Uzebox & SRAM

Discuss anything not related to the current Uzebox design like successors and other open source gaming hardware
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Roukan
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Re: Uzebox & SRAM

Post by Roukan »

OMG that clock is just insane (in a good way ofc) - never seen anything like that before.

From what both of you have shown/discussed there's plenty of potential out there to meet all the the things on my list (and then some).

I'm very interested to see Uze's $0.02 on this, especially relating back to his earlier retro computer that the Uzebox was born from.


Cheers

Roukan / Jim
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uze6666
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Re: Uzebox & SRAM

Post by uze6666 »

I received my Digikey order yesterday: Two Atmega1284-PU and two 28.6Mhz crystal clock modules (SER1820-ND). Just tested them and same as before...doesn't work. They even won't run at all. :( Oh well, was worth trying.
I'm very interested to see Uze's $0.02 on this, especially relating back to his earlier retro computer that the Uzebox was born from.
I was still thinking about my answer... ;) When I started to work on my retro-computer back then it was based on an ATmega162. This MCU was the only ATMega DIP part with an external bus. It had 32K of SRAM, and FLASH ROM, an 8bit DAC for sound and another mega162 to act as a matrix decoder for my keyboard (looked like a TI-99 keyboard). It has a monochrome output capable of generating 80x25 characters and graphics. All worked fine and it was fun. However, after a while I started to think that a Harvard architecture micro-controller like the Atmegas makes a poor choice for a computer. Because code can only run from flash, loading new programs is cumbersome and flash has a limited numbers of cycles. Plus you can't have cool things like self-modifying code, loading modules of code, etc. Flash is also slow. It takes about 4 seconds to flash 64K, must be painful to wait on larger devices.

So for me a computer based around a real retro CPU like a Motorola 6809 or 68000 (one that has a GCC target) would seem a better fit. Would have a small bios/monitor, lots of SRAM using bank switching, some VGA or composite graphics interface, mono sound, a SD card interface, PS/2 keyboard and perhaps mouse and some expansion port(s). Would all be through hole parts and DIY like the Uzebox. Would be awesome to have a custom plastic enclosure too.

With that said, I though there would not be a lots of folk out there who would seriously use such a computer. One builds it, run a few programs then get bored probably rather quickly. A game console in my mind appeared as having more appeal and "replayability". In the end that's why I focused on the Uzebox instead of the computer. Right now I fail to find motivation to work on a retro computer, but don't let my ramblings deter you of doing one. After all, what counts is learning something and having fun doing it! :)
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Roukan
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Re: Uzebox & SRAM

Post by Roukan »

uze6666 wrote:I received my Digikey order yesterday: Two Atmega1284-PU and two 28.6Mhz crystal clock modules (SER1820-ND). Just tested them and same as before...doesn't work. They even won't run at all. :( Oh well, was worth trying.
I'm very interested to see Uze's $0.02 on this, especially relating back to his earlier retro computer that the Uzebox was born from.
I was still thinking about my answer... ;) When I started to work on my retro-computer back then it was based on an ATmega162. This MCU was the only ATMega DIP part with an external bus. It had 32K of SRAM, and FLASH ROM, an 8bit DAC for sound and another mega162 to act as a matrix decoder for my keyboard (looked like a TI-99 keyboard). It has a monochrome output capable of generating 80x25 characters and graphics. All worked fine and it was fun. However, after a while I started to think that a Harvard architecture micro-controller like the Atmegas makes a poor choice for a computer. Because code can only run from flash, loading new programs is cumbersome and flash has a limited numbers of cycles. Plus you can't have cool things like self-modifying code, loading modules of code, etc. Flash is also slow. It takes about 4 seconds to flash 64K, must be painful to wait on larger devices.

So for me a computer based around a real retro CPU like a Motorola 6809 or 68000 (one that has a GCC target) would seem a better fit. Would have a small bios/monitor, lots of SRAM using bank switching, some VGA or composite graphics interface, mono sound, a SD card interface, PS/2 keyboard and perhaps mouse and some expansion port(s). Would all be through hole parts and DIY like the Uzebox. Would be awesome to have a custom plastic enclosure too.

With that said, I though there would not be a lots of folk out there who would seriously use such a computer. One builds it, run a few programs then get bored probably rather quickly. A game console in my mind appeared as having more appeal and "replayability". In the end that's why I focused on the Uzebox instead of the computer. Right now I fail to find motivation to work on a retro computer, but don't let my ramblings deter you of doing one. After all, what counts is learning something and having fun doing it! :)
Hi Uze

Thanks for your feedback.

I have to agree about the console having a greater appeal to the majority of the people that dabble in these areas :( .

And after doing some research on the Atmel MCU's see that only being able to execute native code from flash is the main problem, leaving only the option of some kind of Virtual Machine or 8 bit CPU emulator running from flash and working with code stored in SRAM/RAM - which would have quite an impact on performance.

Like you say the "a real retro CPU like a Motorola 6809 or 68000" is the best way to go.

From my point of view this is more out of reach than than the AVR based solution as it doesn't exist, but if for example any of the current console projects like the Uzebox / AtomicZombie's / Masterburg's had support for all of Keyboard/Mouse/SD card along with their Video/Audio/Gamepad features it might of been possible to attempt to code something up (after learning AVR assembly language).

Alas they don't so that's a none starter.

I simply don't have any electronic/hardware skills at all and I'm far to old to start learning now, hence the earlier quote about the "Lotto Win" to wave some cold hard cash someone's way - lol.

On the plus I'm having so much fun working on my Uzebox projects/ bit and pieces, this is where it's at for me and stems back to the start of the 80's when I used love coding in Basic / z80 & 6502 assembly language.


Cheers


Roukan / Jim
AtomicZombie
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Re: Uzebox & SRAM

Post by AtomicZombie »

So with the clock feeding XTAL1 with a setting of EXT clock with 0ms, you get nothing at all?
That's really odd. I still have my 32MHz 1284 project on an old breadboard, doing VGA.
I wonder why it fails?

Brad
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uze6666
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Re: Uzebox & SRAM

Post by uze6666 »

AtomicZombie wrote:So with the clock feeding XTAL1 with a setting of EXT clock with 0ms, you get nothing at all?
That's really odd. I still have my 32MHz 1284 project on an old breadboard, doing VGA.
I wonder why it fails?

Brad
Yep. I can communicate with the chips via ISP, but no code will run. Perhaps you got lucky to get a working chip? I have only one out of ten 1284 that works, that's how I know the setup works.
AtomicZombie
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Re: Uzebox & SRAM

Post by AtomicZombie »

Not sure what else to try. Considering my messy breadboard, I would have figured you would have even better results than I did. I guess I would have to mess around with your hardware to see what it is I am doing differently. There was some quirk though, and I just can't remember what it was. Something with Studio5 and STK500, both of which I no longer use. I remember using only 5.0v, using the last clock setting with 0ms delay, and having to tell Studio to erase before programming. Once I had the fuse settings, all 1284's I had clocked fine up to 32MHz.

My systems did not use EEPROM or built in peripherals though, just all the SRAM / progmem and IO pins.

Too bad you are a day's drive away, I like a challenge!

Brad
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uze6666
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Re: Uzebox & SRAM

Post by uze6666 »

Yeah I did all those things and so many more. Tried almost all clock modes (even the slow ones). No luck. :(
AtomicZombie
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Re: Uzebox & SRAM

Post by AtomicZombie »

Bugger! I guess you are right about just having a "lucky" batch of 1284s then. I hope the XMega isn't like that. So far they have all tested fine at 2x speed.
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mast3rbug
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Re: Uzebox & SRAM

Post by mast3rbug »

Hi Brad.

Any new development on your console?

from my side, I finished the video drivers, I'm now writing my first game. Turrican II with original music. I have found all the sprites on internet. Really cool.

Mast3rbug
AtomicZombie
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Re: Uzebox & SRAM

Post by AtomicZombie »

mast3rbug wrote:Hi Brad.
Any new development on your console?
from my side, I finished the video drivers, I'm now writing my first game. Turrican II with original music. I have found all the sprites on internet. Really cool.
Mast3rbug
Turrican was a great Amiga classic! A good choice for a conversion indeed.

Yes, I have completed all 4 of my console / video game systems now. But I only do this stuff on weekends, so it will take a month or 2 more to get my website up with all the source code and schematics.
The ones I intend to document first are...

1) Ulta simple BW/Color pong system on ATTiny 85. Video on the fly, all assembly.
2) 426x300 XMega VGA system using external 512k SRAM. Main loop is C.
3) Ultra fast / powerful FPGA based system using XMega and Spartan6. XMega programmed in C.

And my favorite, the one I am getting boards made for...

4) Vixen384 - Single chip XMega NTSC color gamesystem with loads of power / super easy coding with main loop programmed in C.

Will be on the hunt to profile as many other Atmel based audio / video projects as I can as well including your systems and of course the one that made this great community happen... UZEBox.
I will probably disappear for a few weeks (busy with real work), but will come back and let you know when I have something to show on my site.

Good luck on your game conversion... keep bangin' those bits!

Brad
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