发明名称 |
Selectable 8/16 bit DMA channels for ISA bus |
摘要 |
In a personal computing system the function of the DMA controllers in the "AT" or "ISA" bus has been modified so that the system may select whether the 16-bit DMA channels are to be used as 8-bit DMA channels or 16-bit DMA channels. An 8/16-bit mode bit for each of the 16-bit DMA channels is written in a control register during the system Power On Self Test routine. Once the mode bit is written for each of the three 16-bit DMA channels, it may be read when the channel is active to select whether the channel is to operate as an 8-bit or 16-bit channel. With this mode bit information available, the page addressing may be selectively changed from 128k size pages to 64k size pages when a 16-bit DMA channel is to be converted to 8-bit. In addition, the byte addressing within a page may be changed from two byte addressing during 16-bit mode to single byte addressing during 8-bit mode.
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申请公布号 |
US5465332(A) |
申请公布日期 |
1995.11.07 |
申请号 |
US19920947680 |
申请日期 |
1992.09.21 |
申请人 |
INTERNATIONAL BUSINESS MACHINES CORPORATION |
发明人 |
DELOYE, MICHAEL J.;FUOCO, DANIEL P.;MOELLER, DENNIS L. |
分类号 |
G06F13/28;(IPC1-7):G06F13/28;G06F13/00;H01J3/00 |
主分类号 |
G06F13/28 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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