F18A programming, info, and resources

[digress]

I found it. It's fixed.

 

Because the coleco graphics were in bitmapped mode it was duplicating the tiles still and overwriting the second & 3rd colour planes. Now I've got the 8 colour 3bit tiles I was expecting.

 

if interested i posted an updated video with the 3bit tiles working here. I haven't reoloured them much to take advantage yet but a few have been.

 

Thanks for the suggestions & help.

 

http://atariage.com/forums/topic/257913-f18a-enhanced-sprites-on-colecovision/

[matthew180]

I'm glad you got it sorted out. Usually when I'm having a problem like that I will make smaller programs to test each part of the code in isolation. Or, putting the code into an infinite loop at a certain point, like just after VDP initialization, writing the name table, pattern table, etc. Basically just to make sure that what you expected to happen actually did happen.

[Omega-TI]

I've never really seen an "EXTREME CLOSE UP" of the F18A before, so I thought I'd take one and share it with everyone. Attaching it as a downloadable file will keep it in it's original 2116 X 1897 format (so you can see all the detail).

[ralphb]

Maybe I'm wrong, maybe this has been discussed before, but: There's something odd about the timing on a F18A system.

 

Take a look at this screenshot of Parsec running on a European TI 99 with a F18A, version 1.6 (I think):

 

 

You may have noticed that all alien craft are flying lower than on a regular TI. Consequently, if you move your ship up, you can let the game sit alone without your ship ever crashing, and the aliens achieving insane speeds. On a regular TI, the ship crashes rather soon.

 

I guess that Parsec is using auto-motion, so slow alterations in speed (VDP timer? GROM clock?) would cause this. Are there other explanations for this?

 

(The image looks funny as I photographed my 4K monitor where the TI/F18A is running as picture-in-picture -- quite a convenient setup for development.)

 

[Asmusr]

Are you sure it's not just the difference between 50 and 60 Hz you see? I tried a few runs of Parsec in Classic99 at both 50 and 60 Hz and even though there is a noticeable difference in speed it often lets me park safely at the the top of the screen at any refresh rates.

[ralphb]

Fair enough, but both are 50 Hz machines.

 

Here's a short video showing Parsec on the F18A:

 

parsec.mp4

[Asmusr]

Fair enough, but both are 50 Hz machines.

 

Here's a short video showing Parsec on the F18A:

 

parsec.mp4

 

An EU console with an F18A essentially turns into a 60 Hz machine.

[ralphb]

An EU console with an F18A essentially turns into a 60 Hz machine.

 

You're right. I just checked Parsec on a US system, and the yellow alien does crash into the scenery! They wouldn't on an EU system.

 

So there is some difference in game play, in some sense. I wondered how the programmers compensated for different Hertz, and now I know they didn't.

 

But isn't there a DIP switch on the F18A for selecting the frequency? I cannot find the original leaflet that came with the F18A anywhere online.

[Asmusr]

But isn't there a DIP switch on the F18A for selecting the frequency? I cannot find the original leaflet that came with the F18A anywhere online.

 

Nope, it generates a standard 640x480 VGA signal at 60 Hz.

[ralphb]

Nope, it generates a standard 640x480 VGA signal at 60 Hz.

 

OK, thanks for the clarification.

 

@Matthew: Could you publish online that one page manual that came with the F18A? I cannot find mine anymore, and it seems to be the only source for the DIP switch configuration.

[+mizapf]

The Parsec flight level effect is also reproducible with MAME at 60 Hz. I thought I was observing an emulation issue, as the lowest gliders touch the landscape or buildings, but obviously this was indeed the case.

 

While we had the Parsec competition, I noticed that in the 60 Hz version, all three lifts make sense, while in the 50 Hz version, I had no use for lift 2.

[+jedimatt42]

OK, thanks for the clarification.

 

@Matthew: Could you publish online that one page manual that came with the F18A? I cannot find mine anymore, and it seems to be the only source for the DIP switch configuration.

http://codehackcreate.com/archives/365

Matthew's page there documents USR3 and USR4.

I am pretty sure USR1 was for the sprite limit, and USR2 the scan line generator.

 

But I agree, having the official doc online would be very handy.

 

-M@

[Bmack36]

Here you go.

[ralphb]

Thanks, Bmack36!

[matthew180]

Apologizes for the tardy reply.

 

Re: why no 50Hz? To output 50Hz means I would have to decouple the VDP interrupt from the actual video signal, and that would be bad. Everything relies on the interrupt happening at the actual refresh, and there is no 50Hz VGA/VESA mode:

 

http://www.tinyvga.com/vga-timing

 

As for the jumpers, yes my website is lacking (it is on the todo list). Thank you Bmack36 for providing the info. That PDF is also available on the first post of this thread for download.

 

There are four "User Jumpers" on the F18A:

USR1: Selects the power-on default maximum number of sprites on a line. Can be overridden via software;
On = 32 sprites can be displayed on a single line
Off = 4 sprites maximum can be displayed on a single line

USR2: Select simulated CRT scanlines. Virtual Scanlines can be turned on via software if the jumper is on:
On = no simulated scanlines
Off = enables simulated scanlines

USR3: Pin-37 GROMCLK / CPUCLK select:
On = GROMCLK output on pin-37 (9918A/28/29)
Off = CPUCLK output on pin-37 (9128/29)

USR4: Pin-38 CPUCLK enable:
On = disabled (Hi-Z)
Off = enabled

 

The default for the F18A is all jumpers on, which basically sets up a 9928. This works in the 99/4A because the CPUCLK output is not used in the 99/4A (so it is not missed). Some systems (Tomy Tutor, NTSC SpectraVideo SV-328, etc.) actually use the CPUCLK output as the main system clock and need USR2 to be off. USR2 exists because a friend graciously allowed me to modify his SV-328 to test the F18A back in 2012 and it did not work. Since the 99/4A did not use the CPUCLK I originally did not produce that output or connect anything to pin-38. A board revision later and I had a full complement of options for the pin differences among all of TI's 9918A derived VDPs.

  VDP       USR3 USR4
9928/29      on   on    pin-37 GROMCLK
                        pin-38 Hi-Z (disabled)

9918A/9118   on   off   pin-37 GROMCLK
                        pin-38 CPUCLK

9128/29      off  on    pin-37 CPUCLK
                        pin-38 Hi-Z (disabled)

not used     off  off   pin-37 CPUCLK
                        pin-38 CPUCLK

       _________
RAS  =|1   U  40|= XTAL1   9918A    9928A/29A 9118    9128/29 F18A
CAS  =|2      39|= XTAL2   ======== ========= ======= ======= ====
AD7  =|3      38|= ....... CPUCLK   R-Y       CPUCLK  R-Y     HI-Z / CPUCLK
AD6  =|4      37|= ....... GROMCLK  GROMCLK   NC      CPUCLK  GROMCLK / CPUCLK
AD5  =|5      36|= ....... COMVID   Y         COMVID  Y       NC
AD4  =|6      35|= ....... EXTVDP   B-Y       EXTVDP  B-Y     NC
 
Basically:
            USR3 USR4
TI-99/4A     on   on    -- The 99/4A does not use the CPUCLK, but this is NOT the default of the 9918A
9928/29      on   on    -- CPUCLK on pin38 disabled so it does not cram 3.5MHz into the R-Y circuit
9918A/9118   on  off    -- CPUCLK output, GROMCLK output (pin37 is not connected on the 9118)
9128/29     off   on    -- CPUCLK on pin37 enabled, CPUCLK output on pin38 disabled
not used    off  off    -- CPUCLK output on both pin37 and pin38

[+Ksarul]

I love the F18As I have in my various systems--but I actually need one or two more of them. . .so I hope they will be available again soon.

[matthew180]

Working on it, but the Chinese New Year might delay things a bit.

[Bmack36]

How many do you need and where are you located? I have a couple extra I could sell.

[+Ksarul]

I understand that one, Matthew--I'm waiting on production to commence on a board order of my own right now, and holding off on initiating the order for another until later this month.

 

Thanks for the offer Bmack36, but I actually prefer ordering from the guys who produce new hardware/software as a way to directly support their efforts (unless the need is an emergency need that they can't meet--and this isn't one of those).

[Bmack36]

No problem, just trying to help out.

[Omega-TI]

Could this be done on a TI with the F18A...

[matthew180]

Maybe. To get that kind of color overlap you would need to use the BML (bitmap layer) which reduces your usable resolution to 128x96. Other than that, a fast circle drawing routine running on the GPU, and using the DMA to clear the screen between frames is about all your need.

[Omega-TI]

I've been thinking... How nice it would be to have the update program for the F18A in cartridge format.

 

If I'm not mistaken, it's currently too big for the FR99, but with tweaking it could be programmed into a 49F040 right?

 

I'd be happy to put a program like that on cartridge and bring it to Fest West if anyone needs to update their F18A.

 

When the FinalGROM99 finally comes out that could make it super easy for people without disk systems up update.

[Tursi]

But you can run it from a CF card... is that so much less convenient to take to a convention?

[Omega-TI]

I was also thinking about people who will not be coming to Fest West that do not have a Nano-PEB, CF7 or full-fledged expansion box