Pipelined 6502/z80 with cache and 16x clock multiplier

I remember the blinkenlight envy problem when I built my first homebrew in the late 70's. It was a Southwest Technical Products 6800 system. It actually had a monitor that allowed you to communicate through a terminal instead of depending on switches and lights.

For a terminal I had a TV Typewriter system.

One of my first printers was an IBM Selectric to which I added a kit to convert serial data to solenoid pulls. That was used to type an MS thesis in 1978.

Mark Borgerson

I can vouch for the longevity of railroad relays. I worked for a railroad one summer as a signalman's apprentice helper... talk about the bottom of the ladder... We maintained the signals and such. I remember the relays with glass bottoms so you could inspect the contacts. They had a slip of paper filled out with the date put in service, the date last maintained and the names of the people who did it. These things weren't quite 100 years old, but some were as much as 60 and had not been opened for the last 20 years!

Partly this is because of the low duty cycle. They were only activated a dozen or two each day which even after 20 years is only five digits. Every transistor in my PC does that many switches in a fraction of a second.

It was a very different time though. In those days, when you put your name on something you wanted it to show how good you were. Just like the initials on the bottom of the gas tank on my old BMW motorcycle. The tanks would run down the assembly line and ladies hand painted the pin strips on the tank. They put their initials on the bottom, a different one on each side. Do you know of any cars, trucks or motorcycles that are initialed by the people who do the work anymore?

I like to think I have that work ethic. But there are often realities that don't let me do the quality of work I would prefer. Deadlines are always paramount! Customers don't like failures, but they don't like missed schedules either.

Rickcc

One ham friend of mine wrote an ascii to morse code driver in an eprom. He used it for error messages and dumps to verify that his keyed in code was correct.

Those good old days weren't so good. I donated my old computers to a computer museum a few months ago. I was surprised that an old OSI I built booted up after more than 25 years setting on a shelf.

Regards,

w..

-- Walter Banks Byte Craft Limited

+--------------- | Mark Borgerson wrote: | > I remember the blinkenlight envy problem when I built | > my first homebrew in the late 70's. ... | > One of my first printers was an IBM Selectric to which | > I added a kit to convert serial data to solenoid pulls. | > That was used to type an MS thesis in 1978. | | One ham friend of mine wrote an ascii to morse code | driver in an eprom. He used it for error messages and | dumps to verify that his keyed in code was correct. +---------------

I once connected a small loudspeaker to the "Zero Balance" console light of an IBM 1410 CPU, producing a click each time an arithmetic operation had a zero result (or a comparison tested "equal"). The resulting "music" gave a most illuminating view into the progress of the currently-running program, e.g., a long "BZZZZZ..." whenever the operating system was waiting for the printer to be put on-line, which was loud enough to alert the operators lounging in the break room down the hall. [The printer was left off-line when not in active use, since that decreased the IBM maintenance charges!!]

Another useful case was a peculiar repetitive "squishing" sound when running a large, multivariate nonlinear regression, that got faster and faster as the regression approach convergence. That sound allowed the statisticians waiting for their results to make a rough guess as to how much longer the calculation would continue.

[Of course, we had to disconnect it before each visit from IBM Field Service, to avoid getting in trouble!]

-Rob

----- Rob Warnock

627 26th Avenue San Mateo, CA 94403 (650)572-2607

In comp.arch Rob Warnock wrote: [...computers with loudspeakers...]

Like many other sites, we just used to keep a radio on the console table of the KI-10.

After about 1 hr of self-programming, you could tell what mood the thing was in without having to scan the 100s and 100s of panels with

100s and 100s of little globes for patterns.

The daily accounting job had its distinctive rumbles around 8am (if you were one of those that lived across the road from the college and walked in to see what the big blue boxes were up to before 9am and the accouting was running late). Something to do with a massive (10 MB!) external sort needed to get the accouting records into order in only 64kw of memory (25% of the available h/w).

If the daily job failed you could hear a bunch of squeaks and were ready for the diagnostic that printed out a min later.

--
[A]s a Conservative, I have no tolerance for ambiguity.
  -- BONZO@27-32-240-172.static.tpgi.com.au [>70 nyms and counting], 14 Jan 2011
14:46 +1100

The ICT/L 1900s used an ASR-33 as the console, but it was modified to have a small loudspeaker and volume control at the right end of the front face.

The speaker was connected to the V (overflow) bit & made the usual noises.

In the installation where I worked during University vacations, when the operators started a long job, they would phone their rest room (N.B. NOT "restroom" 8-), and leave the handset by the speaker. They would then retire for a tea break and a bit of knitting (they were all women), picking up the rest room phone from time to time to check whether the job had terminated.

--
Bill Findlay
with blueyonder.co.uk;
use  surname & forename;

A similar thing was already built-in in the British Elliott 803 computer in the console, of early 1960's vintage. The speaker was connected to the MS bit of the instruction register. As the basic instruction cycle was 288 us, the sounds gave pretty good indication of the progress of the processing.

--

Tauno Voipio

But the AVR8 is a core, that gets included in an ASIC (Application- Specific Integrated Circuit) fabricated on an FPGA (Field-Programmable Gate Array).

Would there be a market for such a thing as a discrete chip? That's more debatable. Certainly, since increasing the word size and arithmetic capabilities is a more efficient optimization for general computing than cache and pipelining, which are applied later, the application would need to be one that didn't benefit from longer than

8-bit arithmetic.

John Savard

Well, they simply adopted a desperate strategy to make a 16-bit processor with a general-register architecture possible with the minimum number of transistors on the chip itself. As soon as more transistors on the chip would become possible, _of course_ that would no longer be needed.

John Savard

From what I remember, that series of was a micro version of an earlier TI Mini (ttl ssi etc) and the memory based register idea was not that bad in an era where the performance of most minis was underwhelming, to say the least. I thought it was quite a neat idea at the time, but the only contact I had with them was for an avionics bite processor as it was one of the few micros of the time which was qualified rad hard.

Absolute performance is not the issue - If it gets the jab done to spec, it's fast enough :-)...

Regards,

Chris

The TMS-9900 was a single chip version of the TI-990 minis, and thus inherited many of the architectural quirks of its predecessors, just like the relatively contemporary 9440, IMP-4 and 6100 did (and later chips like the LSI-11 did as well). How desperate this was, I don't know, but the 9900 was one of the first 16 bit micros.

Obviously saving transistors in the core was an issue whether the core was implemented with a pile of TTL (as were the early 990's), or in the severely constrained VLSI processes of 1976 (the 9900 shipped a full two years before the 8086). But in 1976, external memory was still very expensive (~$50*/KB raw, several times that vendor supplied and installed in the minis or mainframes of the era) and 64KB was a lot for a small machine. Memory was also fairly fast relative to the CPU, making the concept reasonable (this is the same time when Apple ran main memory at double the CPU's rate so they could run the video output on half of those cycles).

Of course a few years later the 16 bit minis got smacked from both sides as architectural limits pushed people to their 32 bit replacements at the high end, and the growing power of the micros at the low end (IIRC, the original 9900 shipped as a .33MHz part =96 yes a third of a megahertz, and the fastest instructions ran in as few as eight cycles).

*1976 dollars. Adjusted for inflation, about $190 now.

TI making the TMS9900 family had nothing to do with "desperation". It was simply an LSI version of the TI-990 minicomputer, much like the LSI-11 being DEC's chip level implementation of their PDP-11 minicomputer.

The reason the TI computers didn't have internal registers was because at the time it was conceived, CPU speed was limited by the speed of memory and when TI started making memory chips to replace slow magnetic core memory, it only made sense to utilize main memory based workspaces rather than a tiny register set on the CPU chip. What diminished the utility of this approach was not the number of transistors, but the speeds that ultimately were obtained that could not be duplicated going off chip. That is the same reason why CPU makers ultimately started incorporating cache memory on the CPU die rather than using off chip fast, static RAM. Before it became viable to include the cache on the CPU die, they made CPU modules that included RAM chips along with a CPU packaged to minimize the speed penalty of going between chips. But ultimately this was a major limiting factor in CPU clock rates and had to go.

Now we find that the only real speed limiting factor is the software. Today's CPUs run DOS so fast that a user can't fully utilize the capabilities. As for memory, who would ever need more than 640 KB anyway? That is why the GUI was invented. It makes the computer more easily used by the masses, but more importantly it sucks up all available CPU speed and memory capacity to continue to create demand for ever faster CPUs which are sold along with... new software!!! Good thing food vendors haven't figured out this approach to sales... oh, wait, they have... "Can I Super-Size that for you sir?"

Rick

Huh?

The 9900 came first.

Then they built the 990/4 which was powered by a 9900.

Later on, they built a souped-up LSI version, the 990/10, and even later another version came out with a floating-point capability that wasn't made available at first.

John Savard

t

The 990/9 was made in 1973. Later when the 9900 chip was available the made the 990/4 using it. See

[snip]

I remember an announcment from TI stating that later 990 Minis actually cached the registers on chip (when you changed the workspace register it did a writeback of "dirty" registers). Their claim was that the result was just as fast as the typical on-chip registers, but they got to maintain backward compatibility.

My big disappointment was their personal computer (TI-99?), they wrote an interpreter that was used to implement an interpreter for Basic, and they didn't provide peek/poke or machine language function calls, so you were

*forced* to use the slow basic interpreter for everything.

The design of the 9900 was very elegant in many respects (the I/O was pretty neat as well, at least it had a low pin count even if it wasn't very fast). They just didn't want to make the leap to 32 or 64 bits with it. When they introduced the TI 99000 you could almost here the collective Doh! throughout the industry.

- Tim

data,

ine.

pecs.

Do you think this low investment in quality is due to the ever- shortening product life cycles? And that business model tends more and more to encouraging turnover/upgrades? This also seems to explain why consumer product user interfaces (e.g. cellphones) are so awful and getting worse.

t

The C certainly wasn't full C. I think the Pascal was a subset (no recursion, iirc?) To get full blown languages you needed a Tube system

- my school had a nice Z80 CP/M Tube BBC clone with an integrated colour screen.

It was excellent; I used it for years (and heavily exercised that assembler).

I never saw these. Where would you get them today? (Apple recently pulled their FTP site which formerly hosted MPW, but not these tools, unless they were in a directory apart from the main distribution.)

I used TML Pascal in the 1980s for Macintosh. Nice environment but Lightspeed (later THINK then Symantec) Pascal and Lightspeed C eventually killed off the competition :)

Even though I programmed the 990/4, I don't recall ever even seeing a magazine advertisement for the 990/9. I had no idea that such a machine existed, although I knew of at least one of the 960 or the 980 as incompatible antecedents to the 990.

John Savard

Yes, this was ridiculous. They didn't want to have to cut prices on the 990 "minis", and they therefore didn't have an ethos of providing maximum performance at minimum cost.

John Savard