Memory manipulation commands The memory manipulation commands are useful for debugging software and hardware. A safe memory area for experimenting with these commands is the $8100-$10000 memory range. Between the inbuilt monitor, the inbuilt editor, and theraw disk syscall s, youcan dofromthekeyboard nearlyeverythingtheMS-DOS versionof Norton’sUtilities can do,without even firingupa disk drive. I’llexplain more on using these in the Assembler Manual , since they are a bit heavy for a beginner. Examining memory MDB [a1] [a2] MDW [a1] [a2] MDL [a1] [a2] Mnemonic: Memory Dump (Byte, Word or Long) These are the memory dump commands.
MDB dumps memory in byte format, MDW in word format, MDL in long format. All dump formats display the data in ASCII form on the right hand side. With no arguments the dump commands display 64 bytes of memory,starting from the address at which the previous dump finished. If the argument is entered then the 64 bytes of memory at this address are displayed. If the ‘a1’ and ‘a2’ arguments are entered then all of the memory between these addresses is displayed. Long memory dumps may be halted using . Alt C Continuous memory examination MRDB a1 MRDW a1 MRDL a1 Mnemonic: Memory Repetitively Display (Byte, Word, Long) Thesecommandscontinuouslydisplaythevalueofthebyte,wordorlongataddress a1.
This function is useful for examining addresses which are being changed by interrupt routines, but it is mainly for monitoring I/O addresses during hardware debugging and development. The terminates memory examination. Alt C 1616/OS Commands User Tutorial Manual Page 77