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by Mike
Wed Mar 07, 2007 5:08 am
Forum: Programming
Topic: Working with 3k
Replies: 32
Views: 5507

Is it worth making a VIC-20 program at all? You're shaking the foundations of this discussion forum. Now I am really torn. I like the 3k game I am now making, but it is... expanded memory. So much of my style has relied on the simplicity of unexpanded basic. I feel like I am cheating. Restraining y...
by Mike
Wed Mar 07, 2007 2:06 am
Forum: Programming
Topic: Working with 3k
Replies: 32
Views: 5507

How many self defined characters do you need? With 8K it is still possible to put a small number of them into addresses 680..767 (chars 85 to 95), and 832..1023 (chars 104 to 127). That are 35 characters. You then issue POKE 36869,200 to activate these characters, and keep the screen at 4096. Michael
by Mike
Wed Mar 07, 2007 1:46 am
Forum: General Topics
Topic: Original VIC-20 Cassettes
Replies: 13
Views: 6051

Jeff-20 wrote:Blue Meanies is a great example of line crunching. How did the programmer crunch full line RETURNs inside PRINT statements?

Hmm...

Code: Select all

1 PRINT"AMB"
POKE 4104,13
RUN

:wink:

Greetings,

Michael
by Mike
Thu Mar 01, 2007 2:01 am
Forum: Programming
Topic: Confession: I don't understand Trigonometry
Replies: 19
Views: 5817

Re: Confession: I don't understand Trigonometry

I'm not really sure, but I suspect I will need Trig to get the job done. No? Yes. Probably the easiest way: 10 POKE 36879,8:PRINT "{CLR}" 11 FOR D=0 TO 359 STEP 5 :REM angle in degrees (0 .. 360) 12 R=2*{PI}*(D/360) :REM convert angle to radians (0 ...
by Mike
Mon Feb 19, 2007 7:10 am
Forum: General Topics
Topic: If you could have changed one thing about the VIC...?
Replies: 90
Views: 32100

But ON GOTO is even more powerful on e.g. Sinclair Basic. If I remember correctly, it lets you use formulas instead of individual variables: ON B/(A-20) GOTO 10,21,23,72,44 This also works on the VIC. One might question what kind of spaghetti code the program consists of if you need those c...
by Mike
Mon Feb 12, 2007 8:33 am
Forum: Other Systems
Topic: The poor forgotten Commodore 128
Replies: 27
Views: 6506

I skipped the C64, and instead bought the C128. So I used the 64 mode to play games, the 128 mode to program. Best of both worlds. ;)

Michael
by Mike
Mon Feb 12, 2007 6:27 am
Forum: Programming
Topic: Multicolour mode on VIC v C64 and 264-series
Replies: 1
Views: 904

ad 1) correct ad 2) you can't activate both extended colour and multi-colour mode at once, TED and VIC-II will give you an entire black screen. The article in Wiki (3 of 4 colours unique to each char position) applies to the multicolour hires mode (as opposed to multicolour text mode) of the VIC-II....
by Mike
Mon Feb 05, 2007 1:24 am
Forum: Programming
Topic: Graphic/Picture File Formats on VIC-20
Replies: 53
Views: 11198

Fine! :) I did mention Brickshop here in another thread.

Michael
by Mike
Fri Feb 02, 2007 2:47 am
Forum: Hardware and Tech
Topic: Sound trouble
Replies: 11
Views: 2157

I found this program on the web that I tried I remember the pokes for the VIC-20 sound. The VIC had 4 voices, 36874, 36875, 36876, and 36877. [...] Setting 36878 to 255 would be max volume. So, something like this: [code snipped] would sound something like hitting piano keys. The sound would hit ni...
by Mike
Tue Jan 30, 2007 2:13 am
Forum: Programming
Topic: Graphic/Picture File Formats on VIC-20
Replies: 53
Views: 11198

The following C program converts a 80x192 *.pgm file to a multi-colour MINIGRAFIK bitmap, that uses ordered dither. I use IrfanView beforehand to first crop the image (Aspect width:height ~= 1.4), then to scale down the image (with resample/bell filter). The comment inside the PGM needs to be remove...
by Mike
Mon Jan 22, 2007 1:13 am
Forum: Programming
Topic: VIA Timer 1 or Timer 2?
Replies: 7
Views: 2444

If you're going to use an NMI to update the clock, the only option is VIA 1, which controls the RS 232 interface. Here, timer 1 is shared with tape operation, so you'd stick with timer 2. VIA 2 is connected to the IRQ line, and controls keyboard, cassette, and disc drive. The most sensible solution ...
by Mike
Fri Jan 19, 2007 1:51 am
Forum: Programming
Topic: Display of TI$ in border (unex. or +3K)
Replies: 19
Views: 6061

The last part of the routine reads and debounces the status of the RUN STOP key (i.e. whether it is depressed, or not).

Greetings,

Michael
by Mike
Tue Jan 16, 2007 2:41 am
Forum: Buy, Sell, and Trade
Topic: New Low-Cost 32k RAM expanders
Replies: 98
Views: 13274

My variant: POKE642,32:POKE644,58:POKE648,30:SYS64818 Of course, the RAMTOP problem remains. Fixing the pointer in the IRQ is not guaranteed to work: If I write-protect RAM for characters, I write 'POKE 55,0:POKE 56,28:CLR' or similar. CLR then sets 51/52 (String TOP) from 55/56. Most probably the I...
by Mike
Fri Jan 12, 2007 6:28 am
Forum: Programming
Topic: Hires Graphics
Replies: 111
Views: 46982

This is number theory. The numbers from 0 to 65536 form a field, and 75 is relative prime to 65537 (the number of elements in the field). That means: k S = 75 mod 65537 k is a sequence of numbers from 1 to 65536, which all appear exactly once (as you've guessed). The choice of the base 75 results in...
by Mike
Fri Jan 12, 2007 6:10 am
Forum: Emulation and Cross Development
Topic: Vice monitor and zero pages
Replies: 16
Views: 3874

Re: VIC Bitmaps

I'm surprised though [...] what difference would it make if it was 'onboard' RAM or 'external' RAM? The VIC-20 has split address busses for the VIC chip and the 6502. This is, because the 6502 doesn't have a Access Enable Clock signal, which could tri-state its address bus. But only the 6502 addres...

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