EEVblog #747 - PC Based Logic Analyser Project

[miguelvp]

I thought I was the only person left on the planet that did VAX assembly. 
The ultimate complex instruction set with instructions like MOVTUC, POLYD and ACBL

What did these instructions do?
How many were in the instruction set?

MOVTUC: Move Translated Until Character
moves a string from source to destination using a 256 entry translation table and will stop when the given character is encountered or either the source or destination string are done.
Both source and destination strings have lengths supplied.

POLYD: Polynomial Evaluation using D_Floating point format.
VAX supported 4 floating point formats of different sizes and exponents
F_floating 1 bit sign, 8 bits exponent (bias 127) 23 bits fraction (IEEE 754 single-precision float)

D_floating 1 bit sign, 8 bits exponent (bias 127) 55 bits fraction
(could be converted to F_float by discarding the last 32 bits, great for high precision calculations and then you could convert it to float for the final answer.

G_floating 1 bit sign, 11 bits exponent (bias 1023) 52 bits fraction (IEEE 754 double-precision float)

H_floating 1 bit sign, 15 bits exponent (bias 16383) 112 bits fraction

for the full description on what POLY did, look at page 322 of the linked doc.

ACBL: Add Compare and Branch (Long)
opcode limit.rx, add.rx, index.mx, displ.bw

limit is what to compare to, add is what to add to the index operand, displ is a sign-extended value for the jump when the comparison is greater than or equal to 0. Used for For and Do loops.

Here is the full VAX Instruction Set:
http://h20565.www2.hp.com/hpsc/doc/public/display?docId=emr_na-c04623178

But really I don't think it's of any use anymore, but it was a really powerful instruction set, RISC superseded it in the early 90s and the Alpha chip just put the last nails in the coffin.

Other than in college I've never used it since since all the coding was done in Fortran or C, in the meanwhile DEC was switching to MIPS processors for their DECStations, final end of life for VAX was on the year 2000.

I worked using VAX until 1995, by that time we replaced our 8600 for a Dec Alpha server, original cost of the 8600 probably was around half a million and we got about $10,000 trade in value (after about 10 years) for the Alpha server that sat in the same huge room with halon system and power conditioning on a raised floor.

But that 8600 could have over one hundred users connected and no one felt a hitch. Awesome machine!

[Len]

I thought I was the only person left on the planet that did VAX assembly. 
The ultimate complex instruction set with instructions like MOVTUC, POLYD and ACBL

What did these instructions do?
How many were in the instruction set?

Too much.
Too many.

It turned out that RISC CPUs with simpler instruction sets got higher performance because the hardware required to implement the VAX instruction set was so complex. And a compiler could produce faster code by ignoring some of the fancy instructions and using simpler ones. The CALLS procedure call instruction was a prime example of over-engineering.

I have many fond memories of using VAXes, but they had the Ford Expedition of instruction sets.

[Carl_Smith]

The ultimate complex instruction set with instructions like MOVTUC, POLYD and ACBL

The best assembly language mnemonic is from the PowerPC, called Enforce In Order Execution of I/O, written as EIEIO.

[SL4P]

And the best assembly language (instruction set) for a long time was the PDP-11 family!!
Consistent addressing modes, all sorts of easy to remember functionality.

[kizzap]

Ignoring all the programming arguements, I have to note one thing:

It looks like the power input you have there has no protection what-so-ever 

No fuse, no EMI filters? Not even a Power switch? (unless the Power input is a combination device of some sort.)

-kizzap

[SL4P]

Well, it was a long time ago... declared as a rough and ready prototype... (With lashings of elec insulation tape!)
Apart from the transformer primary and technician's fingers, there isn't much more to protect I'm that plastic case !'

[st]

Does this look familiar at all?

Built this way back when I was still in school and Dave was _not famous_.
Didn't remember at all he had anything to do with it, but it's been sitting on my shelf all of those years.

Thought it would be fun to show this on the forum rather than just the youtube comment.

Should I keep this until it is worth as much as an Apple 1, or should I sell it on Ebay? ;-)

ST

[RupertGo]

For those who enjoy reliving the Coding Wars, the BBC ran a short series last month on Radio 4 about the cultural history of various programming languages called Codes That Changed The World. They're all available here http://www.bbc.co.uk/programmes/b05qqhqp/broadcasts/2015/04, I think indefinitely, with no region block.

(oblig. disclaimer: I was involved in making these)

[Wim_L]

Pascal was a terrible language. Fundamentally broken: http://www.lysator.liu.se/c/bwk-on-pascal.html

Pascal was specifically designed for teaching. It intentionally lacked features that caused inexperienced new programmers to develop hard to debug problems. It should be judged in that context. It was neither terrible nor fundamentally broken. It should be judged in terms of how well it met its original intended purpose.

Kernighans comments are about how Pascal is unsuitable as a systems programming language are perfectly well considered. And in doing so he entirely avoids highly opinionated value judgements like "terrible" and "fundamentally broken".

Also take into account that the criticism was of standard Pascal at the time. The proprietary extended Pascal languages (like Turbo Pascal) had ways to get past some of the limitations of standard Pascal, at the cost of becoming harder to port to other compilers.

[mcs_5]

See J.R. Stockton's page for more details and patches that might help.

There are also TSRs that "fix" the problem without patching executables or recompiling the code. I use r200fix written by Veit Kannegieser (available here: http://hobbes.nmsu.edu/download/pub/dos/r200fix.zip).

My PCB software, accounting software and probably other stuff has the r200 problem...

[vkirov]

Are there any analogs for those LSI chips? I realy want to build this thing just for hobby purposes.

[PKTKS]

I have seen Dave's  project...

And I do have some half dozens schematics and boards
from that time period too.

Mostly are obsolete but they are part of my stuff.

I have already found the FREE AUTOTRAX version released from ALTIUM.
Fine it works good enough under DOSBox.

But I can not find the companion SCHEDIT  set with libraries so to view
my schematics too in original format.

If anyone can help by pointing any  loadable usable version...

That would be very helpful to have my stuff back.

Thank you very much  any help welcome.
Paul