• Please review our updated Terms and Rules here

Looking for a datasheet DEC T11 Cpu

eeguru said:
Forgive me, I haven't read the whole thread in detail (though I will now!). SPI is generally more extensible than EIA-232 and most controllers/cores have an EIA-232 mode. Unless you have a flash part or something else connected, why not do EIA-232 serial output directly with the SPI engine?
Click to expand...

Hum .. I am not sure what you are asking here.

The situation is simple, I need to attach an UART "any uart that would fit" to the T-11.

Now the second thing is "I want to build this stuff possibly with a set of components I already have here" ( literally in my boxes/etc. ) , I have experimented already with this MAX3100, it has the advantage that having SPI "is not particulary dependant on any CPU bus cycle" and also have advantage of a low pins count so I don't need to route a lot of signals to it.

I have a few UARTs around here but all of them would anyway require me to adapt/emulate a their access cycle with the T-11 one, still like in this case, there would be also to map the register in a way the RT-11 ( the OS ) wants to see it.

The T-11 is just a CPU, does not have any SPI or Uart core into it so you need to attach an external device for that.

The reason I need the RS232 port is because I need to attach it to a VT220 and/or some sort of that ( Hyperterminal for example ).

When I started this "T-11 project" the idea was really "something I could make it up in 2 weeks or so without the need to go to the shop and buy anything" ( already failed a bit in that :rolleyes: ) so about the CPLD choice it's really "I have this XC95108 I have to do everything with it".

I already used this MAX3100, I know how to program it/make it work, but I wasn't thinking in the beginning in actually made it become "an HW emulation" of the ODT console ( DL11 ? ) I was thinking more along the lines "well I could simply modify the SW in the few necessary points" but turns out that actually that is probably going to be MUCH harder than making the MAX3100 act as a DL11.

Now this XC95108 "is something but not that big" it's not an FPGA nor a Microcontroller so that also adds quite a bit of challenge, in fact I was "worried really much" that by adding a 16 bits register I was going to run out of resources ( cells ) but I am still in.

Fundamentally in this case I have to "transform" a read/write in a particular memory address into a send/receive or 16 serial bits to the MAX3100 while making the CPU wait as this is happening and I have to do it "with a bunch of gates and a few latches/flip-flops" I can't write a super-complex state machine or such because it's not going to fit into that CPLD and then in the end all this have to look like a simple memory read/write to the T-11.

I was already feeling quite sorry I had to increase that counter 2 more bits thinking "oh now this is going to steal me 2 more latches" :D

Ah I see now better what you are asking, you say basically "why not to make your own uart using the CPLD itself ?"

Because transmitting would not be too complex but receiving would be and again I don't think I have enough cells for doing it, SPI is "more or less" "an uart" but less complex I don't need any time sincronization cause I am giving the clock.

Keep in mind the XC95108 "is not a super big thing".
 
I already understand all of that. I looked at the specs for the XC95108 and I didn't see mention of a hardened SPI core. But at only 108 macro cells, it seems really small to do all you are doing with T11 interfacing and SPI clocking. However if you are doing SPI clocking in VHDL, why not do RS-232 disrectly with an external MAX323 or MAX211? What does the MAX3100+VHDL SPI module give you that a VHDL RS-232 module doesn't? (other than the baud rate generator - which you could fix with a pierce osc and fixed divider)

I don't mean to complicate things. Just trying to offer alternatives! If you are comfortable with the current design, go with it!
 
On a side note, RSX11M+ I think is the most knowledgeable person I've ever encountered on any one subject! You are a beast when it comes to PDP-11 knowledge. /bow
 
eeguru said:
I already understand all of that. I looked at the specs for the XC95108 and I didn't see mention of a hardened SPI core. But at only 108 macro cells, it seems really small to do all you are doing with T11 interfacing and SPI clocking. However if you are doing SPI clocking in VHDL, why not do RS-232 disrectly with an external MAX323 or MAX211? What does the MAX3100+VHDL SPI module give you that a VHDL RS-232 module doesn't? (other than the baud rate generator - which you could fix with a pierce osc and fixed divider)

I don't mean to complicate things. Just trying to offer alternatives! If you are comfortable with the current design, go with it!
Click to expand...

It gives :

- baud rate generator ( ok could be a fixed baudrate )
- interrupts
- the receiver has all the 16x sampling logic with proper detection of start/stop/cell and majortiy sample logic
- 8 words FIFO
- other things like irDA support and such

The point is it's a CPLD NOT and FPGA, I don't think there's really room to synthesize any RS232 module into it, as you saw that thing has only 108 macro cells you are doing stuff counting them almost on your fingers :)

Well an RS232 transmit module ok that could be easy, but a receive module I see it a bit more complex to squeeze in, plus I want the SPI so I can connect eventually in the future other SPI devices.

Even if I'd do the RS232 module myself, I am sure it would turn out "quite similar" to the problem/situation I am dealing now.

Actually "look it another way" this "SPI module" is kinda of a very simplified "RS232 module".
 
On another note I am just simulating/checking a bit all this stuff, there are some errors in that VHDL ( not of syntax but logic ) so in other words some stuff is not working but I am fixing it.

Told you I haven't tested it yet ...
 
GilesGoat said:
On another note I am just simulating/checking a bit all this stuff, there are some errors in that VHDL ( not of syntax but logic ) so in other words some stuff is not working but I am fixing it.

Told you I haven't tested it yet ...
Click to expand...
LOL - I admire your tenacity.

As for the SPI - I see that it serves the purpose and is "at hand". I also suspect you have other tools that make the choice practical.

I won't question it.

Making the SPI enough like a DL11 to work with the OS might be too ambitious at this point. Let's stop at ODT compatibility for now. That only requires TX/RX Data register addresses and one bit [RX Data Available] in the RX Status register.

We'll deal with Interrupts for RT-11 compatibility at another stage - OK?

Likewise, IDE based disk emulation can wait. Let's just see if ODT can interact with the console and memory, then re-examine what to do next. At that point you'll know you have a good memory system, working CPU and minimal I/O.

I know we discussed a PCB. If you're still heading this way, it looks to me like you're pretty much there once you're satisfied with the VHDL code.

Thanks for the compliment eeguru... means a lot coming from you. :blush:

I'll try to transition to your BLOG on this project, going forward.
 
Yes "one step at the time".

I need to "simulate" the "stretch" caused by the ready thing in my code to see what actually happens with the SPI.

But now 23:46 I am too tired to do that thing properly.

Yes once I am satisfied with the VHDL I'll begin routing the PCB.

Let's not forget, in all this, I still have not a clue if that T-11 chip actually works or not .. it could all end up in "nothing" ..

So far the few I tested ( rom/ram read/write ) theorectically should work, I am still working on the other thingies.

But not now this time of the night, at this time only weird bugs would come out.
 
As you may have noted ( or maybe not ) I made a "transition" from this thread to a blog to have a kind of "day by day history" of the progress of this stuff ( which is still going ).

Someone made my noted about the blog useage, now admittedly looks like "I see the way to use the blog in a different way" ( maybe I am confused/biased by the fact I was used to have a "livejournal" ).

So I am asking a bit of suggestion around here about "how you'd prefer to see things", in my opinon "a blog" is like "a diary" where you write stuff "as it comes" and it creates a kind of "sequential history" ( i.e. day X blah blah, day Y blah blah ).

But looks to me as someone is suggesting you'd rather prefer I'd start ONE blog entry with one topic like "The T-11 project" and continue commenting it by adding all and only what's relevant on it as a "stream of comments" so they day let's say I'd start another blog entry "The project Y" it will all be grouped as that.

If there is some sort of general consesus here about "how to use blogs" please let me know I'll try to organize/re-organize mine, I can try to simply re-edit all those topics and cut & paste them as "comments" under the T-11 one ( once I'll find how to do it ).

Please let me know what you find would be "better" and I'll do my best to re-organize things :)
 
I share your opinion of blog usage. However I'm not associated with the board maintainers... so. Personally I'd like to see the conversation continue here so it shows up in 'New Posts' :) My $.02
 
You must log in or register to reply here.
Back
Top