[sdiy] Chip ID

[Batz Goodfortune]

Y-ellow Magnus 'n' all.
         Yes indeed the 8250 is the nat-semi beast. A dual UART in fact. 
Didn't they call them DARTs? I thought it was that intel also had an 8250 
which caused the confusion but upon checking this is not so. What I was 
thinking of was the 8253/54. In that although they're a different beast 
entirely there were two chips with basically the same functioning but two 
numbers apart. For anyone actually interested in this hysterical ranting. 
Err Sorry. HISTORICAL ranting, they are counter timer chips. Basically 3 
counter/timers per chip. The original PC XT/AT's had all of the above.

Err not the 8255. Damnit!

These were all 8 bit chips designed for 8bit systems. And just before all 
the Moto-heads out there start laughing, Motorola did exactly the same with 
the 68K at the time too. Tell me again how they're all 16 bit machines again?

I never really thought about how the legacy actually goes all the way back 
to the 4004. That's funny when I think about it because it's so true. Intel 
would never officially admit this but when they were developing the 8086, 
it was simply meant to be a faster 8085. (8 Bit). But Motorola were due to 
release a 16 bit processor so they kinda changed their plans mid stream. My 
guess is that they were too far down the track to an 8 bit and had no time 
to assemble a new team to throw together anything that would rival motorola.

So when you look at the architecture of the 8088/86 it looks strangely like 
an 8 bit processor with tacked on bits. Which is essentially what it is. 
The instruction set is remarkably similar. Everything. This is why the 
stupid thing can only see a 64K window at a time and has that God awful 
segmented addressing. All legacies which we are still dealing with to this 
day. Motorola had a contiguous address space and kicked ass from a machine 
code point of view. Although it had other issues which were just as insane.

8089 I/O co processor:
I actually had a machine which used an 8089 co-pro as well as an 8087 math 
co-pro. In fact I had 3 of them. Made by AWA and were designed to be used 
as multi-drop servers. Essentially diskless work stations. Though there was 
provision for 2 drives. Kicked ass in their day I guess although it wasn't 
"In their day" when I acquired them. But interesting to see the 8089 in 
action. Actually they had a slot for a second one as well. Dunno what they 
used that for. Probably disk I/O if they had disks? Anyway. A great many 
people would often lament the fact that provision for the 8089 was not 
included in the architecture of the PC. And "Bob" knows it could have done 
with one.


At 04:13 PM 5/4/02 +0200, Magnus Danielson wrote:

>The 6502 was two steps forward and one step back. The 8008 has more
>registers, six data registers and one accumulator. The 8008 doesn't
>tick as quick as the 6502, which formidably stands still by todays
>preferences.

Well, I was only trying to put a date on it by mentioning the 6502 but 
since we're here... The 6502 was supposed to be a souped up version of 
Motorola's 6800. The 6802 was motorola's own slight improvement on that. 
The zilog Z80 was born from a bunch of disgruntled intel engineers who 
thought they could do better than intel's 8080. And they did. While the 
6502 was stripped down and fast, the Z80 was scaled up and fast. And right 
there we have the birth of both RISC and CISC, and of the concept of "The 
Motorola architecture" VS "The Intel architecture." Processors that strayed 
too far from either path tended to have limited life spans. I think because 
if your processor didn't have adequate support chips available to it, then 
it's use was limited.

The irony of all this is that these legacies dog us to this day. From the 
Itanium to the latest G4 PPCs. Even though none of them use any of the 
legacy peripheral chips. Along the way there have been some truly awesome 
architectures but no-one's putting them on the desk top because the world 
has been so neatly divided into two camps. Where there was once a fair 
diversity in processors, you really only have a choice of 2. Especially now 
that MIPS is being side-lined and the StrongARM has found a niche in the 
PDA market. And of course, they held a funeral for the DEC ALPHA a few 
years ago. Burial at sea I think?

Of course, Linux runs on everything. Well almost everything. I had trouble 
running it on my abacus but the Babbage engine runs fine. Though I had to 
convert the boiler to gas recently. Wood and coal are getting expensive. 
Hey. It might be slow and noisy but it makes a good cappuccino.

Be absolutely Icebox.

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