Current events - Revision history

Winston at 18:10, 19 January 2013

2013-01-19T18:10:04Z

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			== New Spectranet firmware ==

			Spectranet firmware has been updated - the current version is labeled R544.

			Changes:
			* '''Streams module:''' Incorrect flags being set when creating a file (thanks Guesser)
			* '''Streams module:''' Now ensures a sane file mode is set when creating a file
			* '''Snapshot manager:''' No longer makes snapshots world writable when creating them (oops) on fileservers with POSIX permissions

			How to update your firmware:

			%mount 0, "vexed4.alioth.net"
			%load ""

			Choose "A..Firmware check/Update".

			[[User:Winston\|Winston]] 18:10, 19 January 2013 (UTC)

	== ZX Breakout ==		== ZX Breakout ==

Winston at 21:16, 16 October 2012

2012-10-16T21:16:49Z

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			== ZX Breakout ==

			There's a new mini-project: the ZX Breakout. This little board allows you to prototype your CPLD designs easily with either a Xilinx XC9572XL or an XC95144XL. It has header pins for all the ZX bus signals, as well as 39 GPIO pins from the CPLD routed to headers. Read about it on this page: [[ZX Breakout]]

			A batch of boards is currently being made, and should be back with me this week or early next week.

			This board was originally just going to be a level translator board so the user could prototype FPGA circuits (or other designs with 3.3v chips that were not 5v tolerant). However, to get the most from a new board I decided to use a 3.3 volt CPLD with 5v tolerant IO pins. This means it can be used as a level translator but also has a lot of added usefulness since it can be used to prototype the logic for other things, too. To give an idea of the logic resources available, the XC95144XL was used by Chris Smith to make an implementation of the Spectrum ULA, and the ULA uses all the resources of this chip - that's to say, the '144 gives you about the same resources that were available to designers using a Ferranti 6000 series ULA.

			[[User:Winston\|Winston]] 22:16, 16 October 2012 (BST)

	== Failure rates, regenerating clocks ==		== Failure rates, regenerating clocks ==

Winston at 17:12, 29 September 2012

2012-09-29T17:12:32Z

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			== Failure rates, regenerating clocks ==

			I'm going through my box of incomplete/to be reworked Spectranets. Enough people are after them that I want to make some available before the next batch is done. Out of interest, out of the failed ICs so far since I started doing this (from about 50 boards or so):

			5 duff flash ROMs (one died on a board I had been using for demos for some time)
			2 duff static RAMs
			1 duff W5100
			1 duff CPLD

			I thought originally there were 9 duff flash ROMs, but one board turned out to be in my rework box by mistake (there was absolutely nothing wrong with it), one turned out to be a very small solder bridge on the CPLD shorting the chip select pin that was going to the flash and the other two actually turned out to be the RAM that was duff. Fortunately, this means I don't have to change the PCB footprint for the flash chip - I did think this was causing poor solderability but apparently not. I don't like making changes to a proven design if I don't have to.

			The duff CPLD was actually my fault, it was one of the early boards (and it still sits in my rework box today...) - I accidentally connected Vcc and GND the wrong way around on my JTAG lead when preparing to program it. Not only did the CPLD die, smoke came pouring out of the +3's power supply. The duff W5100 was easy to spot - the chip started getting really hot the first time the board was plugged in. My intention is to keep the boards that are not in new condition for demos, and the rest which are in new condition to go over to Rich Mellor to fill in while the next batch is made. I should have 10 of them in new condition.

			Looking at some new project work, I've successfully made a digital PLL in Verilog which will regenerate the Spectrum's 3.5MHz clock, that's to say it generates a clock that is in sync with the /CLK signal at the edge connector, and keeps running during periods of contention. This is important if you want to accurately be able to count the number of T-states the ULA sees. This has been tested with a real Spartan-6 FPGA too, and it works! There's a discussion about it here: [http://www.worldofspectrum.org/forums/showthread.php?t=40885 World of Spectrum forums]

			[[User:Winston\|Winston]] 18:12, 29 September 2012 (BST)

	== Spectrum30 ==		== Spectrum30 ==

Winston at 21:39, 19 September 2012

2012-09-19T21:39:04Z

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			== Spectrum30 ==

			Just over a week ago, we had the Spectrum30 event organized by Thomas of Sintech (all the way from Germany!) It was an excellent event, with a numner of luminaries giving talks (including Rick Dickinson, Kevin Toms and Chris Smith).

			It also marked general availability of the Spectranet! Unfortunately, the latest boards have almost all sold out already. Fortunately, I will be getting more made :-) The Spectranet is available at the [http://www.sellmyretro.com/ Sell My Retro] site run by Rich Mellor of RWAP Software (he'll be handling all the sales side, as already mentioned).

			Secondly, I'm thinking of a new hardware project. Having got the Speccy online, we need to make sure it can continue to display on monitors and TVs for some time to come. I'm currently investigating the feasability of making a DVI-D interface for the Spectrum, which will work both for DVI monitors and televisions with HDMI inputs. Initially, I'll be looking to put out a 480p (640x480 resolution) signal to the display since it's standard and should be supported by everything - but I'll probably look into resolutions that won't cut off as much of top and bottom border when line-doubled. I've already got a Xilinx Spartan-6 development board to prototype this. It'll be much work, but probably less work than the Spectranet (much, MUCH less software required). The challenge will come with the high speed digital design aspects - the frequency of the TMDS outputs even at 480p resolution is pretty high. The development blog will appear here too.

			[[User:Winston\|Winston]] 22:39, 19 September 2012 (BST)

	== On sale at last? ==		== On sale at last? ==

Winston at 23:04, 3 September 2012

2012-09-03T23:04:09Z

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			== On sale at last? ==

			With a bit of luck, yes, you'll be able to buy a Spectranet at Spectrum30 ( http://spectrum30.org.uk ) in Cambridge this weekend! Rich Mellor of RWAP Software will be in charge of handling the sales.

			Also, you'll be able to play Spectank (see http://www.youtube.com/watch?v=6fEvuENABZY )

			In other news, there's been some last minute changes to the CPLD. One circuit that's not changed since the very first prototype CPLD is the memory paging circuits. These have been optimized and made much less complex - their initial complexity was really just an artifact of my inexperience with the CPLD and Xilinx ISE. Also, some improvements have been made to the programmable trap circuit. This circuit reads two bytes (to form the low and high halves of the address that must be trapped) using a single IO port. To control which register gets written to, there's basically a flip flop configured as a toggle. This gets reset on power-up or when the reset button is pushed, but very occasionally, the programmable trap would fail to work. I suspect there were some transient signals during the very slow rising reset signal that comes from the Spectrum, and occasionally this toggle could get flipped. Additionally, the timing was somewhat tight on when it toggled (basically the register that got filled relied on the propogation delay being sufficient within the CPLD), so the timing has been changed to be more robust - the toggle now switches on the 'leading edge' of the IO cycle instead of the trailing edge, so it will have been set several hundred nanoseconds before the Z80's write signal rises at the end of the cycle. And to add a belt and braces approach, software can also reset the toggle to guarantee its state will be known before writing to the register. The reset is performed simply by reading the IO port that is used to set the programmable trap (this read also returns the CPLD version, which is now updated to 0001 binary. The three versions are: floating bus = prototype, 0000 = first production batch which the early adopters got, and 0001 is the ones that have existed since last Saturday. The prototype is floating bus because it simply never had the version read circuit, and there are ten of them in the wild I can't have reprogrammed easily.

			[[User:Winston\|Winston]] 00:04, 4 September 2012 (BST)

	== The Raspberry Pi and the Spectranet ==		== The Raspberry Pi and the Spectranet ==

Winston at 21:42, 3 July 2012

2012-07-03T21:42:24Z

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			== The Raspberry Pi and the Spectranet ==

			[[Image:Spectranet-and-pi.jpg\|thumb\|right\|300px\|Raspberry Pi nestles amongst Spectranets at Imperica Horizons]]

			The Raspberry Pi promises to be a great companion to the venerable Spectrum when equipped with a Spectranet :-)

			I have just received mine from Farnell. I've gone and downloaded the SD card image for the Debian Squeeze distro, and put it on an SD card and gone and booted the little machine (just how The Creators Intended, using the composite out on the Pi to a CRT television...). The Pi comes with all the development stuff you need to build server applications. I've done some testing already with the TNFS (file server) program, and the Pi is now serving files perfectly to a Spectrum.

			I've also done a brief test of the Capture-the-Flag server (there's some bits of code which aren't necessarily terribly portable in the CTF game server), and so far indications are good that it's just a straightforward build to make it all work. I need to get another Speccy on the network to test it properly, though. All this should be on show at RetroEuskal in Bilbao later this month, and of course at the Cambridge Speccy 30th anniversary event in September, and later on at Replay Expo in Manchester.

			I intent to make some pre-built Debian packages (and a little Debian apt repository) for the Raspberry Pi programs. At the same time I'll do the same for x86 and amd64 based Debian systems.

			Incidentally, on the subject of shows, I should have written about it then - but the Imperica Horizons Speccy at 30 event in London was excellent, some very interesting people gave talks including Saul Metzinger, the director of "Micro Men" (who hung out with us later at the bar at the BFI). Videos and pictures are here: http://www.imperica.com/horizons (and of course there was a talk on the Spectranet!). Eben Upton was there too to present the Raspberry Pi, since we're talking about the Pi. I have a nice pic of one of the early models nestling amongst two Spectranets (as you can see!)

			[[User:Winston\|Winston]] 22:42, 3 July 2012 (BST)

	== Emulating the Spectranet ==		== Emulating the Spectranet ==

Winston at 10:42, 25 February 2012

2012-02-25T10:42:38Z

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			== Emulating the Spectranet ==

			The Fuse (Free Unix Spectrum Emulator) SVN trunk now includes Spectranet emulation - so if you don't have a Spectranet you can at least try it out emulated. You will have to build it from source, though, at the moment - so you'll need some kind of Unix-like development environment. It runs well on Mac OSX and Linux, and some brave souls have built it on Windows so far; if you ask in IRC on #spin you might find something out about that.

			To get the Fuse source, visit Sourceforge - [http://fuse-emulator.sourceforge.net/]

			Once you have Fuse running, you'll need to install the firmware and save an SZX snapshot with the firmware loaded - see this guide here: [http://fuse-emulator.svn.sourceforge.net/viewvc/fuse-emulator/trunk/fuse/hacking/spectranet.txt]

			[[User:Winston\|Winston]] 10:42, 25 February 2012 (UTC)

	== Delinquency ==		== Delinquency ==

Winston at 21:39, 14 January 2012

2012-01-14T21:39:13Z

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			== Delinquency ==

			OK - so I have been incredibly delinquent in writing any updates (a year!) But 2011 was fairly eventful, and other things in life kept me away from my projects. But the current update on the situation:

			* Production was sorted out! A fair number of Spectranets have been factory assembled. A number are in the hands of "early adopters" to shake out any bugs.
			* A manual is being written.
			* Many bugs have been fixed, thanks to early adopters.

			I hope to soon have details on how you can get your hands on one.

			[[User:Winston\|Winston]] 21:39, 14 January 2012 (UTC)

	== Perhaps production is sorted out.. ==		== Perhaps production is sorted out.. ==

Winston at 16:27, 16 January 2011

2011-01-16T16:27:40Z

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			== Perhaps production is sorted out.. ==

			Thanks to the Zonadepruebas Jupiter Ace project, I think I've found somewhere which will do the assembly of the Spectranet for a reasonable cost. At the moment the target date is the end of Feburary.

			Watch this space...

			[[User:Winston\|Winston]] 16:27, 16 January 2011 (GMT)

	== Argh! A hardware problem! ==		== Argh! A hardware problem! ==

Winston at 22:01, 6 December 2010

2010-12-06T22:01:04Z

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			== Argh! A hardware problem! ==

			So I'm almost done and I've discovered a hardware problem: there's a bug within the W5100 chip which means if the reset pulse arrives at the wrong time, it won't connect to a 100Mbps network (in other words the kind of network most people have). Of course I have about 30 of the chips with the bug already, it wasn't fixed by Wiznet until the end of 2009 or so, so it's only recently chips without the bug have been around.

			There is a solution but it requires changes to the PCB. It requires the W5100's reset line be controlled directly via the CPLD instead of using the Spectrum's reset signal, and it also requires that the LINK LED output from the W5100 be taken to the CPLD so that software can detect the interface state (unfortunately, the W5100 doesn't provide a register that shows the state of the PHY).

			As for the software, it's almost done. TNFS now has some simple back-off rules which means it works much better on a network with packet loss or where the server can't respond in a timely way (I modified a copy of the TNFS server to deliberately respond slowly and/or drop packets). Also all of the sources have been transistioned to use GNU binutils - most of the work I did while at Retromañía during the hours of keeping an eye on the Juegodromo.

			I now just need to find somewhere that'll do partial assembly of the PCBs. I think it can be quite cost effective to get the time-consuming-to-solder ICs put on the board, then I assemble the rest myself. If that doesn't work out, I'll change the flash chip to a PLCC for the next revision of the PCB which will save about 70% of the time if I construct the boards myself.

			[[User:Winston\|Winston]] 22:01, 6 December 2010 (GMT)

	== The last 10% that takes 90% of the time ==		== The last 10% that takes 90% of the time ==