Dinosaurs of Computing

The Dinosaurs episode of This Developer’s Life struck a chord with me. Not because of Fortran or Dataflex although hearing about developers dealing with small memory constraints or attempts to convert an archaic piece of code into something shiny did make me grin stupidly.

No, there’s a bit about the Commodore 64 in there and some great SID chip music throughout the podcast. That sealed the deal for me! :)

If you thought software development was hard …

shot4-550x412

You should read about the development of a Ludum Dare entry called Ponk.

It’s a C64 version of Pong, developed on a real C64 with only a C2N datasette to save code. Back in the day I was lucky enough to have a 1541-II disk drive. I can’t imagine how painful it must have been working with a slow and unreliable cassette.

datassete

In the end he couldn’t transfer his game to a PC so he had to take screenshots of his game and OCR them, hand checking every byte. I did something similar about 20 years ago when I was tinkering with a C64 to Amiga cable and needed to somehow transfer a C64 programme from the Amiga to the C64 to do the transfer .. Painful.

playing

Wow. Well done Sosowski. (via Indiegames)

A Red Storm brewed some Beatles

Earlier this evening while listening to “I am the Walrus” by The Beatles my wife asked how I knew that song. She wasn’t familiar with it you see. I replied that I had heard it used in a Commodore 64 demo and then spent the next few minutes wracking my brains for the name of that demo.

I thought it might have been made by Nato, and the title started with “Red” but nothing jumped out at me. Then I thought of Fairlight but again, nothing there except some of their demos were produced with another group, Triad! Yes, that was it!

Triad created Red Storm in 1992, it’s not the most technically sophisticated demo but it’s one of my favourite C64 demos ever. It has some nice effects but I really loved the Zoo TV inspired visuals and poetry. The music was great too, but I didn’t realise it was covers of Beatles music. Granted, it was done on a C64 SID chip so it has that 8 bit sound but it still sounds great. ‘Course, that might just be my nostalgic ears playing tricks on me.

What do you think? Yay or Nay?

C64: Wanted Dead or Alive

Bon Jovi’s “Wanted Dead or Alive” as played on a real Commodore 64. The song was digitized on an Amiga, downsampled to 4 bit audio and copied onto a 3.5″ inch disk that the Commodore 1581 drive could read from. The song data was streamed in realtime from the drive to the tiny 64Kb of memory in the computer and fed to the SID chip for our aural delight. I presume the screen has been blanked to save processing power, or the data for the sample gets dumped into screen memory.

This did require an Amiga with the Perfect Sound digitizer. I hooked up the CD player to the digitizer and then using a custom routine on the Amiga, my brother would convert the data to a 4 bit sample. Then we used a null modem cable and Novaterm with a cartridge port adapter to transfer the data to a 1581 floppy. Quite a bit of work went into this.

20 years ago I recorded my own voice onto a cassette saying the word “Ozone” (the name of my demogroup) and I figured out how to sample my voice using the Commodore cassette deck hooked up to the C64. I can’t remember now what memory register it used, I’ll have to search my disk images or examine a C64 memory map one of these days. The quality was terrible but if you knew what was being said you could make it out. It had to be kept short because I’d ran out of memory! I think I used it in the last part of my demo “Awareness of Reality”. (via)

Happy Birthday Commodore 64!

issue 50 of Zzap 64!
Issue 50 of Zzap! 64

The Commodore 64 is 30 years old this year and it went on sale in August 1982 so I think it’s about time I wished it a happy birthday. Back then I was messing on a Commodore Vic 20 (or more likely it was 1984 or so), then I had a Speccy and I didn’t get my hands on a C64 until 1989. It was already declining somewhat but it still had a few years of life left in it. Issue 50 of Zzap! 64 was the first issue of that famous magazine I owned. My brother and I bought it in Paul’s Street Shopping Centre! The newsagent is long gone but I have that issue around here somewhere ..

Matt Allen visited a primary school and a secondary school and asked kids there what they thought of the Commodore 64. I don’t think they were impressed by loading errors and long loading times. He probably should have brought a 1541 disk drive and an Action Replay cartridge!

Continue reading Happy Birthday Commodore 64!

Prince of Persia: the Apple II source

It’s been a good few months for the 8 bit versions of Prince of Persia. Last October saw the release of a C64 version. Yesterday the original source code for the Apple II version was uploaded to github! Read about how Jason Scott recovered that source code from 20 year old disks (similar to what I did recently!)

The game was originally written in assembler so the source code was already out there. How? Machine code is the language a machine understands and assembler is a human representation of that machine code. For example, the machine code “A9 00 8D 20 D0″ is actually this more readable assembler: (that inserts the value 0 into the memory location $D020)

LDA #00
STA $D020

The assembler code released yesterday goes one step further. It uses labels, variables and comments. See BOOT.S as a good example. Variables are defined at the top and labels are used throughout making it a lot easier to deal with moving and adding code around. Look for the text “skewtbl” where you’ll find a simple loop that reads in data from memory and inserts it into 2 registers.

:0 ldy sector
 lda skewtbl,y
 sta $3d
 lda sectaddr,y
 beq :1
 sta $27
:rdsect jsr $005c
:1 dec sector
 bne :0

 lda SLOT
 jmp $900

skewtbl hex 00,0d,0b,09,07,05,03,01
 hex 0e,0c,0a,08,06,04,02,0f

sectaddr hex 00,09,00,00,00,00,00,00
 hex 30,31,32,33,34,00,00,00

Jordan Mechner puts it more poetically:

Non-programming analogy: Video game source code is a bit like the sheet music to a piano sonata that’s already been performed and recorded. One might reasonably ask: If you have the recording, what do you need the sheet music for?
You don’t, if all you want is to listen and enjoy the music. But to a pianist performing the piece, or a composer who wants to study it or arrange it for different instruments, the original score is valuable.

Props to this Slashdot post for the extra links. Also worth a look is the development diary of the C64 version and there are videos showing how the game was made back in 1985!