Re: BASIC OS for the PC

From: Michał Pleban <>
Date: Wed, 21 Dec 2016 11:29:39 +0100
Message-ID: <>

Baltissen, GJPAA (Ruud) wrote:

> Edit: I wrote the above yesterday. Your remark about the 254 bytes kept ringing a bell. When I checked things in the evening I found out why. I still use the link bytes but not in the sectors them self but in the BAM. In fact something like the FAT does. 

So yes, basically you don't have a BAM anymore but more something like
FAT. So your filesystem is not that similar to CBM after al ;-)

> Very good question. So far none. But there is a simple reason for that: I still don't understand what garbage collection exactly does. I

Maybe garbage collection is not the best term. I think "memory
defragmentation" might be better.

Basically, when you create string variables in memory, they take some
space. For example:

A$ = "aaaaaaaaaaaaaaaa"
B$ = "bbbbbbbbbbbbbbbb"

Suppose you later change one variable:

A$ = "cccccccc"
B$ = "bbbbbbbbbbbbbbbb"

Now you have 8 free bytes between A$ and B$. If you want to create a
third variable which is 8 bytes long, it's fine. But a 9-byte variable
will not fit there so the free space remains unused.

As the program is running and changing its variables, there are more and
more such small free holes in memory. You need a program that compacts
all these small holes into one large free space.

> For the moment I'm happy with my simple 8088 :)

Will it run on a CBM-II with a 8088 card? :-P


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Received on 2016-12-21 11:00:02

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