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VIDC Enhancer boards |
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Paul Vernon |
Message #120300, posted by PaulV at 15:40, 9/5/2012 |
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Hi All,
Based on the information on Charlie's website and also on RISCOS.org, I've designed and had professionally manufactured a small run of VIDC Enhancer boards (with a twist).
My design also includes a SYNC on GREEN fix that allows you to remove the CSYNC signal from the video output when the Archimedes is configured to output separate H & VSYNC signals by way of changing a jumper rather than cutting a pin or track on the Arc itself which is the recommended way of doing things on RISCOS.org. This issue affects the A300, A400 and A400/1 series machines so I figured it'd be worth building into the board.
I've designed the board so that it can be used as a straight VIDC Enhancer or with the SYNC on GREEN fix installed too so it should be equally at home in an A3000 as the SYNC on GREEN problem doesn't exist in that machine 
Anyway, the boards have arrived back from manufacture today and other parts are on order (most parts should arrive tomorrow but the oscillators are on back order and should arrive late May) so I was just wondering if anyone would be interested in buying one when they're completed?
http://www.retro-kit.co.uk/user/custom/Acorn/3rdParty/RetroKit/VIDCEnhancer/VIDCEnhancer-large.jpg
Paul |
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Jon Abbott |
Message #120301, posted by sirbod at 16:09, 9/5/2012, in reply to message #120300 |
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Count me in, you going to put them up on eBay so we can buy them? |
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Paul Vernon |
Message #120302, posted by PaulV at 17:12, 9/5/2012, in reply to message #120301 |
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The plan is that once the parts are all here, I'll build up the common bits and then finish off each board depending on how it needs to be configured for each person that wants one because the SYNC on GREEN fix requires a different chip fitted at IC1 depending on it being an A300, A400 or A400/1.
If I don't get much take up from direct sales, I'll make up a few of each config and put them on ebay to try and recoup the costs of having the boards and oscillators made to my specifications that way. If I can get away with avoiding ebay that would be great as I can pass on the cost saving from not having to pay so many transaction/advertising fees to people but if I do end up selling some on ebay, so be it.
I'm not keen on exceeding 36MHz clock speeds for the enhancer (although Charlie has taken his up to 50MHz) as that would require people to start looking at cooling solutions for the VIDC chip but these days, 36MHz oscillators are like hens teeth so I had to order them specially hence they're on back order from the manufacturer direct...
Also, I should add for the A300, A400 and A400/1 series there is definitely a requirement for some soldering (and optional soldering on the A3000). IMO soldering is preferable to track cutting which would be the alternative method of installation.
If someone wants an Enhancer but can't solder or isn't confident about it then I'll be offering that service too.
Paul |
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Charlie |
Message #120311, posted by Charlie at 23:04, 9/5/2012, in reply to message #120302 |
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Fantastic!
Properly made hardware. I hope you get lots of interest.
Yes, 36Mhz crystals are a swine to get hold of. If memory serves my only option was to order a bunch of them - all used in my own VIDC enhancers and other projects I'm afraid...
...all the more reason for peeps to snap these up while they may.
Paul, I don't know if you've heard of a retro computer trading site called Amibay? It's run by and for enthusiasts. In spite of the name all formats are welcome. It's another potential outlet for your VIDC enhancers, where you can be pretty sure they will go to a good home. |
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Steffen Huber |
Message #120321, posted by hubersn at 12:29, 10/5/2012, in reply to message #120311 |
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Yes, 36Mhz crystals are a swine to get hold of. If memory serves my only option was to order a bunch of them - all used in my own VIDC enhancers and other projects I'm afraid...
...all the more reason for peeps to snap these up while they may.
My favourite electronics mailorder shop (www.reichelt.de) still lists 36 MHz oscillators:
http://www.reichelt.de/Oszillatoren/OSZI-36-000000/3//index.html?ACTION=3&GROUPID=3174&ARTICLE=13705&SHOW=1&START=0&OFFSET=500&&SID=252WmySawQARkAACfoEIE96d99c5c87cb48d28bd043a712e26ac4&LANGUAGE=EN
Shipping costs are quite expensive to the UK though. |
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Paul Vernon |
Message #120324, posted by PaulV at 12:57, 10/5/2012, in reply to message #120311 |
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Thanks Charlie I've been trying to find a way to contact you off list but I can't find a way. Could you contact me via my website http://www.retro-kit.co.uk/page.cfm/content/Contact/ so I don't have to give out my e-mail address unnecessarily to the web
Thanks
Paul |
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Paul Vernon |
Message #120325, posted by PaulV at 13:01, 10/5/2012, in reply to message #120321 |
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Oh I wish I'd known about that! Still, I'll have enough Oscillators to build plenty of boards,carry spares and have a surplus which will be going on ebay to recoup some of the cost...
Paul |
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Paul Vernon |
Message #120349, posted by PaulV at 03:15, 11/5/2012, in reply to message #120302 |
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Whilst I'm waiting for the oscillators to arrive, I've tested the SYNC on Green fix and managed to figure out a set of prices for different configurations and levels of parts for the boards so hopefully it should suit everyone's pocket.
Configurations and costs are here:
http://www.retro-kit.co.uk/page.cfm/content/VIDC-Enhancer/#costs
Current progress on the build and testing is here:
http://www.retro-kit.co.uk/page.cfm/content/VIDC-Enhancer/#build
Paul |
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Paul Vernon |
Message #120350, posted by PaulV at 03:15, 11/5/2012, in reply to message #120302 |
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Whilst I'm waiting for the oscillators to arrive, I've tested the SYNC on Green fix and managed to figure out a set of prices for different configurations and levels of parts for the boards so hopefully it should suit everyone's pocket.
Configurations and costs are here:
http://www.retro-kit.co.uk/page.cfm/content/VIDC-Enhancer/#costs
Current progress on the build and testing is here:
http://www.retro-kit.co.uk/page.cfm/content/VIDC-Enhancer/#build
Paul |
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Jon Abbott |
Message #120353, posted by sirbod at 08:44, 11/5/2012, in reply to message #120350 |
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Sounds reasonable pricing considering the time/effort you've put into this.
Explain the software control part though. |
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Paul Vernon |
Message #120355, posted by PaulV at 12:21, 11/5/2012, in reply to message #120353 |
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The board is essentially a modified version of the board designed by Andreas Barth that was published in the mid-90's which you can find out about here: http://www.riscos.org/legacy/vidc.html it was also streamlined and reduced in size by Charlie who has a project page covering building your own board here http://grope.thruhere.net/Qube/projects/vidcenhancer.html.
As such, my design will be compatible with the software control module written for that board but it adds the SYNC on Green fix onto the board too which allows you to switch between the original 15KHz monitors and VGA type monitors simply by changing a jumper setting rather than cutting pins or tracks on the motherboard which I've detailed here:
http://www.retro-kit.co.uk/page.cfm/content/Modifying-an-Archimedes-A4101-to-use-a-VGA-monitor/
How software control works:
Essentially, the software sits in memory and looks at the mode choice when changed. It has a lookup table that tells it when it should activate the VIDC Enhancer board and when it doesn't need to. This is executed by way of setting the Aux1 pin on the motherboard high or low. If you look at the board design, the four pin connector marked CN2 is used to control this feature. Pin 1 is connected to the Aux1 pin on the motherboard, Pin 2 is electrically connected to pin 1. Pin 4 is always 5V. Pin 3 therefore will either be 0V (off) or 5V (on) depending on the current set up of the board and whether Aux1 is high or low.
Using a on - off - on rocker switch to choose between pin 2 and pin 4 connecting to pin 3, the full manual control can be effected allowing you to set the board to SW control, off or on respectively.
The software control only version simply does away with the rocker switch 3 spade connectors and wiring to suit, and replaces it all with a single jumper that connects pin 2 and pin 3, fixing the board into software control mode. This means that you can't switch the VIDC Enhancer off or permanently on in this configuration without opening up the Arc and changing the jumper. There is no difference to the board itself and if you want to provide your own switch, cabling and connectors then you can do so at a later date.
Many VIDC Enhancers that were created BITD didn't have the manual control options and only used software control but adding the switch allows you to effectively return the Arc to its original configuration without re-opening the machine and changing the jumper settings.
As a simple example, when connected to a VGA capable monitor that isn't a full multi-sync, Arc's typically operate in modes 27 and 28 which can happily occur using the original oscillator. When mode 15 is selected (for a game for instance), the screen is displayed but is "letter-boxed" with an incorrect aspect ratio. If a VIDC Enhancer is fitted and is under software control, it is activated at the point of mode change and due to the extra bandwidth VIDC1a can then provide, it is able to provide mode 15 at full height correcting the letter boxing issue.
Paul |
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Charlie |
Message #120360, posted by Charlie at 20:51, 11/5/2012, in reply to message #120355 |
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Hi Paul,
Loooong message left. 
I've just had a look @ your page for this project - very cleaver!
You may already know; apart from the software Andreas wrote our VIDC enhancers should work with any software that uses the same switching line. If memory serves that includes Atomwide's and Beebug's versions, along with a few 3rd party utilities.
TBH: Having tried a few I still prefer Andreas' software for its simplicity, but Atomwide's may have the edge if you run in to pitch issues on sound output - if memory servers their software has some built-in compensation.
I have one of WE's SuperVIDC enhancers: Supposedly more like the A5000 as it carries 25 and 36Mhz crystals. At one point I was going to reverse-engineer it for the projects page (may still do some day) but I dislike the software so much it's days in my A3000 are numbered. It's controlled by the I2C in it's own way rather than being a 'proper' A5000-alike - a pity. Some day (maybe) I'll have a go at a 'proper' A5000 VIDC clone: Plug in, switch on, job done.
You've prompted me to have a closer look @ my A420/1 motherboard: It's a flaky beast (some day I'll have the time to work out why) but in it's favour doesn't have the sync on green issue...
...I wonder if there's more than one revision of this motherboard / a previous owner fixed it and I just didn't notice / I've been lucky.
I think I'll go have a look now. |
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Paul Vernon |
Message #120365, posted by PaulV at 01:18, 12/5/2012, in reply to message #120360 |
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Hi Charlie,
No message here if you mean you dropped me a line?
Thanks for your kind words I had an inkling that other VIDC software would work with it but was going to wait until I'd got my board fully built up and tested before I went mad with testing other software
Putting two oscillators on a design would require two control lines so the existing software wouldn't work. I guess that'd give me a reason to unleash my Desktop C development environment and get to know RISC OS a bit better though  .
One thing occurs to me, how much hardware uses Aux1 AND Aux2? The more lines that a VIDC Enhancer used, the more chance there is for incompatibility with other hardware :-(
As far as I'm aware the A400/1 series is the same motherboard from the 410/1 through to the 440/1 and again AFAIK, there was only one issue so it sounds like yours has been "fixed" by either a track cut or pin 3 on IC9 being cut. Do you ever connect it to a 15KHz monitor or only to VGA monitors? what are LK1 and LK2 set as? If they're North and Closed respectively then the machine is set up for separate Vertical and Horizontal Sync signals so it's likely in that case that it has been "fixed" to remove the SYNC signal on the Green component.
My entire approach when creating this board was to do the least amount of work to the motherboard and where possible, avoid any mechanical changes such as cutting tracks. I know my design requires the removal of a chip and replacement with a socket but I see this as less invasive than cutting tracks on the PCB. At least with my design, it can be removed and the original board will still function without the need for "repairs" I've tried to be as sympathetic as possible to the original design.
Paul |
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Charlie |
Message #120368, posted by Charlie at 18:44, 12/5/2012, in reply to message #120365 |
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Having had a look I've still no idea why my A4** seems to work fine - I'll take a careful look @ the jumpers when I have a mo'. All my 'retro' computers are hooked up to TFTs, there's an AK85 lurking in the garage for emergencies.
Hmm SuperVIDC enhancer,
Some day I'll have a closer look @ the A5000 schematic and try to work out how Acorn did it (24, 25, 36Mhz switchable for A5000). I'd like to clone that system as it would hopefully require no software...
...I guess there's three ways:
-Use AUX1&2 - I'm not aware of a reason for not doing that and one could control three crystals.
-Use the I2C bus like the WE 'Super'VIDC to control it
-Pulse AUX1 (or two) and use a latch the count the pulses
I think I'll go have a look at the A5000 schematic now. |
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Paul Vernon |
Message #120369, posted by PaulV at 21:24, 12/5/2012, in reply to message #120368 |
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Having had a look I've still no idea why my A4** seems to work fine I guess it could be your monitor. In so far as it may actually not care that the SYNC on Green signal is there and simply ignore the SYNC but keep the Green part of the signal after all, some monitors are less fussy than others.
All I know is that my CRT AKF50 and Samsung Syncmaster together with my Iiyama ProLite's *all* ignore the Green signal completely :-/
Use AUX1&2 - I'm not aware of a reason for not doing that and one could control three crystals. Three *extra* crystals 24MHz on the motherboard, then 25.175MHz, 36MHz plus a crystal to over clock the VIDC chip... Hmmm now that would be interesting I'm breaking out the logic tables right now, although I'm pretty sure a multiplexer would be required to control the output clock signal choice.
In fact I've just checked and on the A540/R260 motherboard, Acorn use the 74ACT153 mux to do just that to select between the 24M, 25.175M and 36M lines... Sheet 2/5 on the A500R200 service manual technical drawings.
Paul |
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Paul Vernon |
Message #120544, posted by PaulV at 18:51, 7/6/2012, in reply to message #120350 |
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Just a quick update to this thread.
As those who've been keeping up will be aware, I've been waiting for the oscillators to arrive and I'm pleased to say that they arrived this morning. To that end, I've now completed one board and been testing it out in my A410/1.
Everything seems to be working just fine and I can now run 800x600 @ 16 colours without my LCD monitor complaining that the signal is out of range
The final step now is to wire in the Aux pin for software control but I'll be doing that at the weekend.
I thought that you'd appreciate an update and a link to a reasonably high-res photo of the finished board.
http://www.retro-kit.co.uk/user/custom/Acorn/3rdParty/RetroKit/VIDCEnhancer/VIDCEnhancer-Fully-populated-PermanentlyOn-lge.jpg
Paul |
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Paul Vernon |
Message #120570, posted by PaulV at 01:28, 12/6/2012, in reply to message #120544 |
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... and as a follow up to the VIDC Enhancer board configured for the big box Archimedes, here's a high-res shot of the board configured for software control only and fitted to my A3000...
http://www.retro-kit.co.uk/user/custom/Acorn/3rdParty/RetroKit/VIDCEnhancer/A3000-software-control-lge.jpg
I'm not going to recommend fitting the board in this configuration as it is only compatible with earlier motherboards. The non-riser configuration is going to be better for the A3000 and I'll be building a test version of that config tomorrow
Paul |
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Jon Abbott |
Message #120641, posted by sirbod at 15:47, 19/6/2012, in reply to message #120300 |
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Are these available yet? I've finally managed to source an A440/1 and could do with a VIDC board. |
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Paul Vernon |
Message #120642, posted by PaulV at 17:42, 19/6/2012, in reply to message #120641 |
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Almost! I've been working on writing a full manual for them which is almost complete. As I don't own an A300 or A400, I've arranged to get hold of one at the weekend so I can confirm the instructions for that particular motherboard design.
As for the 400/1 series and A3000, I've fitted a board to each of my own machines and they're working a treat.
The draft manual is available on the link below and it should give you an idea of what you'll be getting.
http://www.retro-kit.co.uk/user/custom/Acorn/3rdParty/RetroKit/VIDCEnhancer/manuals/VIDC-Enhancer-manual.zip
Paul |
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Jon Abbott |
Message #120643, posted by sirbod at 18:24, 19/6/2012, in reply to message #120642 |
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Manual...you mean it's not plug and play |
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Paul Vernon |
Message #120646, posted by PaulV at 23:00, 19/6/2012, in reply to message #120643 |
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LOL Not quite plug and play, the closest to that is the A3000 install which is just a case of opening the case, connecting it up and configuring the motherboard jumpers before closing it up again. That is as close to a traditional VIDC Enhancer as it gets with my particular design
The big box Arcs are a little more involved but worth it I think.
Besides, I'm a very visual person so the manual is full of photo's showing key installation points which I hope illustrate the process well.
Once installed it is totally transparent to the system and the effect it has on the system can be undone through the setting of jumpers so it doesn't ever need to be unplugged
Paul |
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Paul Vernon |
Message #120723, posted by PaulV at 02:45, 29/6/2012, in reply to message #120369 |
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I've managed to make the VIDC board design in such a way that two can be plugged in together and provide 25.175MHz and 36MHz in addition to the 24MHz VIDCclk signal.
This was a completely unintended consequence of designing the board on a riser but a rather welcome result.
After hacking the original AutoVIDC module code around a bit, I'm happy to report that it works a treat
http://www.retro-kit.co.uk/page.cfm/content/Dual-VIDC-Enhancer/
Paul |
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Paul Dunning |
Message #120724, posted by hairydalek at 10:40, 29/6/2012, in reply to message #120723 |
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This is testament to the design of the Acorn systems - whether intentional or not, it’s amazing that 25 years on, my A305 machine can happily run an LCD screen with this modification fitted - and I’d class it as a fairly minor board modification. What was truly astounding (to me, anyway) is that once fitted, it’s software controlled, and it just works.
All on a system designed in the early/mid 1980s which, had it come from anywhere else, would no doubt need contemporary display hardware to function.
I am working my way through my A305’s hard drive, finding stuff I had forgotten about (drawings mostly), stuff I had fun with (games, bits of a magazine I ran at uni, my font design projects and essays) and stuff which I’m going to have a ceremonies mass deletion (all my post uni job application letters are on it). Using an 800x600 resolution makes me wonder how I coped with 640x480 (and lower). |
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rob andrews |
Message #120725, posted by microbits at 10:50, 29/6/2012, in reply to message #120724 |
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Now all you need to do is softload 3.5 to give you outline fonts in the desktop and get rid of the system fonts. |
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Peter Howkins |
Message #120726, posted by flibble at 12:02, 29/6/2012, in reply to message #120725 |
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Now all you need to do is softload 3.5 to give you outline fonts in the desktop and get rid of the system fonts. Well the 'universal boot' works on 3.1 and gives the outline font manager.
I wrote a little program a while back to make it easier to pick fonts on 3.1 as it's missing the options from !Configure.
http://www.marutan.net/download/riscos/config2.txt
http://www.marutan.net/arcsite/down.php#riscos |
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Paul Vernon |
Message #120727, posted by PaulV at 13:56, 29/6/2012, in reply to message #120726 |
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Ooh, that looks interesting. Having a screen res that needs a better font is a minor pain but if it can be sorted it'll be worth a look.
I assume though that it's really only suitable for older machines with an ARM3 upgrade. Outline fonts are CPU intensive on the Arc IIRC.
Paul |
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Andrew Rawnsley |
Message #120728, posted by arawnsley at 14:38, 29/6/2012, in reply to message #120727 |
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Once the fonts are cached, it should be usable on ARM2/250 systems. If I recall, I had it working on my A3000 which never had the ARM3 upgrade.
Of course, you wouldn't want sub-pixel AA on, but I think that was off by default on older OS versions anyway. Once cached, the standard fonts should be fine. You'd probably want to *configure about 64-128Kb of Font Cache.
PS, I'd be buying one of these enhancers, but last time I tried my A3k, it simply wouldn't power on. I suspect it needs some PSU soldering attention, but I've never found time to sit down with it and do diagnostics 
[Edited by arawnsley at 14:39, 29/6/2012] |
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Paul Vernon |
Message #120729, posted by PaulV at 16:11, 29/6/2012, in reply to message #120728 |
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Thanks for the extra info on the Fonts.
I've got a spare A3000 PSU that is working (but not refurbed) if you want it for the price of postage. It's the none caged type so you'd need to source that fire proof surround for it if you don't have one of that type but if it is OK for you, the offer is there.
Paul |
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Paul Vernon |
Message #120730, posted by PaulV at 16:11, 29/6/2012, in reply to message #120728 |
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EDIT: double posted so I removed this one...
[Edited by PaulV at 16:12, 29/6/2012] |
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Paul Vernon |
Message #121838, posted by PaulV at 16:12, 29/1/2013, in reply to message #120369 |
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I've just received a new batch of VIDC Enhancer boards and I've based the design on the discussion Charlie and I had above last May.
I've built it so that it can carry up to three on-board oscillators and it accepts the Arc's original 24Mhz clock too so you can have the best of all worlds with full A540/A5000 video mode capabilities AND the ability to over-clock VIDC for higher resolutions if you so wish.
The boards arrived this morning and I've built one up for testing purposes. At this stage, it's fitted to my A310 and looks great
http://www.retro-kit.co.uk/Ultra-VIDC-Enhancer/
I'd also like to thank Jon Abbott and Steve Harrison who have encouraged me and pointed me in the right direction at times when I've been working on getting a new version of AutoVIDC sorted so that it can provide all the functionality needed to support the new VIDC Enhancer.
I'll be releasing the software shortly via my site but to summarise, it is now officially registered with ROOL and provides an SWI to allow programmers to set the VIDC clock frequency as required amongst other bits and pieces.
As a bonus, the new module should still be compatible with standard single VIDC Enhancers that use Aux IO for control too
Paul |
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