Denial WIKI change / addition announcement thread.

Discuss anything related to the VIC
carlsson
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Post by carlsson »

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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Post by Richard James »

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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Post by carlsson »

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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Post by Richard James »

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/ ... r_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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Post by ral-clan »

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 ... deo_output
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ral-clan
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Post by ral-clan »

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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Post by Richard James »

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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Post by carlsson »

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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Post by rhurst »

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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Post by carlsson »

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 ?

Post by Commander#1 »

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 ?

Post by ral-clan »

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?

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Optical Character Recognition (software that converts text scans to ASCII).
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Screenshots added to S-video article

Post by Bacon »

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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Post by ral-clan »

New article on paddle controllers:

http://sleepingelephant.com/denial/wiki ... tle=Paddle

and the associated game controller port:

http://sleepingelephant.com/denial/wiki ... oller_port

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

http://sleepingelephant.com/denial/wiki ... e=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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Post by Mike »

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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