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Pascal on the 99/4A


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On 6/5/2024 at 4:12 PM, apersson850 said:

I've not managed to get the p-system to automatically find more than one disk controller in the system.

I can use it with the physical drives and two RAMdisks, but then I inject the PCB for the RAMdisks manually. To avoid changing TOPMEM I put them in the sprite attribute table, since I normally don't use that anyway.

With TIPI at >1000, it is able to automatically detect it as a drive controller when DSK1-DSK3 are set up. It does not *seem* detect the TI controller at >1100 in that situation. 

On 6/5/2024 at 4:12 PM, apersson850 said:

All disk units point to the same place, since they use the same controller. But the p-system knows that there will not be more than three disks, so it doesn't populate the entries for units #10, #11 and #12.

So for a CorComp controller which has four drives you simply copy the same value as is stored for #4 to the place where you have #10.

Since TIPI actually supports DSK4 and DSK5 as well, we should be able to get those working too by adding 2 more PCB's. It should be simpler than RAMDISKS because the DSR is unchanged. Do we know where the PCB's are located in VDP? I looked at the location pointed to by TOPMEM in Classic99 but did not recognize PCB's at first glance.

What I still don't understand however is why the Editor is running out of VDP memory with only 3 TIPI disk drives as it should theoretically be a similar situation to when a real TI controller is present with 3 drives attached. Any thoughts on this? The answer probably lies with inspection of the PCB table once I know where it is.

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Posted (edited)

The physical drives controlled by the same controller use the same PCB. The call just changes a parameter in the PCB to indicate which drive to use.

Since I don't have any TIPI I've not checked this, but perhaps the system by default allocates space for a PCB for the standard disk controller and does then allocate one more when it unexpectedly discovers a disk controller showing up before the standard one during the search?

Pure speculation - I don't know why this happens.

Edited by apersson850
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  • 2 weeks later...

I have a main program which uses a custom library of 3 separate units. The units USE several of the TI supplied units (speech, sound, random etc...) and compile just fine. However, unless I also USE these same TI supplied units in the main program which does not need them, I get the error UNIT NOT DECLARED IN PREVIOUS USES.

I don't understand why that is the case, and doing so robs precious memory from the main program...



Library TESTLIB has:

  • UNIT1
  • UNIT2

Both UNIT1 and UNIT2 need the TI supplied units SUPPORT and RANDOM which they explicitly USE in their INTERFACE section.

Now TEST is a program which USES the TESTLIB library, but does not need SUPPORT or RANDOM to work. However, it seems I still have to USE SUPPORT and RANDOM in the TEST main program regardless, which does not make sense. 


I must be missing some concept here...

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