Re: Jack Tramiel failed to save Atari.

On Oct 31, 10:49 am, Bruce Tomlin <bruce#fanboy....@[EMAIL PROTECTED]
> wrote:
> In article <1193828008.996379.17...@[EMAIL PROTECTED]
>,
>
>  "winston19842...@[EMAIL PROTECTED]
" <winston19842...@[EMAIL PROTECTED]
> wrote:
> > TI always had a penchant for making their own products look bad...
> > But you are right - the TI-99 wouldn't have been 16-bit if the TMS9985
> > microprocessor had been a success. It failed, so they had to stick in
> > a huge 9900, with static RAM chips to provide memory (the 9985 had an
> > on-board 256 byte cache, like the later 9995) and added logic (a
> > demultiplexer to interface with 8-bit peripherals) and added wait
> > states that REALLY slowed the 9900 down.
>
> That wasn't a cache.
>
> Those 256 bytes were the only RAM on the CPU bus, and were necessary
> because the 9900 put most of its registers in RAM. Everything else had
> to go through the VDP interface to use its RAM (which would be
> fragmented and rather limited if you used its highest-resolution modes),
> and which was quite slow, especially during non-retrace when video was
> being displayed. (I know a lot about the 9928 from having done some
> Colecovision programming in the past few years.)


It was a "register cache", a place to store the "software" registers.
The 9995 also did instruction pipelining (9985? maybe).