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INTRODUCTION
The next higher order address lines, A8 through A 15, are present throughout the machine cycle on both the 8088 and the 8085A. Note that the 8088 has four other address lines, AI6 through AI9 not present on the 8085A and which the 8088 time- multiplexes with status information during the machine cycle.
The three control lines RD, WR, and 101M signal the actual data transfer during a machine cycle, whether the 8088 is reading or writing, and whether that transfer is taking place with respect to 110 devices or memory
devices. Also, the 8088, like the 8085A, has other lines containing cycle status infor- mation available at the beginning of the machine cycle to inform other devices in the system what type of machine cycle is being performed.
There are several other control lines used with the 8088 such as interrupts, HOLD, READY. See Chapter 3 for details.
Using Special Multiplexed Bus Parts
Because the 8088 is so much like the 8085A, you may connect the 8088 directly to a whole family of multiplexed bus components de-
ADO- | < | > |
AD7 | ||
AS- | ||
| ||
| .A |
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ALE | ; |
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| |
8088 | ; | 8085A |
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| |
| ~ |
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101M |
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|
| ~ |
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DT/R |
| S1 |
STATUS | .A |
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550 1 |
| SO |
'I |
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SOSSIS AN EASY UPGRADE FOR EXISTING