understanding Memory-extension

[Matthias Barthel]

i need help for understanding how i work with a installed memory extension on the pidp1.

The posiible address in the addresspart of the 18 bit word is 7777, how can i address a memory-location in bank 1 ? Do i always a indirect jump to the other banks ?

That would be my approach...

jmp -i foo

foo, 10100

when this is right i must do any opcode indirect while extend mode is active?

BTW...can macro1 handle the memory extension ?

many thanks!

Matthias

[Bill E]

Using extended memory is a bit inconvenient. You first enable it via the eem command.

Then ALL indirect references are full 16-bit addresses. You can only reference data in other banks via

an indirection. Once you jump to an address in another bank, that bank becomes the current bank and all

regular 12-bit non-indirect access is to that bank.

There are other considerations if you are using interrupts, this is documented in the pdp-1 handbook.

Note that neither macro nor macro1 will handle extended memory, you can't load code or data into any bank other than 0.

Am1 does handle that quite nicely. :)

Bill

[Matthias Barthel]

Thanks Bill,

I take a look at your AM1 to create a Testprogram wich loads data into a extended memory location. I implemented a Type15 Memory Extension to my Eps32-Simulator and  i want to test the new Feature if it works correct. 

I imagine that the regular rimloader loads a program into bank0 , the program starts extend-mode with eem and reads the data from the papertape to the extend-memory-banks. 

Matthias 

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[Unibus]

Hi,

Just out of curiosity... Was there any difference between the Type 15 Memory Control which could support 16 of the Type 12 Memory (4,096 words) and later Type 121 Memory Controls supporting the Type 170 Memory (16,384 words). Functionally to me they look the same.

Regards,

Garry

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[Bill E]

Yes, AM1 'punches' a loader before the program, the same as macro and macro1 do. However, it's a different loader that handles extended memory loading. It resides at 7751, same as the usual bin loader.

AM1 allows a program to have code in any of the memory banks, controlled by a 'bank n' directive in the source. The loader will then put the code in the correct banks.

Bill

[Matthias Barthel]

I'm curious if your rimloader works with my esp32 simulator. In my simulator, I have installed the readin mode as faithfully as possible. 

A special readin mode reads the rimloader from the tape and then the rimloader is started by the CPU and reads the rest of the tape into the memory and starts the program at the end .

Matthias 

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[Bill E]

My extended memory bin loader is in rim format, so an AM1 produced binary loads via readin as usual. When my bin loader starts, it does enable extended memory via the eem instruction. Otherwise, it is similar to the existing bin loader, but not compatible with that format since it has to deal with extended addresses.

Here  it is. Note no checksum, we're not reading from electromechanical devices, no need for checksums.

lai=760040

7751/
    eem
loop, rpb
    lai
    and (177777
    dac addr
    spi
    jmp i addr /done
    rpb
    dio end
load, rpb
    dio i addr
    idx addr
    sas end
    jmp load
    jmp loop
addr, 0
end, 0
constants
start 7751

Bill

[Matthias Barthel]

Many thanks 👍 

Is it possible to build only the AM1 crossassembler from your git ?

Matthias 

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[Bill E]

Yes. Easiest way is to get the entire project via zip, unzip it. Then go to the Tools/AM1 directory and just type 'make'.

If you want to use the include files I've already defined, they are in the Am1Includes dir. You will find other useful tools in the Tools dir also.

Documentation is in the Docs directory.

Bill