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Using a 1M RAM card in 48GX slot 1
12-23-2019, 10:47 PM
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Using a 1M RAM card in 48GX slot 1
Calling all 48 GX hardware experts...

Background: The 48 GX can access all the memory in an HP 1 Meg RAM card in slot 2, because the GX's slot 2 has special pins which are dedicated to bank switching those RAM cards. The same pins in slot 1 are used for display output, for use with the old overhead projector LCD panel. That, of course, is why the LCD panel can only be plugged into slot 1 of a GX, and why HP 1M RAM cards are only supposed to be plugged into slot 2. (The 48 SX used those pins in both slots for display output).

Question: Can strategic use of the display on a 48 GX allow the banks of an HP 1M RAM card to be accessed when it's plugged into slot 1? In other words, can the bank-switching signals of slot 2 be faked by strategic display manipulation when the card is in slot 1?

Please note, I'm only talking about the large-capacity RAM cards which were designed for slot 2 of the 48 GX, which created multiple "ports" when plugged into slot 2. I'm not talking about the older multi-bank RAM cards which were designed for the 48 SX and which could only access one bank of 128K at a time, using special bank-switching software which you had to install.

Also, yes I know that plugging a large-capacity GX RAM card into slot 1 is a Bad Idea. I'm just wondering whether it's *possible* to access its banks by bit-twiddling the display.

Thanks in advance for any insights!

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Using a 1M RAM card in 48GX slot 1 - Joe Horn - 12-23-2019 10:47 PM

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