Bruce Abbott

IntyColor and jzintv have 68k versions. IntyBASIC is ppc only, but the source code is included so it could theoretically be re-compiled for 68k.

Looking good...

Well that's embarrassing. The 1.0 ROM should have been on my Website, but I didn't upload it - until now! aqubasic_rom_1.0.zip

You can append binary code to the end of a BASIC tape file and it will be loaded in with the program, but there is a catch - the end of the tape file is marked with 10 zero bytes, so if your code has 10 consecutive zero bytes in it the tape loader will quit at that point. If you can ensure that the binary doesn't have any more than 9 consecutive zero bytes in it then you're fine, otherwise you have to mangle the data and restore it after loading. CLOAD loads BASIC programs into the memory location stored in $384F,50 (14415,6). In a stock Aquarius this will be $3901, but extended BASIC needs more system variable space so it moves the start of BASIC up to a higher memory location. That means any code you embed in the file will also be moved up, so you can't rely on it being at a fixed memory location. The solution is to compile your code for a location that is guaranteed to be beyond the end of the BASIC loader (eg. $4000), then in your loader move the code to its correct location before jumping into it. On a real Aquarius loading from tape is very slow and unreliable, so it might be better to put it in a cartridge ROM.

Does this mean you fixed the problem you were having with wrong colors? If the color is good on a normal monitor it should be similar on the XRGB, unless it has different terminations (should be 75 Ohms to ground on the R G and B lines. If it doesn't have this then you may need to add resistors, and perhaps buffer amps to maintain the correct signal level and impedance).

I am happy to have another beta tester. However grips03 is having some problems with his board (it only works when the PCB is severely flexed, and 2 resistors are bad) so I would prefer to wait until this has been resolved before sending out another one. From now on I will ship via parcel post only (an extra $10) to lessen the risk of damage. I will also make a test circuit to ensure that it works 100% before shipping!

I don't have an Intellivision (and no way of getting one) so I cannot test it. However since I have couple of spare boards and enough parts, I am happy to sell you one at cost on the understanding that there is no guarantee it will work properly in the Inty. Do you have the skills and equipment to install it and work through any problems that might occur? Are you willing to be a 'beta' tester? Cost of PCB with parts installed (no wires or connectors):- PCB $7 GAL22V10 (programmed) $4 24 pin IC socket $1 10 x smd resistors, 2 x caps $3 Total component cost: $15 If it will fit in an envelope (max. thickness 10mm) then postage will be $5, for a total of $20.

Not being satisfied with the composite video output, I bread-boarded a circuit using an AD724 RGB to NTSC/PAL Encoder. The results so far are quite encouraging - no streaking or noise, and of course no pixel distortion because the signal is going through the RGB GAL. The encoder circuit draws about 35mA, about the same as the THS7314 video buffer. For this test I used an external 14.318MHz oscillator, which introduced some shimmer due to not being phase locked to the Aquarius. Next I will try using the Aquarius internal 3.57MHz clock. The AD724 can also output S-video, which should produce an even better picture on TVs which have S-video input. Though the AD724 encoder could be added to my RGB board it might be better as an external add-on, then it could be used with other devices. This could have its own oscillator (perhaps with both NTSC and PAL crystals) or use the Aquarius 3.57MHz clock (NTSC only) fed through the RGB connector. Now that I know how good composite video can be, I will also investigate further to see whether the streaking and noise on the stock Aquarius composite signal can be reduced.

Here is the result. Colors are based on the chart in this post by Snafu-1982. I took the 8 bit RGB values and simply divided them by 32 to get 3 bit values. My camera didn't do a very good job - in reality the colors are more vibrant and closer to the chart. I think it looks pretty good! IVRGB.pld.txt

Looks like it should be able to do it. The AY-3-8915 color encoder in the Intellivision has 5 digital inputs which select 1 of 16 colors plus blanking and sync. This is similar to the Aquarius except that it encodes everything into the 5 bits instead of having a separate sync bit. I will calculate the required RGB levels and try it out on the Aquarius!

A 4.7uF capacitor across the 5V supply removed the faint vertical lines on RGB. Total current draw varied from 30-46mA depending on screen content (3-18mA of this being consumed by the 75 Ohm terminations in the TV). With the video amp installed and terminated (RGB output disconnected) the total current draw was 45-55mA. As expected the composite image is blurry and muddy, with horizontal streaks and vertical lines sometimes visible, but still much better than the original rf signal. Colors are better than the images below suggest, as my camera tends to oversaturate red and blue.

Success! At first the colors were messed up and I couldn't figure out why. All the color mapping equations looked correct, cables were wired correctly - what could be wrong? Then I realized that I had programmed the input signals in the wrong order. No problem - simply reassign the pins in WinCUPL, reprogram the GAL and now it's working perfectly! The GAL draws 26~28mA (varying slightly with pixel density) which is less than I expected. Next step: install and test the composite video and audio circuits. The PCB could do with a few minor changes. Unfortunately the 8 pin socket I choose turned out to be the type 'B' version with 41º pins, and the PCB layout for type 'A' sockets is different. This is not a problem if you use a panel-mount socket. I can see faint vertical lines on some colors, indicating that the +5V supply needs more filtering. So far I have only programmed the GAL with the stock Aquarius color palette. This is using up 6 out of 10 available product terms on one of the Blue outputs, which may limit what other palettes can be installed. Now I have to decide what second palette I want and see if it will fit.

9 outputs produces 512 colors, which is the same as the Atari St. I could use all 10 outputs (4 outputs on green) to get 1024 colors. The circuit should able to work with a variety of machines. CGA doesn't have a pixel clock so it would simply run unclocked like my earlier RGB interface, and CBLK won't be needed if the RGB signals are already low during the sync period.

PCB design sent. Boards expected to arrive in about 3 weeks.