; ED409.ASM ED409.ASM dated 1984 September ; This file is an overlay to EDFILE.COM which provides modifications. ; Since EDFILE is a particularly popular public domain program and ; since more fixes and modifications are sure to follow, this patch ; will be referred to by its date...4 for 1984 and 09 for September. ; This patch by Clint Lew ; South Bay Technical Support Group RCP/M (213) 970-9238 ; This patch corrects two small bugs in the current version. ; The first bug limited the size of the file to which direct jumps ; could be made. In the original version, for files greater than ; about 8000H, the "dump relative address" or "A" command would not ; consistently jump directly to all addresses. (Actually the address ; jump limit was dependent upon the file size). ; The second bug was a minor problem in that a jump to an address ; which happened to be on a sector boundary would send you to the ; block before the desired block. ORG 0528H PUSH H ;selected address LHLD 27C3H ;address offset CALL 2A3AH ;subtract offset from address LXI D,7 CALL 29DCH ;divide by 128 to get record number XCHG LHLD 27BCH ;LOF record number XCHG MOV A,D CMP H ;compare most significant byte JC 0357H ;selected record greater than LOF JNZ NEWREC ;less than LOF MOV A,E CMP L ;compare least significant byte JZ 0357H ;selected record equals LOF JC 0357H ;greater than LOF record NEWREC: SHLD 27CAH ;store valid record number JMP 0562H ;continue END ;************************************************************* ; General usage instructions for using ASM overlays ;************************************************************* ; I N S T R U C T I O N S ; ; ; First, edit this file to your preferences using any editor. ; Wordstar in non-document mode works very well for this. ; ; Second, assemble this file using Digital Research's CP/M ; assembler ASM.COM. For the file ED409.ASM, enter ASM ED409. ; ; Lastly, use DDT to overlay the results of this EDOVR program ; onto EDFILE.COM. The procedure for this overlay follows: ; ; A>DDT EDFILE.COM ; DDT VERS 2.2 ; NEXT PC ; 2C00 0100 (size varies with version) ; -IED409.HEX (note the "I" command) ; -R ("R" loads in the .HEX file) ; NEXT PC ; 2C80 0000 ; -G0 (return to CP/M) ; A>SAVE 44 EDFILE.COM (now have a modified .COM file) ; ; = = = = = = = = = = = = = = = = = =