exxos's Atari, Amiga & retro forum

mrbombermillzy wrote: 23 Mar 2022 19:10 Well, I've just had a look at a YT vid of it and it's pretty darn good for a VIC20!

That must have been harder to code than playing the game on nightmare. :)

I can only imagine!

Hmm, wondering if the VIC in the VIC is not quite as it once was.

Here is the Doom title screen, first from the VIC-20, then from an emulator:


And the same from the game menu screen:



The colours on the real machine are very muddy, though the actual BASIC prompt is fine. I started looking at this because the colours on Super Lander are obviously not right either, and somebody commented on my VIC Doom post on FB that the colours looked wonky.

Looks like some fixing up remains.

Hmm, OK, so NoS VIC 6561, are available, but before I order one, I think I'll pull the current one out and give things a clean up before I order, but it seems like there are known fails for these items where the colours muddy up.

Oh dear.

I feel your pain as I'm having similar problems myself (just not on a VIC) :(

mrbombermillzy wrote: 24 Mar 2022 11:43 Oh dear.

I feel your pain as I'm having similar problems myself (just not on a VIC) :(

Oh no, what's your issue then?

rubber_jonnie wrote: 24 Mar 2022 11:49 Oh no, what's your issue then?

Don't tell anyone, as I haven't posted the test results yet :lol: but the twin shifter board, after bypassing the (alleged) correct resistances from the RGB lines does not seem to have made any difference to colour brightness/contrast.

Like I said, I have to check it properly later, but, from an initial glance... :(

mrbombermillzy wrote: 24 Mar 2022 12:00

rubber_jonnie wrote: 24 Mar 2022 11:49 Oh no, what's your issue then?

Don't tell anyone, as I haven't posted the test results yet :lol: but the twin shifter board, after bypassing the (alleged) correct resistances from the RGB lines does not seem to have made any difference to colour brightness/contrast.

Like I said, I have to check it properly later, but, from an initial glance... :(

Ah, ok fair enough :)

Ok, so a little while ago I bought one of these:


And up to now I have only really tried the RAM aspect of this, getting the max amount that can be used by the VIC-20. That was cool because it meant I could run Doom :)

So, given todays project of looking at the OPD keyboard wen up in smoke (Literally, thanks RIFA!!), I decided to have a play with this instead and see if I could make the multi ROM capability work.

Basically the card takes a 27256 (32Kx8) eprom and you should be able to burn 4 x 8KB images and then select the bank to use using the DIP switch.

I initially burned the same image 4 times and was able to get 4 ROMs, Omega Race, Choplifter, Cosmic Jailbreak and Frogger to run individually.

I then turned to HxD to build some 4 ROM images using those known good single images. Success has been limited, in that I can get 2 out of the 4 games to run from that ROM image, so a little more work needed, but hell, it's progress :)

Unfortunately, the documentation is limited to a tiny strip of paper that doesn't help a lot, so off to see if I can find a little more via Google. I suspect my own limited knowledge of the VIC-20 is also at play here, and it may simply bee that some of these ROMs need to be in a certain memory space to work.

Time to break out my Google Fu!

Probably "teaching granny to suck eggs" here, and I apologise if I am repeating something you are already doing, but from terrible, terrible personal recent experience, are you making sure all the ROMs have been resized / padded to be the right size before you join them?
( I learned that the hard way. Some ROMs I were joining were a byte or two smaller than they needed to be. Of course when I concatenated them, every ROM after the incorrect one was now no longer byte aligned and it just got worse and worse from there on out.
Ended up using a hex editor to manually pad all the ROMs to the exact right length and reburn the ROM. Madness!
(Mind you, this was for a Microbee and for a piece of hardware I had developed for myself)

Chesh

Cheshire Noir wrote: 25 Apr 2022 01:20 Probably "teaching granny to suck eggs" here, and I apologise if I am repeating something you are already doing, but from terrible, terrible personal recent experience, are you making sure all the ROMs have been resized / padded to be the right size before you join them?
( I learned that the hard way. Some ROMs I were joining were a byte or two smaller than they needed to be. Of course when I concatenated them, every ROM after the incorrect one was now no longer byte aligned and it just got worse and worse from there on out.
Ended up using a hex editor to manually pad all the ROMs to the exact right length and reburn the ROM. Madness!
(Mind you, this was for a Microbee and for a piece of hardware I had developed for myself)

Chesh

It's a good point, and though I do normally pad images out if needs be, these are all saying they are 8k from the get go.

However I think it's definitely worth checking, and since the VIC-20 is new to me it is entirely possible that there is something else I'm missing.

I need to see if the site on the card has any more information about the dip switches too.