Prince of Persia

reminisce about bbc micro & electron games like chuckie egg, repton, elite & exile

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mm67
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Prince of Persia

Postby mm67 » Sun Mar 01, 2015 8:37 pm

Prince of Persia was one of my favourite games of the early 90s (PC version that is).

Didn't find out until recently that it was originally written for the Apple II, i.e. in 6502 assembler.

Its creator Jordan Mechner has uploaded the original code to https://github.com/jmechner/Prince-of-Persia-Apple-II.

I couldn't find out anything about it ever being ported to the beeb, and wondered what it might look like, so spent some time last year writing some programs to convert the image files (results attached).

I might delve deeper if and when I have the time.

SSD file:
POP!.zip
Zipped up ssd file.
(17.06 KiB) Downloaded 79 times


A2B-P1 converts apple 2 to monochrome
A2B-P2 adds colour info
MODEX displays result. (Keys 1,2,3 cycle colours)
Attachments
pop in beebem.JPG
Beebem screenshot
mm67

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richardtoohey
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Re: Prince of Persia

Postby richardtoohey » Mon Mar 02, 2015 8:31 am

Thanks for posting - including the links - some interesting history there. :D

Is your code (I haven't looked yet :oops:) rendering objects from the game files? Or are you well on your way to making a BBC version?

Must admit I've never played the game on any platform - but I do remember all the excitement about the animation BITD.

Apple II screenshots are here (if you scroll down a bit) - if anyone else is curious (like I was) to see what it looked like on the Apple II.

http://www.mobygames.com/game/prince-of ... creenshots

paulb
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Re: Prince of Persia

Postby paulb » Mon Mar 02, 2015 11:25 am

richardtoohey wrote:Must admit I've never played the game on any platform - but I do remember all the excitement about the animation BITD.

Apple II screenshots are here (if you scroll down a bit) - if anyone else is curious (like I was) to see what it looked like on the Apple II.

http://www.mobygames.com/game/prince-of ... creenshots


The animation is rather nice, making me wonder what all the fuss was about Flashback several years later, especially given the original target platform of Prince of Persia.

It's interesting to compare the different screenshots. According to the source documentation, the Apple II graphics are fairly low resolution, but the version for the Amstrad CPC, which might otherwise be expected to be closest to the Beeb in terms of graphical capabilities, also seems to use a low resolution in comparison to other versions.

It is also informative that the minimum RAM requirement for the Apple II version is 128K and there's a certain amount of loading things from disk, although the Amstrad version appears to have been available on cassette, so I don't know how they managed there.

mm67
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Re: Prince of Persia

Postby mm67 » Tue Mar 03, 2015 12:27 pm

richardtoohey wrote:Is your code (I haven't looked yet :oops:) rendering objects from the game files? Or are you well on your way to making a BBC version?


No BBC version anytime soon - not by me anyway.

I've studied the code and some Apple II documentation, that's about it.

The files in the L directory on the disc are the original Apple hires screen files.

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tricky
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Re: Prince of Persia

Postby tricky » Tue Mar 03, 2015 1:50 pm

I would love to see it on a Beeb and was tempted, but the "tricky" bits would be fitting it in memory and tweaking the drawing code, neither of which excite me!

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CMcDougall
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Re: Prince of Persia

Postby CMcDougall » Tue Mar 03, 2015 7:12 pm

I had this game about 1992 on my first Compaq PC with 10mb HDisc :lol: , still got the copy on 3 1/2" floppy disc somewhere!

never thought much of it BITD, would rather play JCB Digger on my beeb :D

good start though Martin =D>
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trixster
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Re: Prince of Persia

Postby trixster » Tue Mar 21, 2017 7:05 pm

Did anyone ever take this further? Prince of Persia on the Beeb would be amazing.

PoP on the CPC6128 requires 128k of ram; PoP on the C64 requires a big cartridge to stream data from.

So perhaps a Master and MMC or Data Centre/IDE only version would be the best hardware to target? Of course, if it could be done on a 32k Beeb with multiple ssd's then that would be even more amazing!
A3020 | A3000 | BBC B + 128K RAM/ROM + 20K Shadow + RPi2 CoPro + VideoNuLA
BBC Master Turbo + DC | Atom | A1200 060 | A500 | Jaguar | A420/1
A4000/040 060 | Atari Falcon 060 | Saturn | PS1 | SNES | CPC6128 | C64 | 3DO

RobC
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Re: Prince of Persia

Postby RobC » Tue Mar 21, 2017 7:22 pm

trixster wrote:Did anyone ever take this further? Prince of Persia on the Beeb would be amazing.

PoP on the CPC6128 requires 128k of ram; PoP on the C64 requires a big cartridge to stream data from.

So perhaps a Master and MMC or Data Centre/IDE only version would be the best hardware to target? Of course, if it could be done on a 32k Beeb with multiple ssd's then that would be even more amazing!

I had a look at it a few years ago and I think I thought that 128K was about the minimum (and even then, the memory organisation was still a challenge). So, either a Master or B with a fair bit of sideways RAM.

paulb
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Re: Prince of Persia

Postby paulb » Tue Mar 21, 2017 8:37 pm

RobC wrote:
trixster wrote:Did anyone ever take this further? Prince of Persia on the Beeb would be amazing.

PoP on the CPC6128 requires 128k of ram; PoP on the C64 requires a big cartridge to stream data from.

So perhaps a Master and MMC or Data Centre/IDE only version would be the best hardware to target? Of course, if it could be done on a 32k Beeb with multiple ssd's then that would be even more amazing!

I had a look at it a few years ago and I think I thought that 128K was about the minimum (and even then, the memory organisation was still a challenge). So, either a Master or B with a fair bit of sideways RAM.


Or something like the Mega Games Cartridge but with a "moving window" arrangement within the sideways RAM/ROM area, a bit like what the Slogger disk interfaces did on the Electron to give PAGE &E00.

RobC
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Re: Prince of Persia

Postby RobC » Tue Mar 21, 2017 10:08 pm

Possibly - here's how the memory is laid out on the Apple II (according to the pdf that came with the source code):

Code: Select all

                        RAM            DISK
Image tables (sprites)
 Player                 30K            30K
 Enemy                  6K      x5 =   30K
 Princess & Vizier                     9K
 Background             13.5K   x2 =   27K
 Total                  49K            96K
 
Code                    48K            48K
Buffer space            8K
Music                   4K             6K
Level                   2.25K   x16=   54K (should be 36K? )
Screen memory           16K

TOTAL RAM               127.5K

Packed dblhires screens                 42K
Packed princess's room                  8.5K

TOTAL DISK SPACE                        252.5K

Whichever way you look at it, it would need a fair bit of sideways RAM (and/or possibly some sideways ROM if the sprite data is read-only).
Also, I'm not sure whether the sprite data would take up more memory when converted to the Beeb's display format.

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davidb
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Re: Prince of Persia

Postby davidb » Mon Mar 27, 2017 1:28 pm

I could imagine that most of that which is assigned to RAM could be put in ROM instead. At least on the Electron that approach would be feasible because you could put it in a cartridge with a 256K EEPROM these days. No, I'm not volunteering for anything. ;)


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