Atom upgrade pics as promised.

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
Post Reply
Prime
Posts: 2747
Joined: Sun May 31, 2009 11:52 pm
Contact:

Atom upgrade pics as promised.

Post by Prime » Sat Sep 04, 2010 8:09 pm

Ok First up is the Ram / Rombox board
IMG_1764.JPG
Atom memory upgrades.
IMG_1764.JPG (2.83 MiB) Viewed 1204 times
This adds 32K of ram maxing out the bottom half of the memory map, plus a rombox (in the flash rom), holding up to 16 4K extension roms, and optionially also holding the system rom.

The jumpers allow the mapping out of the $0A00 block for campatibility with the disk interface, the mapping of the to 4K of ram as either rom box bank 0 or as the top 4K of normal ram (at $7000), and the enabling or disabling of the dos rom withing the flash rom. These can also be over-ridden by writing to location $BFFE.

Left is the bare board, center is the assembled board, and right is the prototype for comparison.
IMG_1766 - cropped.JPG
Ram board in atom
IMG_1766 - cropped.JPG (783.8 KiB) Viewed 1180 times
This is how the board fits in the Atom, as you can see I have removed all the base ram 2114s, pluse the two system roms. This really helps as the 32K RAM chip, flash and CPLD will use much less power than the 2114s.....
IMG_1769.JPG
Atom prototype colour board
IMG_1769.JPG (2.37 MiB) Viewed 1177 times
Ok this is one of the things I'm working on at the moment, a modern replacement for the Atom Colour card, which unlike the Acorn original uses just 2 chips and a bunch of descretes, the main chip being the LMH1251 (mounted on the carrier board). As this is a 24 pin TSSOP, the final board should be quite small, though it is a little fidly to solder :)

Also note that unlike the Acorn card (and incidentally the Dragon 32 / 64), no attempt is made to alter the frame sync to 50Hz, but I figure that this is less of a problem these days, as most monitors / TVs can cope with this. Also this is RGB only, as adding colour composite video would make the circuit much more complex, and RGB is better quality in any case :)
IMG_1771 - cropped.JPG
Colour frogger !
IMG_1771 - cropped.JPG (465.77 KiB) Viewed 1183 times
Finally, a picture of the above playing frogger :)

Cheers.

Phill.
Last edited by Prime on Sat Sep 04, 2010 8:42 pm, edited 2 times in total.

User avatar
ukretrogamer
Posts: 432
Joined: Mon Nov 09, 2009 8:55 pm
Location: England's largest town
Contact:

Re: Atom upgrade pics as promised.

Post by ukretrogamer » Sat Sep 04, 2010 8:24 pm

I want one, I want one, I...

Per-lease? [-o< [-o< [-o<

Prime
Posts: 2747
Joined: Sun May 31, 2009 11:52 pm
Contact:

Re: Atom upgrade pics as promised.

Post by Prime » Sat Sep 04, 2010 8:34 pm

ukretrogamer wrote:I want one, I want one, I...

Per-lease? [-o< [-o< [-o<
Well I do have a couple of spare boards PM me if you want one made up cost will be about £25, will have to re-calculate as the boards ended up being cheaper to make than I origianally estimated, also depends if you already have ram chip (the board can take either a 0.3" or a 0.6" 32K ram. Note, FERAM does NOT seem to work :(

Also want to make sure that Charlie / Sirmorris doesn't have any problems with his first :)

Cheers.

Phill.

User avatar
BeebMaster
Posts: 2787
Joined: Sun Aug 02, 2009 4:59 pm
Location: Lost in the BeebVault!
Contact:

Re: Atom upgrade pics as promised.

Post by BeebMaster » Sun Sep 05, 2010 11:52 am

These are really exciting, although my personal favourite is "Atom prototype colour board", somehow it looks a bit more Atomy than the rest!

What's the official line on the unexpanded Atom being able to do colour, by the way? I think I talked to some of the Atom boffins at Bletchley about this because Atomic Theory & Practice is very misleading in my opinion about being able to get colour without buying a colour board. It appears to suggest that you can type in a load of assembler to do direct graphics plotting and then get colour, without having to have the Floating Point ROM with the COLOUR command. However I think this method only gives you greyscales and not actual techni-colour.
Image

Prime
Posts: 2747
Joined: Sun May 31, 2009 11:52 pm
Contact:

Re: Atom upgrade pics as promised.

Post by Prime » Sun Sep 05, 2010 3:12 pm

BeebMaster wrote:These are really exciting, although my personal favourite is "Atom prototype colour board", somehow it looks a bit more Atomy than the rest!

What's the official line on the unexpanded Atom being able to do colour, by the way? I think I talked to some of the Atom boffins at Bletchley about this because Atomic Theory & Practice is very misleading in my opinion about being able to get colour without buying a colour board. It appears to suggest that you can type in a load of assembler to do direct graphics plotting and then get colour, without having to have the Floating Point ROM with the COLOUR command. However I think this method only gives you greyscales and not actual techni-colour.
Well there's two sides to this, firstly programing the 6847 to select an apropreate graphics mode, which is doable with just pokes/asm so no you don't strictly need the floating point rom to do this.

However since in the basic Atom the does not contain hardware outside the 6847 that encodes the colour signals then although you can program it to output colour, because the hardware is not there it will still only output a monochrome signal.

Both the Acorn colour interface and my prototype take the signals that the 6857 outputs and combine them to produce RGB video.

Another consideration is that to use modes other than text mode you will need more than 1K of video ram.

Cheers.

Phill.

User avatar
sirmorris
Posts: 771
Joined: Wed Feb 11, 2009 12:18 pm
Location: oxfordshire uk
Contact:

Re: Atom upgrade pics as promised.

Post by sirmorris » Sun Sep 05, 2010 7:36 pm

=D>

I haven't had the time for soldernating since I returned from holidays so I can't offer any up-thumbs just yet but I'm sure all will be well!

Phill - I think we need to consider a small run of 8k video-ram replacement pcbs. I reckon you could get 6 on a eurocard. Up for it? :D

I'm loving the colour board. Lots. Imagine this - :^o - except it's not the nose that's growing ;) :lol:

Prime
Posts: 2747
Joined: Sun May 31, 2009 11:52 pm
Contact:

Re: Atom upgrade pics as promised.

Post by Prime » Sun Sep 05, 2010 9:07 pm

sirmorris wrote:=D>

I haven't had the time for soldernating since I returned from holidays so I can't offer any up-thumbs just yet but I'm sure all will be well!
Hey no probs :)
I don't expect there to be aby problems, but experience has taught me both as a programmer and as a hardware hacker, it doesn't matter how many times you test it in controled conditions, the users will break it the first time they run it ! :) :) :)
Phill - I think we need to consider a small run of 8k video-ram replacement pcbs. I reckon you could get 6 on a eurocard. Up for it? :D
Well, managed to get 4 onto a eurocard with 2 of the "pre production" prototype colour boards so 6 would probably fit. I have one now fitted to Atom #2 and it seems to work with no probs.
I'm loving the colour board. Lots. Imagine this - :^o - except it's not the nose that's growing ;) :lol:
[butthead]
Put that away Beavis, you're not supposed to have your penis out when you are cooking !
[/butthead]

Well we'll see if it works once I have finished assembling the board, if it does, I'll do a re-design without the carier board for the converter chip, wich is only availabal as a tssop, if I use a surface mount for the LS02 as wall I recon I can get the board down in size a little, it's currently 80mm by 36mm and plugs into PL4

I'll post some piccies once it's assembled.

Cheers.

Phill.

User avatar
ukretrogamer
Posts: 432
Joined: Mon Nov 09, 2009 8:55 pm
Location: England's largest town
Contact:

Re: Atom upgrade pics as promised.

Post by ukretrogamer » Sun Sep 05, 2010 9:14 pm

You can certainly put me down for an Atom colour card as well once you start production.

I just love the hardware hacking which is prevalent on this forum. It really does keep things interesting!

It *never* ceases to amaze me, the modern solutions you guys are finding to add to these old micros.

Absolutely fan-bloody-tastic!

User avatar
ukretrogamer
Posts: 432
Joined: Mon Nov 09, 2009 8:55 pm
Location: England's largest town
Contact:

Re: Atom upgrade pics as promised.

Post by ukretrogamer » Sun Sep 05, 2010 9:22 pm

BeebMaster wrote:What's the official line on the unexpanded Atom being able to do colour, by the way? I think I talked to some of the Atom boffins at Bletchley about this because Atomic Theory & Practice is very misleading in my opinion about being able to get colour without buying a colour board. It appears to suggest that you can type in a load of assembler to do direct graphics plotting and then get colour, without having to have the Floating Point ROM with the COLOUR command. However I think this method only gives you greyscales and not actual techni-colour.
Apple did something similar with the Apple II. IIRC, Steve Wozniak found a way of gaining colour from the existing hardware via software hacking but due to incompatibilities between NTSC & PAL formats, it wasn't available over here. Instead, they sold a PAL Colour Encoder card which had Phono and UHF modulated outputs.

It took me ages to track down a PAL Encoder card for my Europlus. When I did find one, I managed to collect one for a tenner, shortly after a boxed one sold on eBay for hundreds of Euros. I was well chuffed!

User avatar
sirmorris
Posts: 771
Joined: Wed Feb 11, 2009 12:18 pm
Location: oxfordshire uk
Contact:

Re: Atom upgrade pics as promised.

Post by sirmorris » Mon Sep 06, 2010 8:43 am

You cannot get colour out of an atom without a colour card.

The video chip puts greyscale video out, and also the raw ingredients needed to produce colour but the final ingredients of the colour cake (tm) need to be added in order to achieve this.

Phill - would a combined video memory/colour card board be a go-er? The RAM sockets would provide grip and you could connect to the video pins via a flying lead...

C

User avatar
BeebMaster
Posts: 2787
Joined: Sun Aug 02, 2009 4:59 pm
Location: Lost in the BeebVault!
Contact:

Re: Atom upgrade pics as promised.

Post by BeebMaster » Mon Sep 06, 2010 10:37 am

I think I've got the picture now (greyscale only, naturally!) but it still think it's far less than clear in "Atomic Theory & Practice". Do you think we should contact Sophie to issue an erratum !!??
Image

Prime
Posts: 2747
Joined: Sun May 31, 2009 11:52 pm
Contact:

Re: Atom upgrade pics as promised.

Post by Prime » Mon Sep 06, 2010 10:43 am

sirmorris wrote:Phill - would a combined video memory/colour card board be a go-er? The RAM sockets would provide grip and you could connect to the video pins via a flying lead...
That thought did cross my mind, but for the first itteration, just wanted a proof of concept that was independent of the ram, might evenbe possible to design a board that plugged into all the points on the atom board that it needed to, would be an odd shaped board tho....

That is the advantage of having both a lightbox, and an unpopulated Atom mainboard, I can print my board on transparency and then use the lightbox and board to make sure everything lines up correctly.....did that over the weekend for the video ram board, as I already managed to screw that up on my first attempt :(

Cheers.

Phill.

Post Reply