Let's design a new video mod

[supercat]

The issue I think would be timing. It needs to read and write from ADC/DAC ports at the same time and (particularly with writing) do it at precise intervals, then in the middle of the screen it somehow needs to send blanking and HSYNC pulses to the output without missing a beat. I'd be surprised if it could be pulled off effectively with a single MCU.

 

The clock would have to be derived from the TIA's clock, so that a known number of cycles would happen every TIA clock. With that taken care of, if one were running at a rate of 16x the chroma clock, one could simply have a loop which took about 228*16 cycles, taking an extra cycle if it saw a phi2 in the wrong place, or an extra 48 cycles if, for six or more scan lines in a row, it didn't see a sync pulse in the right place. The ARM would only have to worry about outgoing sync pulses during those parts of the line when it wasn't having to worry about incoming picture data, and would only have to worry about incoming sync pulses during those parts of the line it wasn't having to worry about any picture data.

 

With an ARM clock of 16*chroma, it might almost be possible to have the ARM do everything, including watching the 6502. It would be tricky, since one would have to worry about watching for TIA writes every 48 clocks, but since one only has to watch for TIA writes once every three pixels it might be possible to do it if one spreads out the work of handling TIA writes. My guess would be that the timing wouldn't be too terrible if one were willing to restrict TIA COLUxx to once every three cycles (a restriction which would work with all "normal" code).

 

The inner "loop" would probably be a macro that handled three chroma clocks (48 cycles):

; R13 -- I/O port base
; R12 -- Pointer for video data to be output
; R11 -- Pointer for video data coming from TIA
; R10 -- Active color base

; R4 -- Color data being computed for output
; r3 -- Temp data fetched from TIA
; r0-r2 -- Data fetched from buffer
; 
; Assume r0-2 are loaded with next three words to be output, and r5 is r0>>16
; Cycle 0
 strh  r0,[r13,#OUT]
 ldr   r3,[r13,#IN]   ; Top two non-blank bits must be luma bits, and next lower bit must be blank
 ldrh  r4,[r10,r3,lsr #whatever]
; Cycle 8
 strh  r5,[r13,#OUT]
 lsr   r0,r1,#16
 sub   r3,#Whatever ; Subtract base address of COLUxx
 lsls  r3,#Whatever ; See if everything is valid for a COLUxx write (will be zero if so)
 bleq  handle_write
 nop  ; Show there is enough time to deal with things in branch case
 nop
; Cycle 16
 strh  r1,[r13,#OUT]
 ldr   r3,[r13,#IN]
 ldrh  r5,[r10,r3,lsr #whatever]
; Cycle 24
 strh  r0,[r13,#OUT]  ; Value that was in r1, shifted right 16
 add   r4,r4,r5,asl #16
 str   r4,[r11,#4]!
 lsr   r0,r2,lsr #16
 ; 2 spare cycles
; Cycle 32
 strh  r2,[r13,#OUT]
 ldmia r12,{r0,r1,r2}
; Cycle 40
 strh  r5,[r13,#OUT]
 lsr   r5,r0,#16
 ; 5 spare cycles

Including five cycles to handle a test for whether a TIA write cycle is occurring, the code ends up fitting with 7 cycles to spare when using a 16x clock (assuming a fully-unrolled loop for the parts of the line which require simultaneous latching and display of data). A COLUxx would knock things a little "behind", but on the next 6507 cycle one could skip the check for a COLUxx store, and thus get caught up.

 

Perhaps it would be possible to make things work. It would certainly be very close.

[mtshark7]

Batari: When do you plan for the final product to be completed? Also do you plan to do a AV & pause combo circuit?

[SlowCoder]

Also interested. The LHE mod is way too expensive for what it is. Excellent mod, perhaps, but not worth >$100. And finding the parts is very difficult, at least for me, a circuitry noob.

[Uzumaki]

^^ bump ^^

 

any update? Been waiting with bated breath for a decent AV mod that is friendly to LCD TVs, not like the wire and resistor mod used in old FAQs and those used for Ben's VCSp, and doesn't cost an arm and a leg to buy.

[mtshark7]

This is where I bought my LHE video mod and it works PERFECTLY!

 

eBay Seller: electronicsentimentalities

 

A lil annoying that you have to buy the wires and the sockets separately tho

[Rex Dart]

This is where I bought my LHE video mod and it works PERFECTLY!

 

eBay Seller: electronicsentimentalities

 

A lil annoying that you have to buy the wires and the sockets separately tho

 

I'm sorry... but that seller's "Plum smoker wood" sounds downright vulgar.

[LittleJoe]

I'm sorry... but that seller's "Plum smoker wood" sounds downright vulgar.

 

Hey, I actually sold one of those! Good review too.

 

 

Anyhow, I've switched over to selling BAtari's excellent open source mod for the 2600 with his OK. I've got the assembled boards up now, complete kits and bare boards coming soon.

 

 

eBay Auction -- Item Number: 290587575364

[axh174]

Littlejoe, that's great news!

 

Are those boards using the FMS6400/FMS6406 or the ML6428?

 

What do you figure is the ETA on complete kits?

Edited August 15, 2011 by axh174

[LittleJoe]

There's a jumper to supply +5 to pin 2 if needed so the 6406 and 6400 will work. I've not used it myself but I don't see why the ML6428 wouldn't work.

 

I should have the complete kits up on 8/22. Just need to touch up the instructions.

 

Littlejoe, that's great news!

 

Are those boards using the FMS6400/FMS6406 or the ML6428?

 

What do you figure is the ETA on complete kits?

[mimo]

I'm sorry... but that seller's "Plum smoker wood" sounds downright vulgar.

 

Hey, I actually sold one of those! Good review too.

 

 

Anyhow, I've switched over to selling BAtari's excellent open source mod for the 2600 with his OK. I've got the assembled boards up now, complete kits and bare boards coming soon.

 

 

eBay Auction -- Item Number: 290587575364

Any idea if this will work with a Sears Video Arcade II?, will you ship to the UK?, is there a discount for buying a 2600+7800 mod?

[toymailman]

I just ordered mine from your website. This will be part of a Christmas present for my brother and his family. S-Video/Stereo modded 2600 with a fully loaded Harmony. Fun!

 

I will order one for myself later as well. Then I will have the CyberTech, Longhorn Engineer, and bBatari versions. Each will be easily identified in my collection because:

CyberTech = 4-switch Vader console

Longhorn = 4-switch Woody console

bBatari = 4-switch Sears console

 

I hope Nathan gets some time eventually to update his website will full reviews and comparisons of the various mods now. Also, still hoping the CyberTech Pro will come some time.

[+Nathan Strum]

I hope Nathan gets some time eventually to update his website will full reviews and comparisons of the various mods now. Also, still hoping the CyberTech Pro will come some time.

It's on my "to-do" list. I don't know when I'll be able to get to it though. There are a few other projects that need to get taken care of first.

[keilbaca]

I'm sorry... but that seller's "Plum smoker wood" sounds downright vulgar.

 

Hey, I actually sold one of those! Good review too.

 

 

Anyhow, I've switched over to selling BAtari's excellent open source mod for the 2600 with his OK. I've got the assembled boards up now, complete kits and bare boards coming soon.

 

 

eBay Auction -- Item Number: 290587575364

Any idea if this will work with a Sears Video Arcade II?, will you ship to the UK?, is there a discount for buying a 2600+7800 mod?

 

I installed one on an NTSC Sears Video Arcade II without any issues at all. I also installed a pause switch without any issues.

[Ethaniel]

What about PAL consoles?

[alex_79]

What about PAL consoles?

See post 86.

Edited October 24, 2011 by alex_79

[Ethaniel]

What about PAL consoles?

See post 86.

Well i already read that but 1rst it says "maybe" and 2nd the ebay item is listed as NTSC only, so i'd like some confirmation before i get one

[axh174]

I have a question regarding the installation of the BAtari mod. What is the significance of lifting pins 6, 9, 12, and 13? (I believe these correspond to the Blanking signal, Chroma out, and Audio R/L out) What happens if you don't lift the pins, but still solder to these points? Is it an interefernce issue? A concern over voltage division in the resistor network? If so, why are these pins lifted, but the Luminance pins are not?

 

Thanks.

[keilbaca]

I have a question regarding the installation of the BAtari mod. What is the significance of lifting pins 6, 9, 12, and 13? (I believe these correspond to the Blanking signal, Chroma out, and Audio R/L out) What happens if you don't lift the pins, but still solder to these points? Is it an interefernce issue? A concern over voltage division in the resistor network? If so, why are these pins lifted, but the Luminance pins are not?

 

Thanks.

 

On the Video Arcade II, I didn't lift up the pins, but I cut the traces right past the pins. Pin 6 did not have anything under it to go to trace wise, so I left it alone. My video quality is fantastic

[axh174]

On the Video Arcade II, I didn't lift up the pins, but I cut the traces right past the pins. Pin 6 did not have anything under it to go to trace wise, so I left it alone. My video quality is fantastic

 

Interesting note there on pin 6. In the schematics for the 4-switch located in the archives, Pin 6 on the TIA is omitted. I've got a Rev 14, 4-switch and it has Pin 6 tied to Pin 9 via an 820 Ohm resister, which is more like the 6-switch schematic. Dunno if it was purposefully omitted or just missed?

 

Either way, I'm curious as to why the pins need to be lifted / traces need to be cut. I would assume it is due to (potential) interference from the rest of the circuit, but not sure. Looking to satisfy my curiosity. Anyone have any insight?

[+thegoldenband]

This may seem like a strange question, but are there any top-quality video mods that don't involve adding S-Video? It seems like S-Video adds quite a bit of complexity to both the circuit and the installation process, not to mention cost, and I can't help but feel it'd be silly to go to that effort if I don't have any gear that supports it.

 

OTOH it's true that I'm also thinking about ways to give consoles to my siblings who have (I assume) moved on to LCD and plasma TVs that don't support RF connection, and those might get better results with S-Video than composite (if those TVs have S-Video connectors). But it'd still be nice to have an option I could easily install with very-minimal-to-nil soldering experience.

[Uzumaki]

This may seem like a strange question, but are there any top-quality video mods that don't involve adding S-Video? It seems like S-Video adds quite a bit of complexity to both the circuit and the installation process, not to mention cost, and I can't help but feel it'd be silly to go to that effort if I don't have any gear that supports it.

 

TIA outputs chrome and luma natively, which is basically S-Video. The mod actually gets more complex when it offers composite without degrading signal too much, like the earlier mods that simply ties the output together.

 

OTOH it's true that I'm also thinking about ways to give consoles to my siblings who have (I assume) moved on to LCD and plasma TVs that don't support RF connection, and those might get better results with S-Video than composite (if those TVs have S-Video connectors). But it'd still be nice to have an option I could easily install with very-minimal-to-nil soldering experience.

 

A pre-assembled board is about as easy as you can get, just skip adding in S-Video port. The original video mod seen in old 2600 FAQs is more complex than the board.

[axh174]

Bought an unassembled BAtari video mod kit from LittleJoe's ebay store and had a blast assembling it an installing it. Picture looks great through both the Svideo and the Composite on my analog TV, still have to check it out on my LCD HD.

 

I'm having some issues adjusting the brightness and the contrast, though. For example, I was playing Cosmic Ark and the background was far too bright (gray space field instead of black). I Turned the brightness pot all the way up and noticed the entire field "dropped a shade" to much darker overall colors when I hit the pot's limit. Dialing back the pot slightly gave me a black star field while the Ark and Beasties planetscape were rich colors. Looked absolutely amazing! However, if I turned the console off and back on the colors are far to bright again and washed out even though I hadn't touched the pot. Adjusting it can get the rich colors again, but they always end up washed out when I turn the console off and back on.

 

Any idea what could be causing this? bad pot?

Edited November 11, 2011 by axh174

[toymailman]

I got mine a few days ago and tested it out. It looks and works great. The workmanship is top notch; he even cleaned the console.

 

I did use the VideoSoft Color Bar Generator to adjust the phase and it dialed in the colors really well. I have not checked out Cosmic Ark.

[ApolloBoy]

I got the Batari board for Xmas and I installed it earlier today in my Heavy Sixer. The install was absolutely painless and the picture quality is excellent!

[thorr]

I had my mod done by LittleJoe. Very professional work! He cleaned up the dust on my Atari as well. The RF cable has been removed (as I expected since it wouldn't work anymore). The video and sound quality are excellent and it is neat hearing Atari games in Stereo. Stereo takes a little getting used to, but it adds dimension to the games. Some sounds come out the left channel and others come out the right channel. Once in awhile, they are coming out both channels and the sound is centered. I would say I prefer stereo over mono, but it is strange at first. I haven't tried adjusting the pots yet because it already looks pretty good to me. Thanks for a job well done LittleJoe! This removes my need to use my Flashback 2 and my desire to mod it. I have a real Atari with great video quality now, and combined with the Harmony, I can play whatever I want and it just works. I also bought Star Raiders on ebay so I will have the controller. I used to have it at my dad's house, but he got rid of it without asking me first. Can't wait to play it again!

Edited January 21, 2012 by thorr