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Forums > CSDb Entries > Release id #187773 : Alternate Reality - The City +11D
2020-02-15 17:47
jcompton

Registered: Feb 2006
Posts: 70
Release id #187773 : Alternate Reality - The City +11D

With a dramatically improved saver and a trainer, it is now much much easier to live long enough to stumble into the original game's bugs!

Notably:

- Certain potion effects (Potions of Protection +1/+2) modify the wrong area of memory and may not actually provide any benefit whatsoever.

- These potion-related memory trashes can affect playfield graphics like door labels and mountain backdrops.

- Too many potion effects will crash the game!

- Banks may exhibit erratic behavior at times.

- Upon transitioning from a building back to the game map, the game sometimes "forgets" whether you are outdoors or in an "enclosed area."

- The game mostly hides the mirroring of door labels, but forgets to do so in certain types of Enclosed Areas, so words like "SHOP" and "TAVERN" will appear reversed on the bottom of the door.

- In silent interiors there's a horrible buzzing sound when the SID should probably just be turned off.
 
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2020-02-25 16:10
Fix

Registered: Feb 2003
Posts: 54
@fix Yes - for example SD2IEC.

I know of several IFFL loaders that support SD2IEC.
Not 2-bit fastload, but it supports it.

Also I know there is support for save too.
2020-02-25 16:13
Krill

Registered: Apr 2002
Posts: 2839
Quoting Fix
I know of several IFFL loaders that support SD2IEC.
How would they seek backwards within the IFFL file (via KERNAL calls, presumably)? Simply close it, open it again, then read and discard bytes until at the desired position?
2020-02-25 16:44
Fix

Registered: Feb 2003
Posts: 54
Quote: Quoting Fix
I know of several IFFL loaders that support SD2IEC.
How would they seek backwards within the IFFL file (via KERNAL calls, presumably)? Simply close it, open it again, then read and discard bytes until at the desired position?


There is no seek command, we had another solution.
It's 2 years ago I touched that code.

If I remember right there is another command you can use with SD2IEC to solve that problem.
2020-02-25 16:56
Krill

Registered: Apr 2002
Posts: 2839
Ah, there is a command to set the position within an open file.
Didn't know that. :)
The syntax to position within any regular file is as follows:

OPENlf,dv,15:PRINT#lf,"P"+CHR$(ch)+CHR$(lo)
[+CHR$(mlo)[+CHR$(mhi)[+CHR$(hi)]]]:CLOSElf
Where:

Variable	Description
lf		the logical file number for the command channel
dv		the current device number of the sd2iec
ch		the channel of an open file in which to move the position *
lo		the (0th) low byte of a 32–bit position
mlo		the (1st) mid–low byte of a 32-bit position (optional, defaults to 0)
mhi		the (2nd) mid–high byte of a 32-bit position (optional, defaults to 0)
hi		the (3rd) high byte of a 32-bit position (optional, defaults to 0)
That somewhat mitigates the compatibility argument.
2020-02-25 17:58
Burglar

Registered: Dec 2004
Posts: 1031
Quote:
@burglar How do you do it if you don't scan?
Quote:
You scan to the required file on demand, building the track/sector/offset table piece-wise, which is what Burglar did (if i got him right).
heh, sadly no, that would be smart :)
nah, I took the quick&dirty route, I just cache scan result on track 18 sector 18. this allowed for a quick recover after saveing a game, I actually just "rescan".
in other mods of my iffl, I reserve first sector for highscore and use a safe 1bit irq friendly save routine. don't wanna hassle with BAM ;P
2020-02-25 21:01
MagerValp

Registered: Dec 2001
Posts: 1055
Quoting Krill
fully-random file access in some hypothetical malicious game

That's really just your average rpg or adventure game :)
2020-02-26 00:48
Krill

Registered: Apr 2002
Posts: 2839
Quoting MagerValp
Quoting Krill
fully-random file access in some hypothetical malicious game

That's really just your average rpg or adventure game :)
And here i was thinking that the average RPG/adventure game would be based on some kind of decision tree and also limit the amount of disk juggling by not going full random. :)
2020-02-26 07:26
sailor

Registered: Jan 2002
Posts: 90
Just like Krill mentions, there is support for SEEK in sd2iec. I use it in JaffyDOS V1.3 Kernal for SD2IEC for the mkd64/71/81 commands.

..and with that said, I did a quick'n'dirty convert of an old release into "sd2iec iffl" and it runs ok (no surprise).. well, it did not run on someone elses sd2iec but thats probably another discussion regarding firmware, hardware, dirty code, something.

A few considerations, you are stuck with kernal loading which depends on zeropages and vectors which you need to (re)store. IRQ will be lacking and having the loader up high in memory will be a problem. It will have its limitations.. and another loader to test with the game.

However, since you are in kernal you can choose to have the savefile handled inside IFFL or separate file by standard load/save calls... and then you need a savefile export/import to the native IFFL.. and.. and.....

Interesting discussion though :)

Edit: There was discussion about implementing native n0sd0s-iffl loadersupport into sd2iec when some strange pirate-game was released.. A few flavours of n0sd0s exists, so it'd need to emulate multiple drive-side code.. not sure if there is space for more loaders in sd2iec.
2020-02-26 08:10
Krill

Registered: Apr 2002
Posts: 2839
Quoting sailor
IRQ will be lacking
Ah, with minor re-implementation of some KERNAL calls, you can play a standard SID tune glitchlessly during KERNAL load or save. =) The protocol on the bus is still the same. (Most likely not an option for cracks, of course.)
2020-02-26 09:11
Bacchus

Registered: Jan 2002
Posts: 154
@burglar We swap out scan tables to a sector on disk before saving on Herakles. So if the disk is write protected ours wouldn't run I guess. I assumed your version would be the same.

Also the general logic in normal IFFL (not ULoad - that's an exception) is that the drive holds the loader and scan tables. With the SD2IEC seek, you must port the scan table back to the computer.

I think the part where Krill gets it a bit wrong is that you rarely have any memory to play with. Squeezing in loader, depacker and the buffers they both need is normally quite a challenge. Adding a cache (scantable of just a cached scan result) is not really feasible.

/Bacchus
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