"File types"

On 8/28/2006 at 4:47 PM Don wrote: Are you asking, "Did any system keep file type information out of the file name?" The answer is "yes, several did". Here's part of a microcomputer floppy directory from a circa 1977 OS. Note that fiile dates show this disk was probably created around 1986 (yes, it's all in ASCII--no binary fields here): A$DIRECTORY 000000001500000016 SF 064032386 ACONFIG.SYS 000160001610000016 DV 000010199 AMT.PARTS 000170001702700017 DV 000010199 ADX85M26D03 000180004643600046 LV 000080483 AISAM.SYS 000470005814400058 SV 000080483 A$AUTOSTART 000620006201300062 PV 000080483 ARUN 000630009348700093 SV 000080483 AMTMENU 001120013036800130 OV 000010199 ALOCATE 001310014242700142 OV 000010199 A$SBA.C 001430014400000143 II 003 A$SBA.C@ 001450014800000145 MF 055 First column is the file name, the second is the file allocation and length information. The third column is the file type and the record type. S=System D=data, L=boot loader, P=profile, O=binary object, I=ISAM index, M=ISAM data (there are other types). The second characters is the type of record F=fixed, V=variable, I=index. The fourth column is the record length and the creation date. By convention, ISAM index files take the name of the data file, with an "at" sign appended, though there was no particular system requirement for this. If you enter the name of a file that didn't have the O file type, the system won't execute it. Similarly, you can't open a file with anything other than the DV attributes for text display or editing. ISAM files are handled by the ISAM manager and nothing else. You can't do ANYTHING with S or L type files, not read them, not write them directly. I've seen other systems from the 70's with this kind of directory information. However, the idea of a file extension for certain types of files was contagious--note the CONFIG.SYS (well in advance of MS-DOS).