Author Topic: Infocom CPM games  (Read 439 times)

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Offline Mark_wllms

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Infocom CPM games
« on: 13:17, 17 June 21 »
I've downloaded some of the Infocom disk images from https://www.cpc-power.com/index.php?page=detail&num=2770
I had assumed that these were simply generic CP/M interpreters which run under CPM 2.2.
However, the disk contains three different interpreters for each game: e.g. for Hollywood Hijinx HIJI64.COM HIJI128.COM HIJI256.COM
I assume that the main programme (HOLLYWOO.COM) works out how much memory the machine has and then picks a suitable interpreter. I tried running HIJI128.COM directly on my CPC6128 (CPM 2.2) but there was some text corruption around the prompt.
Does anyone know how these worked?

Offline ComSoft6128

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Re: Infocom CPM games
« Reply #1 on: 14:50, 17 June 21 »
Both HOLLYWOOD.COM & HIJI128.COM look OK using CPM Plus, 2.2 might be the problem.


If I remember correctly 2.2 was only for the 464.
« Last Edit: 14:57, 17 June 21 by ComSoft6128 »

Offline Mark_wllms

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Re: Infocom CPM games
« Reply #2 on: 17:20, 17 June 21 »
Thanks. I downloaded the disk image that already had the CP/M 2.2. boot loader on it. I haven't tried it under CPM Plus.

I wonder if the HOLLYWOO.COM program detects which version of CPM is running and then chooses which version of the interpreter to run?

Offline zeropolis79

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Re: Infocom CPM games
« Reply #3 on: 18:55, 17 June 21 »
128 is one for a 6128 while 256 is for a PCW8256 onwards.

Offline Nich

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Re: Infocom CPM games
« Reply #4 on: 21:16, 17 June 21 »
I wonder if the HOLLYWOO.COM program detects which version of CPM is running and then chooses which version of the interpreter to run?

Yes. CP/M has a built-in function to return the version being used (either 2.2 or 3.1). However I don't know how the boot loader works out if it's running on a CPC or a PCW if version 3.1 (CP/M Plus) is detected. I've disassembled the code but I can't make any sense of it (but I'm definitely not a CP/M or a PCW expert ;)).

Offline zeropolis79

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Re: Infocom CPM games
« Reply #5 on: 21:42, 17 June 21 »
The EMS file on the disc can detect what machine it's runing on and won't load if it's the wrong one.


I once tried a PCW version of CP/M Plus on the 6128 but no go, likewise I tried the 6128 version on a PCW and that didn't load - I theorise it's because both are configured for each machine's screen resolution. Likewise, Plus wouldn't load on a 464 or 664 yet you can run 2.2 easily on a 6128.