Paku Paku -- 1.6 released 9 November 2011

[jmetal88]

I was just about to post a link to that PDF for you.

Looks like $3DA port 03 is used to set the portion of the attribute byte that controls blinking.

[deathshadow60]

Ok, the following contains two .exe's.

http://www.cutcodedown.com/retroGames/a ... KU1_32.RAR

The first, paku.exe uses the text-mode 160x100 trick and uses that $3DA port to set the blink off (in theory). This would be the preferred version IF it works. It also now writes one byte at a time to CGA cards as I suspect some 'fake 6845' systems may not accept WORD port writes properly to $3D4/$3D5. (could also be a 8086 vs. 8088 difference)

The second file, PAKUT1JR.EXE is rewritten to be optimized for tandy/jr sound ONLY and uses the 160x200 tandy/Jr graphics mode -- which should at least render properly on the Jr. though I don't know if it's going to be fast enough to handle it given it's basically twice as many bytes to write to memory (and Jr. memory is, well...). It basically runs scanline doubled so it looks the same, running actual 200 high would make the sprites too big to be blitted to the screen quickly enough since it would double the size of both back-buffers and all sprites.

I was surprised how little time it took for me to write the port to that 160x200 mode once I figured out it's a $8000 interleave per scanline. (the 320 mode is for every four scanlines, 640 is every eight -- gotta love that consistency)

Kinda-funny in a way, you'd half expect the interlacing to be the same memory size and not shrink with the pixel count... Though I think that's the 16k per CGA block limitation kicking in.

[jmetal88]

Alright, my PCjr really hates the new paku.exe for some reason. The image gets all quadruple-sized and overlaid on top of itself.

I've had another program do that as well - one that was in the PCjr club archive. Kinda makes me wonder if something might be wrong with my video hardware, since two text-mode programs which are supposed to work on the PCjr do that.

I'm hoping someone else posts results soon, so I can see if there actually is something wrong with my Jr.

EDIT: It's funny, though, even though I can barely make out what's on the screen, what I can see isn't blinking, as it should.

[jmetal88]

The Jr/T1000 version works perfectly on my machine, by the way.

Although I am overclocked to 8mhz, so I'm sure I'm not the best performance indicator for a stock PCjr.

[jmetal88]

Alright, if you come out with anything else, I won't be able to test it until tomorrow. I think my V20 died - I turn on the PCjr and I get a white screen and a buzzing noise. Same as when the CPU is removed. I think it's either that, or I've accidentally shorted something out.

I've got a couple of spare 8088s at home I can try out, but if the V20 is dead, I won't have access to my ZIP drive.

[deathshadow60]

Alright, if you come out with anything else, I won't be able to test it until tomorrow. I think my V20 died - I turn on the PCjr and I get a white screen and a buzzing noise. Same as when the CPU is removed. I think it's either that, or I've accidentally shorted something out.

I've got a couple of spare 8088s at home I can try out, but if the V20 is dead, I won't have access to my ZIP drive.

Sounds like you've got yours rigged to the hilt -- so a short out isn't too unlikely... Though from what I remember just having the sidecar was running the risk of frying it -- like the RAM packs on the old Sinclair or Trash-80 MC-10... or the original TRS-80 model 1 expansion interface.

WAY off topic:
I'm sitting here looking at my testbed tandy 1k's, and I was thinking on putting a V20 in them and pimping them out with all sorts of extra hardware -- but find myself asking "why?"

The POINT of having a retro-computer is to have the original computer in it's original working order... Why turn it into something it's not when I have a i7 870 rig sitting next to it? That's all I keep thinking when I see the PC Jr to Tandy mods -- at that point why not just get a Tandy, you can usually pick up a working 1K for around $50... which is usually less than all these changes to make the Jr. more compatible does.

But then I remember how much fun I have digging around in a machine's guts... Like what I've been doing with my original 4k Coco giving it the extended color basic ROM, a CoCo 2 extended keyboard, composite out, inverse video, 64k on a board designed for 16 max, etc, etc...

To hack or not to hack...

[jmetal88]

I think it's a lot of fun to try making old computers do things they weren't meant to do.

Anyway, I got the Jr home, did some troubleshooting, and thankfully, it's just a short. I heated up the solder joints on my memory upgrade again, and scraped off some of the loose bits, and the machine booted right up! I need to start being more careful with my soldering iron, I guess.

[jmetal88]

I've attached a JPEG showing what I see with the latest PAKU.EXE. It's moving around as if someone messed up the VHOLD.

Can somebody else give it a shot and see if you get the same results? I'd like to know if I have a faulty video mode or something.

PAKUT1JR.EXE works fine.

[deathshadow60]

I'm going to re-read the section explaining what registers do what on the Jr as well. I made a few changes that may have gone a bit too far in trying to make it Jr. specific.

-- edit --
http://www.cutcodedown.com/retroGames/a ... KU1_33.rar

That's had a lot of the Jr. changes removed and instead just plays with that one $3DA setting... I'm hoping that's all it takes to make it work right.

I was also failing to read the register to reset the flip-flop... the proper approach being:

Code: Select all

procedure juniorGate(addr,value:byte); assembler;
asm
   mov  dx,$3DA
   in   al,dx { read and discard, resets flip-flop to address write }
   mov  al,addr
   out  dx,al { set address }
   mov  al,value
   out  dx,al { write data }
end;

Shades of programming adlib audio.

Off topic again:
Been reading through that Tech manual for fun -- in particular the Jr. BIOS, some really #DDD code in there... like the the check of the 8088 flags at the start of BIOS - waste of code... or the absurd number of near calls to subfunctions that are only called once in the BIOS (at which point lose the CALL's and speed it up 20-30%) though I did notice the Jr actually issues a vertical retrace interrupt -- that could be handy.

[jmetal88]

Perfect! I just ran the new paku.exe on my PCjr under DOS 3 with my RAM upgrade removed, and it plays and looks great!

There is one odd thing, that I also noticed in the other versions, and that is that after the program starts, there is a buzzing noise in the background. It disappears when I toggle the sound off then on. It's no big deal, I just thought you might like to know.