Denial WIKI change / addition announcement thread.

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carlsson
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Postby carlsson » Mon Mar 09, 2009 3:15 pm

Correct. You can adjust it internally a bit exactly which frequency you want, but no switch.
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Richard James
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Postby Richard James » Tue Mar 10, 2009 3:57 am

The PAL one I pulled apart the other week has a switch. Maybe not having a switch is country specific.
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carlsson
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Postby carlsson » Tue Mar 10, 2009 4:26 am

Was it a very early RF modulator? In recent years I've had at least two boxes: one black and one silver. Neither had a switch. On the other hand I also own a black NTSC RF modulator and I can't recall it having a switch neither?
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Richard James
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Postby Richard James » Tue Mar 10, 2009 5:08 am

It says (c)1981 on the circuitboard. Now that you mentioned it in the other thread how do i tell if it is not a NTSC one?

It came from a VIC20 purchased in Brisbane Queensland Australia. It says Philippines on two stickers on the inside and outside and inside (assume it was made there). It also says AUS 0/1 on both stickers which makes me assume it was a part intended for the Australian market.

I just googled for info on the company name "ASTEC international" apparently they still make electronics in the Philippines.
http://siva-ph1.jobstreet.com/_profile/previewProfile.asp?advertiser_id=34423

Unfortunately I did pull the thing to pieces to get the component video lead so without soldering it back together I can't work out the channels it uses.
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ral-clan
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Postby ral-clan » Wed Mar 11, 2009 8:00 am

Thanks for the addition of your pictures to the RF modulator article Richard.

I added A4000bear's S-VIDEO hack to the WIKI:

http://sleepingelephant.com/denial/wiki/index.php?title=S-Video_output

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ral-clan
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Postby ral-clan » Wed Mar 11, 2009 8:00 am

double post, please delete.

For some reason, although I am a moderator, I am not allowed to delete messages - even my own! I can see the delete "X" icon though, but when I click it all I get is "only an administrator can delete messages".

Carlsson explains: Only Jeff-20 can delete posts in General Topics. We moderators can split a topic into a subsection, then immediately delete that new topic. If we had a Moderators' FAQ, it might be the #1 question. :-D

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Postby Richard James » Fri Mar 13, 2009 6:39 am

Did some more work under BASIC flow control. How many GOSUB's deep can the VIC20 execute? The answer I have is 23, I don't know if that is correct. :?:

Hopefully I will be able to work through some more BASIC this weekend.
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carlsson
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Postby carlsson » Fri Mar 13, 2009 7:17 am

It would appear so:

10 I=0
15 I=I+1:GOSUB 15

I=24 when the program crashes out, so 23 successful loops. That is independent of memory expansion as the return value of each GOSUB is stored on the stack.
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Postby rhurst » Fri Mar 13, 2009 7:22 am

carlsson wrote:... so 23 successful loops. That is independent of memory expansion as the return value of each GOSUB is stored on the stack.

If I recall correctly, I believe FOR ... NEXT loops are also stored on the stack, so GOSUBs from within FOR ... NEXT loops, or calling a subroutine that has FOR ... NEXT loops, will also limit how deep you can go.

So, the same could probably be said with the use of FN calls, too.
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carlsson
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Postby carlsson » Fri Mar 13, 2009 11:01 am

Yes, FOR-NEXT is stored on the stack and can be simulated in this way:

10 FORA=1TO10:POKE4102,PEEK(4102)+1:GOTO10

Note this is a self-modifying program for unexpanded VIC-20. It will bail out at FORJ=1TO10, which means it set up nine (A-I) nested loops but failed on the tenth.

Here is a FN test, which is a bit more complex because as far as I know the FN function normally can't assign values nor have any other side effects. That is why we define an USR function which simply increases the value of the first byte in the screen matrix:

10 DATA238,0,30,96,-1:A=673
20 READB:IFB<>-1THENPOKEA,B:A=A+1:GOTO20
30 POKE1,161:POKE2,2:POKE7680,0
40 DEFFNA(X)=USR(X)+FNA(X)
50 PRINTFNA(2)

It gets from "@" to "F" which suggests to me the FN function can be called recursively five times before giving up? Or rather, up to five different FN functions can be called in a chain.
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OCR ?

Postby Commander#1 » Sat Mar 14, 2009 8:07 pm

Also, the first SYS in the instructions in that article looks strange (it has an apostrophe in it). Is this valid, or an error from when the document was OCR'd (I can't remember where I got this text file).


ral-clan -

Just curious - what does "OCR" mean?

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ral-clan
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Re: OCR ?

Postby ral-clan » Sun Mar 15, 2009 5:12 pm

Commander#1 wrote:
Also, the first SYS in the instructions in that article looks strange (it has an apostrophe in it). Is this valid, or an error from when the document was OCR'd (I can't remember where I got this text file).


ral-clan -

Just curious - what does "OCR" mean?

Phil Potter.


Optical Character Recognition (software that converts text scans to ASCII).

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Screenshots added to S-video article

Postby Bacon » Mon Mar 16, 2009 12:33 am

I've added screenshots and some info to the article about modding the VIC-20 for S-video output.
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ral-clan
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Postby ral-clan » Mon Mar 16, 2009 11:45 am

New article on paddle controllers:

http://sleepingelephant.com/denial/wiki/index.php?title=Paddle

and the associated game controller port:

http://sleepingelephant.com/denial/wiki/index.php?title=Game_controller_port

also, just wanted to point out the older joystick article:

http://sleepingelephant.com/denial/wiki/index.php?title=Joystick

Some examples of BASIC code to read joystick and paddles would be nice, if anyone cares to add it to the relevant articles.

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Mike
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Postby Mike » Sat Mar 28, 2009 7:23 pm

ral-clan wrote:Some examples of BASIC code to read joystick and paddles [...]

I've put small examples in these two articles, pointing out the necessity to bracket PEEK(37152) with two POKEs to address 37154, and how to counteract the paddle jitter.

Greetings,

Michael


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