 |
전자부품 데이터시트 검색엔진 |
|
|
전자부품 데이터시트 검색엔진 |
|
Z80 데이터시트(PDF) 51 Page - Zilog, Inc. |
|
|
|||||||||||||||||||||||||||||
Z80 데이터시트(HTML) 51 Page - Zilog, Inc. |
|
|
51 / 330 page  < %27 2GTKRJGTCNU 7UGT /CPWCN UM008101-0601 Direct Memory Access Direct Memory Access DMA OVERVIEW Direct Memory Access (DMA) and DMA Controllers are dedicated to controlling high-speed block transfers of data independently of the CPU. DMA data transfers are usually between memory and I/O, or vice versa. A DMA controller (DMAC) also performs some transfers that have tradi- tionally been done by the CPU. For example, the Z80 DMA can perform memory-to-memory, memory-to-I/O, and I/O-to-memory transfers, as well as search for particular patterns of bits in a byte either simulta- neously with or independently of transfers. The advantages of DMA transfers are: • Transfers bypass the CPU • Transfers are fast CPU Data Transfers In systems without DMA, data transfers must pass through the CPU and be implemented in software. Data transfers through the CPU include executing an instruction sequence for input and output, and tracking each byte of data in the block to be transferred. Figure 15 illustrates the minimum sequence of instructions that must be fetched from memory and executed by conventional CPUs to transfer a block of data one byte at a time. Most CPUs require many more instructions. CPU transfers are relatively slow and tie up the CPU. In addition response time (startup time for the first byte) is also usually slow because the I/O device typically uses interrupts to signal its readiness, and the CPU interrupt service routine causes a significant time lag in transferring the first byte. |
|
링크 URL |
| ALLDATASHEET 가 귀하에 도움이 되셨나요? [ DONATE ] |
Alldatasheet는? | 광고문의 | 운영자에게 연락하기 | 개인정보취급방침 | 링크 투 데이터시트 | 링크교환 | 제조사별 검색 All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Korean ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
