Paper tape and 8th bit?

Ken kenzolist at counterfolk.com
Sat Aug 26 19:08:42 CDT 2006


At 07:33 PM 8/26/2006 -0500, Dave Dunfield wrote:
>0000  0D 0A 00 00  0D 0A 00 00  30 20 52 45  CD 0D 0A 00  ........0 RE....
>0010  00 32 20 52  45 CD 20 20  3C 3C 3C 20  20 42 41 53  .2 RE.  <<<  BAS
>0020  49 43 20 54  4F 20 56 44  4D 2D 31 20  4C 49 4E 4B  IC TO VDM-1 LINK
>0030  20 50 52 4F  47 52 41 4D  20 20 3E 3E  3E 0D 0A 00   PROGRAM  >>>...
>0040  00 34 20 52  45 CD 0D 0A  00 00 36 20  52 45 CD 20  .4 RE.....6 RE. 
>0050  20 20 20 20  20 20 50 52  4F 43 45 53  53 4F 52 20        PROCESSOR 
>0060  54 45 43 48  4E 4F 4C 4F  47 59 20 43  4F 52 50 2E  TECHNOLOGY CORP.
>0070  0D 0A 00 00  38 20 52 45  CD 20 20 20  20 20 20 20  ....8 RE.       
>0080  36 32 30 30  20 48 4F 4C  4C 49 53 20  53 54 52 45  6200 HOLLIS STRE
>0090  45 54 0D 0A  00 00 31 30  20 52 45 CD  20 20 20 20  ET....10 RE.    
>00A0  20 20 45 4D  45 52 59 56  49 4C 4C 45  2C 20 43 41    EMERYVILLE, CA
>00B0  4C 49 46 4F  52 4E 49 41  20 20 20 39  34 36 30 38  LIFORNIA   94608
>00C0  0D 0A 00 00  31 32 20 50  52 49 4E D4  0D 0A 00 00  ....12 PRIN.....
>00D0  31 34 20 41  24 BD 22 28  48 45 58 29  20 49 53 20  14 A$."(HEX) IS 
>00E0  59 4F 55 52  20 4C 41 53  54 20 41 44  44 52 45 53  YOUR LAST ADDRES
>00F0  53 2C 20 49  4E 50 55 54  3A 22 0D 0A  00 00 31 36  S, INPUT:"....16
>
>This is the line '0 REM', however the 'M' has the eight bit set, which makes
>the code CD instead of 4D. You can see this in the remaining comments
>which are visible as well. However the 'M' in 'EMERYVILLE' appears with
>the high bit clear.
>
>You can also see that the 'T' in 'PRINT' has the high bit set.
>
>This is supposed to be loaded under Altair BASIC somehow (I'll have to
>dig out the Altair BASIC manuals and if it sheds any light) - I thought that
>perhaps this in an internal representation, and that AB sets the high bit
>on the last character of reserved words ... except that 'INPUT' does not
>have the high bit set on it's last character...


It seems consistent that 'INPUT' wouldn't have the high bit set there.  The pattern seems to be that the high bit is set on the last character of every BASIC keyword.  In the context in which 'INPUT' appears in this code fragment, it's part of a quoted string, not a keyword.

Also note that the '=' in line 14 (A$="(HEX....) has the high bit set as well (thus appearing as BD instead of 3D).  = is also likely being treated as a BASIC keyword in this context.

- Ken 




More information about the cctalk mailing list