Radstone PME 68-1B, Manual

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Short I/O Address Modifier Code
The 64k byte range is jumper selectable within the range $100000 to $FFFFFF, as de-
fined by jumper fields WH1, WH2, WH3 and WH4.
For valid decoding, jumper settings are:
OUT the corresponding address signal must be high (1).
IN the corresponding address signal must be low (0).
Table 23 lists the jumper positions, the corresponding address signals and the default
condition. Figure 40 illustrates the jumper circuit arrangement. The position of the short
I/O jumpers are shown on the location diagram Figure 39.
Figure 39 Location of Short I/O Jumpers
The binary code set on WH1-WH3 and WH2-WH4 is compared with the binary code of
address bits A16-A23 by the 74LS688. The AM4 signal is generated when A16-A23
matches the link setting. The settings therefore determine the two most significant HEX
digits for the start address of the I/O short address range. e.g. 2A0000 to 2AFFFF.
WH1
WH3
WH4
WH2
B
PME68-1B Manual
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