic and TI Basic have PEEK and POKE. PEEK is CALL PEEK and POKE is CALL LOAD. TI Basic does only have those functions with the Editor/Assembler cartridge inserted or with user loaded versions of them.

 

...lee

 

TI Basic in itself did not have PEEK and POKE. You'd have to insert a relatively expensive cartridge to get there. "Breaking the sandbox" aka running assembler (to maybe have PEEK and POKE) with the unexpanded console was only discovered in this millennium.

 

[Tursi]

In addition, no software change would have affected the cost to build the machine, which was already too high for TI to swallow. As for the hardware suggestion, the concept of banking out the ROMs to add more RAM space didn't hit the home computer market until the C64 some 12-13 years later! TI clearly felt they had plenty of memory space to waste, giving a full 8k space to 4 peripherals (one of which wasn't even released at the time, and each of which only actually needed 4 address ports ). 32k of RAM (or 48k to the marketing folks) clearly felt like enough to them at the time.

 

The 99/8 looked a lot like it was going to solve most of the issues we most complain about, it was designed much later and with the benefit of competition. But, of course, it was too late before it even came out. I know I was really excited about it though.

[Retrospect]

How much more would it have cost TI, and in the end the consumer, if the machine had been equipped with 32K in the first place, and the ability to poke and peek? .... I remember my cousin telling me at the time the reason people were buying Spectrums and even Vic-20's was down to the fact that you had to buy a RAM upgrade to do anything like that.

[+mizapf]

Remember that PEEKing and POKEing had different effects and use cases for the architectures. That is, the C64 exposed much more to the BASIC user than the TI, in particular the video memory, vital BASIC pointers etc.

[JamesD]

 

TI Basic in itself did not have PEEK and POKE. You'd have to insert a relatively expensive cartridge to get there. "Breaking the sandbox" aka running assembler (to maybe have PEEK and POKE) with the unexpanded console was only discovered in this millennium.

 

And there definitely wasn't a USR() function call.

 

In addition, no software change would have affected the cost to build the machine, which was already too high for TI to swallow. As for the hardware suggestion, the concept of banking out the ROMs to add more RAM space didn't hit the home computer market until the C64 some 12-13 years later! TI clearly felt they had plenty of memory space to waste, giving a full 8k space to 4 peripherals (one of which wasn't even released at the time, and each of which only actually needed 4 address ports ). 32k of RAM (or 48k to the marketing folks) clearly felt like enough to them at the time.

 

The 99/8 looked a lot like it was going to solve most of the issues we most complain about, it was designed much later and with the benefit of competition. But, of course, it was too late before it even came out. I know I was really excited about it though.

Sorry, but the Apple II used the Language Card to bank out it's ROMs for RAM in 1979, and the CoCo 1 also did this in about 1981.

The Apple II also had a ROM card then let you use Integer BASIC ROMs in the II+, but the language card was more flexible.

The language card was built onto the motherboard of many clones like the Franklin Ace 1000, and it was standard on the IIe.

While Tandy didn't directly support the RAM banking feature at first (they didn't even support 32K at first), it appears that the Motorola SAM chip was designed for that type of memory map. It didn't include the actual RAM switch internally though. The first 32K RAM CoCos actually had 64K of RAM.

 

The C64 came out in 82 and the TI-99 came out in 79.. How is that 12-13 years later? Or did you mean 2-3 years later?

Given the release date of the Apple II language card though, it's a moot point.

 

Edited September 6, 2016 by JamesD