Announcing... the AtmoStrat !

This is the right place to discuss on how to implement hardware vsync, adding a VIA or AY chipset, puting multiple roms, or how to design a new flash expansion card.
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Euphoric
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Announcing... the AtmoStrat !

Post by Euphoric » Wed Sep 28, 2016 7:52 pm

Hi everybody, George Dramcheff has given me the honor to announce his magnificent baby : the AtmoStrat !

A beautiful red motherboard that is much more than an Oric clone...
Here are a few quick specs :
- 96 KB of ROM giving access to 4 configurations thanks to a rear switch : Oric Atmos, Pravetz 8D, HyperBasic, TeleAss
- WD65C816S cpu with 256 KB of DRAM
- composite and S-video outputs in addition of the usual RGB output
- 2 software-selectable video pages and vertical synchronization capability

and as some pictures are always better than words, please have a look at :
http://oric.club/atmostrat

I feel it like the best Oric of all times, but make your mind yourself : if you want to see it in action and are near Toulouse for the upcoming weekend, George has sent me one AtmoStrat so I will be demonstrating it on Saturday afternoon at the Vieumikro annual meeting ( http://silicium.org/site/ ).

Greetings to all !

Fabrice

Side notes:
- the WD65C816S processor is a 8/16-bits cpu, it boots in 6502 emulation mode for a near 100% compatibility with Oric Atmos, and can be switched by software to its native mode in order to benefit from 16-bit registers. On the AtmoStrat, it is clocked at 1 MHz only, in order to keep maximum compatibility with the Orics,
- the 256 KB of DRAM are refreshed by the ULA as usual, and can be accessed both from 6502 emulation mode or native mode. As usual, a fourth of it is only accessible when an external disk controller is attached,
- despite lacking a serial communication chip (ACIA) and the Telestrat specific ULAs, the HyperBasic and TeleAss modes are rendered possible by a software modification of Telemon, and the PB5 bank switching trick. TeleAss might be replaced by TeleForth in the future (and I'm working on a 16-bit OricScheme to provide even more options for native development...)
Last edited by Euphoric on Thu Sep 29, 2016 9:06 am, edited 1 time in total.

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Chema
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Re: Announcing... the AtmoStrat !

Post by Chema » Wed Sep 28, 2016 8:10 pm

Okay I am not very fond of this kind of "super-vitaminised" replicas of old computers, however I must admit this one is beautiful and really interesting.

Congratulations George! Incredible work!

:shock:

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Re: Announcing... the AtmoStrat !

Post by Dbug » Wed Sep 28, 2016 8:39 pm

Is it an impression... or does it actually fit inside a standard Atmos case?

In any case, it looks very professional :)

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Re: Announcing... the AtmoStrat !

Post by jede » Wed Sep 28, 2016 9:37 pm

Really good news ! :)

How to build it ? will someone release gerber file ? or it will be build by someone ?

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Re: Announcing... the AtmoStrat !

Post by coco.oric » Thu Sep 29, 2016 3:44 am

Very good.

I'm sure that George will sell it soon and that amateurs will be able to try it. however, i'd prefer seeing one with an rs-232 and a fdd controller built-in ; it'll be better to link it to a pc for example to transfer files to disk and to use a disk drive or a gotek clone.
Always with a 65C816, the real oric super-vitaminised is the Super-Oric (on SNES)
coco.oric as DidierV, CEO Member
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Re: Announcing... the AtmoStrat !

Post by Dbug » Thu Sep 29, 2016 7:48 am

Fabrice: Do we have details about the video sync capability? Is it manual, or is it automated?
(On the picture it looks like a two pin bridge with a connector on it)

Also, is that the final design of the board?

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Re: Announcing... the AtmoStrat !

Post by iss » Thu Sep 29, 2016 9:55 am

First congrats to George (jorodr) for the incredible AtmoStrat.
I have this jewel since April (but I had to keep it secret ;)) - it's really cool!
I tested it with Microdisk, Cumana, 8D-FDC and Cumulus and ... it worked fine!

The PCB fits perfect in the standard Oric case - even more, it's designed to be so.
The Video sync is exactly the famous VSync hack. The wiring is made on the PCB and with the jumper
(seen on the picture) you can turn it on/off.

But the most important thing are the two real video pages. They can be switched with one simple POKE :).

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Re: Announcing... the AtmoStrat !

Post by Dbug » Thu Sep 29, 2016 1:13 pm

iss wrote:The Video sync is exactly the famous VSync hack. The wiring is made on the PCB and with the jumper
(seen on the picture) you can turn it on/off.
It's what I thought.
How difficult would it be to make the switch done automatically when not using the TAPE for loading or saving?

When we load or save stuff, we enable the RELAY to start the tape drive, so it should be relatively uncomplicated to automate the VSYNC by having the TAPE-IN to VSYNC connection done only when the relay is not ON.

What do you think?

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Re: Announcing... the AtmoStrat !

Post by iss » Thu Sep 29, 2016 2:35 pm

Okay, let's reveal some AtmoStrat secrets :);
In AtmoStrat the normally unused VIA pin PB5 is used to switch ROM banks.
And the PB6 which drives the tape relay is used to select which video page to be displayed :).
Of course all required modifications in all ROMs are done properly by Fabrice (Euphoric).

So, unfortunately the idea to use the PB6 to switch between VSync and Tape-in will not work
with the current version of AtmoStrat.

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Re: Announcing... the AtmoStrat !

Post by Dbug » Thu Sep 29, 2016 4:44 pm

iss wrote:And the PB6 which drives the tape relay is used to select which video page to be displayed :).
Does that switch both the video memory AND the character sets?
iss wrote:So, unfortunately the idea to use the PB6 to switch between VSync and Tape-in will not work
with the current version of AtmoStrat.
Ok :'(

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Re: Announcing... the AtmoStrat !

Post by Euphoric » Fri Sep 30, 2016 11:37 am

Dbug wrote:
iss wrote:And the PB6 which drives the tape relay is used to select which video page to be displayed :).
Does that switch both the video memory AND the character sets?
That's true...when PB6 is 0 all the ULA's video memory accesses are in $00xxxx (including those character sets memory cycles), and when PB6 is 1 all the ULA's video memory accesses are in $03xxxx.

About PB5, George has cleverly spotted that switching roms with PB5 can be a problem with all those Oric software that assumed that PB5 is a no-connect on the Oric-1/Atmos, so PB5 does not switch roms in Atmos mode : PB5 is only used to switch roms in Telestrat mode, ie. switching between the modified Telemon bank, and the unmodified language rom (currently HyperBasic or TeleAss)...

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Re: Announcing... the AtmoStrat !

Post by Dbug » Fri Sep 30, 2016 7:39 pm

Since 03xxxx is not in the 64k addressing range, what happens if you play with PB6 in 6502 mode?

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Re: Announcing... the AtmoStrat !

Post by iss » Sat Oct 01, 2016 10:52 am

Dbug wrote:Since 03xxxx is not in the 64k addressing range, what happens if you play with PB6 in 6502 mode?
This is the tricky part - playing with PB6 only affects which memory content will be displayed on the screen i.e.
when PB6=1 it forces the ULA during the DRAM refresh time (when PHI2 is low) to use memory from $3xxxx instead from $0xxxx.
The CPU is unaffected - simply in 6502 you can access only the first 64k and in 65816 mode you have the whole 256k available.
To display video page $3xxxx use: POKE #300,PEEK(#300) OR #40
to display default page $0xxxx use: POKE #300,PEEK(#300) AND #BF

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Re: Announcing... the AtmoStrat !

Post by Dbug » Sat Oct 01, 2016 1:00 pm

iss wrote:To display video page $3xxxx use: POKE #300,PEEK(#300) OR #40
to display default page $0xxxx use: POKE #300,PEEK(#300) AND #BF
What happens if you change the value while the picture is being drawn, does it immediately change to the other video data?
How does the ULA behave in regard to memory access and CPU accesses: Does it cache anything, can we reach a situation where in TEXT mode the screen value would be read from one location and the character definition from the other location?

I'm trying to see what kind of funny things could be done with that system :D

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Re: Announcing... the AtmoStrat !

Post by iss » Sat Oct 01, 2016 1:42 pm

Yes, changing PB6 results immediately change of video data - I don't think that ULA caches more data than 1 byte.
Else I can't answer if it's possible to use char definitions and text content from different 64k blocks.
But the fact to have 2 completely independent text/hires pages and 2 full sets char definitions (standard+alt) is good base to start with fun experiments :).

Edit: Because ULA access RAM twice in every single PHI2 pulse, it's not possible to have text/char from different 64k blocks, but probably it's possible if we have on text screen ABCDEF, to display A,C,E from one block and B,D,F from the other... or in groups of 2-3 chars, something like that - depending on how fast we can switch PB6.

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