Reply 180 of 3179, by hard1k
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wrote:This what I understand from what hard1k said and gus pnp pro card config: Gus pnp pro can only handle 8mb because 2 banks are re […]
This what I understand from what hard1k said and gus pnp pro card config:
Gus pnp pro can only handle 8mb because 2 banks are reserve for 512kb for Gf1 compatibility and the other 2 control the rest.
Am I correct?
But If you make total use of 16mb it will use all 4 banks. So there is no need for soj. GUS will only adress up to A19. I don't think there is the need for jumpers, since it has the adress limitation.
Is this correct?
First, you're almost right about the GUS PnP Pro. The 4 BKSEL lines are distributed in the following way:
0 and 1 go to SOJ if it's enabled by JP8, otherwise they go to SIMM 1 and 2,
2 and 3 to SIMM 1 and 2 if the SOJ is enabled by JP8, otherwise they go nowhere (or to SIMM 3 and 4 in case of a modded GUS with additional 2 SIMMs on the back for up to 16Mb support).
Second, you're right about no need for a SOJ - if we put a SIMM72 socket on the board, it will occupy all 4 banks, and additional bank switching between an onboard SOJ and a half of the installed SIMM doesn't sound reasonable.
As far as the address limitations are concerned, InterWave doesn't make any difference for installed RAM, it doesn't even know its physical package - whether it's a SOJ, SIMM or anything else. It treats all 4 banks equally, making the first 1Mb available for software seeking for an original GF1, and making all installed RAM (including the first 1Mb) available for any software (including its Win9x driver itself) looking for an InterWave in its native mode.
Thus no distinction for installed RAM shall be made despite its size and physical implementation - the chip will see and use it as I described above.
But as there is a possibility for some incompatibility with 16Mb, jumpers might be useful for a user to limit the installed RAM without having to replace the SIMM.
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