Re: Lisa Fonts

Rebecca,

I would be suprised if the Lisa font files were compressed. The Lisa had plenty of memory for RAM-based data. The ROM icon compression AFAIK was needed since the Lisa's 16KB ROM was full.

• David Craig

  ---

>
> Running the font files through that algorithm (with modifications to
> handle an arbitrary number of compressed bytes) gives me some
> interesting patterns, so it's a possibility. Of course just because
> it's interesting doesn't mean I'm barking up the right tree. A
> compression scheme like that would explain some of the patterns I'm
> noticing between the font file and the metrics file, but the bytes
> around the patterns are not consistent. Are there any compression
> scheme reverse engineering specialists around here? :)
>
> Is there a way to get LisaEm to produce trace logs, just to see what's
> going on?
>
> (Let's hope Google Groups lets this one through... :| )
>
> On Apr 6, 2:58 pm, Ray Arachelian <r..._at_email.domain.hidden> wrote:
>> Hi Rebecca,
>>
>> I'm not sure if this will help or not, however, the Lisa boot ROM
>> compresses its icons with some sort of RLE algorithm that stores a flag
>> in bit 0. Here's the source code to decode them - it's a bit obfuscated
>> because that's a fairly straight translation from the 68K assembly to C.
>>
>> Perhaps the same format is used for the fonts?
>>
>> Rebecca Bettencourt wrote:
>> > It
>> > doesn't contain a raw bitmap as far as I know. My current theory is
>> > that it is somehow compressed, since there are certain patterns
>> > mapping bytes in the font part to bytes in the metrics part. So I'm
>> > asking if anybody has documentation on the Lisa font manager, or
>> > disassemblies from when the Lisa is drawing text, or anything else
>> > helpful.
>
>
>

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. Received on 2015-07-15 16:37:14