Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: COMMODORE 8032 FORTH
Message-ID: <697.UUL1.3#5129@willett.UUCP>
Date: 22 Mar 90 23:46:11 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 36

Category 1,  Topic 16
Message 17        Wed Mar 21, 1990
R.BERKEY [Robert]            at 23:00 PST
 
 
 Re: BLOCK and BUFFER

Charlie Hitselberger writes, 900320:

 > 2) Have the entire disk drive array behave as a contiguous virtual
 > memory plane.

This has been the conventional Forth approach in polyFORTH, and also fig-
FORTH.  Then they include a user variable OFFSET , a value that is added to
any block# input to BLOCK or BUFFER .  Such a combination is sufficient to
define DR8 in higher level.  A block and buffer driver I did had a table of
drives with each record containing:

 starting Forth block number
 ending Forth block number + 1
 read-block routine (uses a device-relative block number)
 write-block routine (ditto)

Another word DRIVE indexed that table.  Then, defining DR8 would become:

 : DR8   ( -- )   8 DRIVE @ OFFSET !   ;

This setup was sufficient to handle a couple of floppies with various
capacities, sector sizes, and formats; a small battery-backed-up ram disk, and
one large hard disk.

Robert

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