Block-transfer instruction
- Block-transfer instruction
On the PDP-10, the BLT (Block Transfer) instruction copies words from memory to memory. The left half of the selected AC specifies the first source address. The right half of the AC specifies the first destination address. The effective address specifies the last destination address. Words are copied, one by one, from the source to the destination, until a word is stored in an address greater than or equal to the effective address of the BLT.
Caution: BLT clobbers the specified AC. Don't use the BLT AC in address calculation for the BLT; results will be random. If source and destination overlap, remember that BLT moves the lowest source word first. If the destination of the BLT includes the BLT AC, then the BLT AC better be the last destination address.
Programming examples
Save all the accumulators: MOVEM 17,SAVAC+17 MOVEI 17,SAVAC ;Source is 0, destination is SAVAC BLT 17,SAVAC+16
Restore all the accumulators: MOVSI 17,SAVAC ;Source is SAVAC, destination is 0 BLT 17,17
Zero 100 words starting at TABLE. SETZM TABLE MOVE AC, [TABLE,,TABLE+1] ;Source and destination overlap BLT AC,TABLE+77
Move 77 words from TABLE through TABLE+76 to TABLE+1 through TABLE+77. BLT can't be done here because the source and destination overlap. MOVE AC, [400076,,TABLE+76] POP AC,1(AC) ;Store TABLE+76 into TABLE+77, etc. JUMPL AC,.-1
ee also
* BitBLT
* Jargon File entry for:
** [http://www.catb.org/~esr/jargon/html/B/BLT.html BLT]
** [http://www.catb.org/~esr/jargon/html/B/blit.html blit]
** [http://www.catb.org/~esr/jargon/html/B/bitblt.html bitblit]
References
* [http://www.inwap.com/pdp10/hbaker/pdp-10/Full-Word.html MIT PDP-10 'info' file]
Wikimedia Foundation.
2010.
Look at other dictionaries:
Instruction cycle — An instruction cycle (sometimes called fetch and execute cycle, fetch decode execute cycle, or FDX) is the basic operation cycle of a computer. It is the process by which a computer retrieves a program instruction from its memory, determines what … Wikipedia
Basic block — In computing, a basic block is code that has one entry point (i.e., no code within it is the destination of a jump instruction), one exit point and no jump instructions contained within it. The start of a basic block may be jumped to from more… … Wikipedia
MOV (x86 instruction) — In the x86 assembly language, the MOV instruction is a mnemonic for the copying of data from one location to another. The x86 assembly language actually contains a number of different opcodes that perform a move. Depending on whether the… … Wikipedia
Bit blit — ( bitblt , blitting etc.) is a computer graphics operation in which several bitmap patterns are combined into one using a raster operator .OriginsThe name derives from the BitBLT machine instruction for the Xerox Alto computer, standing for Bit… … Wikipedia
BLT — The acronym BLT, when used alone, may refer to one of the following:*BLT sandwich (bacon, lettuce, and tomato) *BitBLT Short for Bit Block Transfer an operation in computer graphics. BLT is sometimes expanded to blit . *Block transfer instruction … Wikipedia
BLT — abbr. BLock Transfer comp. abbr. Baghdad Local Time (+3:00) acronym Bacon, Lettuce, and Tomato (sandwich) acronym BLock Transfer (Instruction) acronym Branch Less Than (Instruction) … United dictionary of abbreviations and acronyms
CDC 6600 — The CDC 6600 was a mainframe computer from Control Data Corporation, first delivered in 1964. It is generally considered to be the first successful supercomputer, outperforming its fastest predecessor, IBM 7030 Stretch, by about three times. It… … Wikipedia
Zilog Z80 — One of the first Z80 microprocessors manufactured; the date stamp is from June 1976. Produced 1976 Common manufacturer(s) Zilog … Wikipedia
Higher education in Nova Scotia — (also referred to as post secondary education) refers to education provided by higher education institutions in the Canadian province of Nova Scotia. In Canada, education is the responsibility of the provinces and there is no Canadian federal… … Wikipedia
Microcode — is a layer of hardware level instructions and/or data structures involved in the implementation of higher level machine code instructions in many computers and other processors; it resides in special high speed memory and translates machine… … Wikipedia
