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101090 discussions

FPGA I/O and external memory (was Re: CDC 6600 emulation - was Re: How do they make Verilog code for unknown ICs?)

by spacewar＠gmail.com

On Mon, Jun 20, 2016 at 10:07 PM, ben <bfranchuk at jetnet.ab.ca> wrote: > Do you use Static or Dynamic ram with the FPGA's? I've done both. You indicated that you wanted 5V I/O. AFAIK, there haven't been any new FPGAs made in many years that have even 5V-tolerant I/O, let alone actual 5V I/O. Some really old FPGAs may still be in production, but are not very cost-effective. The latest midrange to high-end FPGAs aren't even 3.3V-tolerant. However, the economy FPGAs such as Spartan 6 and Artix 7 still support 3.3V I/O, and are quite inexpensive for the amount of resources provided. For 5V-tolerance, it is usually adequate to use 3.3V I/O with series resistors to limit the current. Xilinx specifies a maximum rated current for the clamp diodes. This works fine when interfacing actual TTL (or TTL-compatible MOS) parts. It is NOT adequate for driving 5V CMOS, such as CD4000 series, because the FPGA won't drive above 3.3V, and the 5V CMOS inputs typically are specified for Vih min of 90% of Vdd, which is 4.5V. The series resistor does slow down the signal, which usually isn't a problem with TTL since TTL is quite slow by FPGA standards. Where it is a problem, an nFET voltage clamp can be used instead.

10 years, 1 month

How do they make Verilog code for unknown ICs?

by wkt＠tuhs.org

All, I messed around with VHDL last year. I found this a great book to learn VHDL best practices: http://www.gstitt.ece.ufl.edu/courses/eel4712/labs/free_range_vhdl.pdf The book is free but you can also buy a printed copy at http://freerangefactory.org/ I started with GHDL: https://www.fpgarelated.com/showarticle/20.php and then progressed to a Nexys4 FPGA board. Lots of fun. Just a few more resources to add to the mix. Cheers, Warren P.S The CPU I built with it: http://minnie.tuhs.org/Programs/UcodeCPU/index.html

10 years, 1 month

NetBooting old MacOS 8.x or 7x.

by swiftgriggs＠gmail.com

Due to the news about the MacOS name change, it's becoming quite hard to Google for older MacOS stuff. Was it ever possible to netboot MacOS 8.1 or earlier? I have A/UX 3 running nicely on a Quadra 700, now, but now I want to dual boot it with MacOS, but I don't have a CDROM. Taking out the drive and putting it on my other 68k Mac (a Centris 660AV) and installing MacOS still gives me some weird issues that I suspect are related to having installed it on different hardware. If I can't do a network based install, I'll probably just steal a longer SCSI cable, use a molex power splitter to add another 5V power cable, and then install from CDROM while the system is half-open. Then I'll just button it up afterwards. The factor SCSI cable in my Quadra 700 has only one connector for a drive. -Swift

10 years, 1 month

General *NIX ramble thread - was Re: Quadra 660AV what's with the "PowerPC" label?

by ian.finder＠gmail.com

Changing thread title and invoking filter. Thanks, - Ian On Mon, Jun 20, 2016 at 10:50 AM, Swift Griggs <swiftgriggs at gmail.com> wrote: > > And yet, now that significant chunks of the Linux underpinnings are > > being combined into one purpose-written close-knit chunk, designed by a > > single team, the same sort of people that praise *BSD for its conceptual > > unity are harshly damning the thing bringing comparable unity to Linux. > > Odd, that. > > It's not the same thing, IMO. People aren't slamming Linux+systemd for > unifying their team (I've not even seen the harshest systemd critics > mention this even in passing). They aren't upset because of the greater > "conceptual unity", either. They are upset because it's breaking faith > with "the unix way" (creating a giant all-consuming mega-daemon with > equally heinous binary opaque supporting-crap ala journald) and going > their own way (a hard right toward Bloatville with a couple of stops near > Lake Clueless if you ask me), and they are, in the opinion of many, being > jerks with the implementation of their planned schism. > > -Swift > > -- Ian Finder (206) 395-MIPS ian.finder at gmail.com

10 years, 1 month

DL11 M7800

by jnc＠mercury.lcs.mit.edu

> From: Paul Birkel >> I will upload the content to the CHW (and add the DB9 pinouts, too). > Yes, please. OK, done; see: http://gunkies.org/wiki/DEC_asynchronous_serial_line_pinout and it references the new: http://gunkies.org/wiki/EIA_RS-232_serial_line_interface I'd be grateful for any feedback on how I can improve the page(s) - more data to add, thinks to explain better, etc. Note: I added the DB9 pinouts, _but_ I have never made an actual DEC->DB9 cable, and am unlikely to (see below), so these have not been experimentally tested. I'm pretty sure they're right (I checked them against some online tables), but 'the difference between theory and practise', etc, etc. So if someone does make any DB9 cables from this page, and can confirm that they works, I'd be very grateful! :-) I personally don't recommend making DEC->DB9 cables. DB25P<->DB9S adaptors are cheap and easy to find on eBay, and if you make everything DB25, all you'll need are a few DB25P<->DB9S adaptors to connect to PCs, and all your other cabling activity (e.g. connecting one PDP-11 to another) will be simple, since everything will be standardized on DB25s; no having to keep two kinds of every cable. Noel

10 years, 1 month

Eckert - Faster, Faster; books in general

by thebri＠gmail.com

Is there an electronic copy of this floating around? My (ex-library) copy is missing all of chapter 11, "What is there to calculate?. (And the last page of the previous chapter). The pages weren't ripped out, they were missing when it was bound. Very annoying, I enjoyed the book right up until it crashed, so to speak. Two, also ex-library, copies are listed on Amazon, and I hesitate to get another copy with the same problem. There are others, of course, at outrageous prices. Or maybe I don't realize the significance of '1st edition, not ex-library'. Just to make any discussion a bit more interesting, what would you suggest along similar lines? The two giant books on IBM (detailing "pre-360", and "360") were quite fun too. bri

10 years, 1 month

Monitor refresh rate query

by jnc＠mercury.lcs.mit.edu

> I'm puzzled as to how one could drive both interlaced and > non-interlaced monitors off the same video signal - wouldn't the > interlaced one need a video signal which has 'odd lines, then a > vertical retrace, then even lines, then a vertical retrace'? So to sort of answer my own question, interlaced and non-interlaced video signals are indeed different. It turn out that 1024x768 was defined by IBM as XGA, and it was originally an interlaced format - although a non- interlaced version was done later. So my laptop quite possibly really is producing interlaced video... Although how a monitor is supposed to tell whether a signal is interlaced, or non-interlaced, is not clear - there's certainly no pin on the VGA connector which says so! :-) > Anyway, so which one is the one which is the number to look at when > considering if the refresh rate is so high it might be dangerous to an > old CRT monitor? > E.g. my HP M50 manual says "Setting the screen resolution/refresh rate > combination higher than 1024x768 at 60 Hz can damage the display." Since the monitor I'm using is called an "Ultra VGA 1024", I'm going to assume it can handle 1042x768, and just stop worrying about it... If it melts down the monitor, it melts down the monitor! :-) > From: Jochen Kunz > Sounds like an interlaced video mode. No surprise that the LCD can't do > this. Yes, as soon as I realized it probably really was interlaced video, it became obvious why none of my LCD monitors would display it. Noel

10 years, 1 month

Any extra DEC monitors in Europe?

by useddec＠gmail.com

I have a friend looking for 2 DEC VRC21-KA monitors in Europe. I have one here, but will pack it only as a last resort. If you have one of two you want to sell or trade, please let me know off list. Also where you are located. Thanks, Paul

10 years, 1 month

Monitor refresh rate query

by jnc＠mercury.lcs.mit.edu

So I'm using an old (very old! :-) laptop for a console for some of my computers. The built-in screen on it is this miserable 800x600 thing (I said it was _old_ :-), so I'm trying to hook up an old 15" display (of which I have tons) and run it at 1024x768 at least (the highest resolution the old display hardware in the laptop will support). However... The first couple of LCD's I plugged in, they worked fine, but when I went to change from 800x600 to 1024x768, I got error messages about 'can't handle that display format' (or words to that effect). Nothing about what parameter was out of bounds, alas. Finally I found one that _did_ give me the numbers, and it said the retrace was 35.6 Khz / 44 Hz. OK, looking at some specs, it makes sense those LCD monitors didn't work - 44 Hz vertical retrace (which I gather is the same as the refresh rate, in things like 1024x768/60Hz - sorry about the newbiesh questions, but I want to make sure I'm not making a bad assumption) is _below_ the input specs on them. (Although why the refresh rate on an _LCD_ would have a lower bound that high doesn't make sense to me - so the screen updates less often, what's the problem? It's not like a CRT, where it could cause flicker.) So I finally found an old CRT monitor that worked - but now I have another problem! It reports the video as being 35.6 Khz / 87 Hz! Which makes me worry, because I'm not sure that particular monitor can handle an 87 Hz refresh. (Parenthetically, what exactly is the mechanism that causes damage if you run an old CRT monitor at too high a refresh rate? I assume the excessive speed generates too much heat somewhere, and causes transistors to fail, or something like that?) Anyway, back to the monitor - I'm wondering if that monitor is reporting a bad number on the vertical retrace, and in fact it actually is 44 Hz? Because I found this equation to calulate the vertical retrace frequency from i) the horizontal retrace frequency, and ii) the number of lines. So I plug 35.6 Khz (which agrees with the other monitor, note) and 768 into that formula, and get... 44 Hz! So is there some bizarre interlace mode, or something, that could legitimately cause confusion over the vertical retrace? Or is the second monitor just confused? I tried to look up the video controller chip (a Cirrus CL-GD 7543 'Viking'), to see if it could even _do_ 88 Hz, but I was unable to find any documentation about it online. Also, if it really is 44 Hz, can anyone point me at an old LCD display that will handle that? (The CRT I'm currently using - another one that supposedly handles up to 100 Hz vertical retrace - takes up too much room! And there's no point getting something new - and larger - since the machine won't do anything past 1024x768 anyway.) Noel

10 years, 1 month

The Great TK revival

by rodsmallwood52＠btinternet.com

Hi The great TK revival continues apace. There's a TK50 in my VAX 4000 running really well. Purrs like a cat I have TK70 in the RT-11 (11/83 QED) Machine that also runs. TK70 should read the TK50 tapes. It tries but complains about cant read the directory. So whats a common format I can write on a TK50 tape in a TK50 Drive (VMS) then take it over to the RT-11 box and have it read it.? Where is all this going? Well I need to end up with RSTS on an 11/83. So a bootable TK50 with RSTS install files on it is the goal. Meanwhile transfer by tape is useful. Rod

10 years, 1 month

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