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About algarsoft

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    Combat Commando
  1. Yes, nice suggestion! After more than 30 years I didn't recall that the counter is incremented BY TWO, not by one. (To be honest, I didn't even recall if the counter was incremented or decremented and so, I felt safe with >8000) As a matter of fact, I've checked the system ISR in ROM and (once decided that the current interrupt is from VDP) it will land at: 0A8A LWPI >83C0 ; Interrupt workspace 0A8E INCT 11 ; Increment BY TWO counter 0A90 JNE >0AA8 ; jump if counter is not 0 0A92 .... ; blank the screen if ==0 .... 0AA8 LWPI >83E0 ; GPL workspace .... ; increment tick at @>8379 ; call user ISR, if any so it's definitely more efficient (and without potential side-effects) performing a: SETO @>83D6 than a clumsy: LI R0,>8000 MOV R0,@>83D6 The forced >FFFF will always be >0001 at the next vertical screen blank interrupt, thus disabling the system screen saver. (Moreover, the game has ITS own screen saver for user inactivity) Thanks a lot Lee...
  2. I don't thik this is the original SolidState version, but an hacked OPT5 version for PEB/disk drive... Maybe, who originally ripped the cartridge forgot the blanking and scratch-pad init...
  3. .dsk file finally attached. Sorry, could not spot the problem. PACMAN_FIX.zip
  4. the .dsk attachment was missing. I Retry with this....
  5. Hail to the TI-99 community! I've recently purchased a CF7+ with parallel interface and I've reviewed my OLD TI99 programs. I've learnt my first assembler on the TI-99 when I was 13. I've found here on atari age, the links to a lot of interesting stuff, among which the Atari port of PacMan, by Howard E. Scheer. In my humble opinion, It's the BEST port of an arcade for the TI-99 and it's VERY playable and responsive (even with the original TI Joysticks). Played on "real iron" it's VERY fun and addictive! Unfortunately, the disk version had two annoying bugs: 1) The high score was trashed at startup with a very high number, not allowing ANY user score to be recorded. 2) The screen flickered every now and then while playing and sometimes the game crashed after the flicker. I've studied in my spare-time the binary and found that: 1) The high score was trashed because the scratch-pad area was not properly initialized by the loader (originally it was a Solid State Cartridge) 2) The original system interrupt routine blanked the screen every 9/10 minutes without pressing a key and, sometimes, trashed some VDP registers restoring the screen. So I've simply added a by-pass fragment on startup that clears the scratch pad area and installs an user ISR that loads the blank screen count-down at >83D6 with >8000, thus disabling the screen blank for keyboard inactivity. Now You can load the binary with an option 5 loader (E/A, XB, Beaxs) and play the game without problems. You can use the .dsk attached: with E/A: choose 5 and then type DSK1.PACMAN with XB: let the XB loader run and type DSK1.PACMAN By the way, my personal hi-score (played on a real TI99) is 170.460 points at the 16th screen. Anyone knows the official one? Cheers!
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