Re: Help/info needed

From: André Fachat <afachat_at_gmx.de>
Date: Sun, 12 Jul 2026 03:17:58 +0200
Message-ID: <19f53e70970.2874.b4d1f2b66006003a6acd9b1a7b71c3b1_at_gmx.de>
Am 11. Juli 2026 18:01:46 schrieb silverdr_at_srebrnysen.com:

>> On 11 Jul 2026, at 15:32, groepaz <groepaz_at_gmx.net> wrote:
>>
>>>>> While it might be obvious, don't forget to open the file for (R)eading,
>>>>> or you may create it, even if absent :-)>
>>>> That's a good one. Then I have to make sure to find out how it is done in
>>>> assembly. I think it has to do with the second address but I'm sure I wil
>>>> find out.
>>> AFAIR it's done in assembly the same way as in BASIC – by ending the
>>> filename (before calling SETNAM) with appropriate ending (like `,S,R` for
>>> example (stays for SEQ,READ) the rest is done on the DOS side, whether from
>>> assembly or anything else.
>>>
>>> I vaguely remember those being described in the 1541 manual.
>>
>> the secondary address is different, too.... i forgot which is read and which
>> is write though :)
>
> I think this was 0 and 1 for LOAD and SAVE - at least that's in the 
> comments of my `sd_open_file.s`. Unsure now if it affects other types of 
> I/O. I _think_ everything else can use the remaining 2 to 14, whether for 
> reading or writing. But let's not strip Ruud of all the fun checking it 
> himself ;-)

Basically - from a logical point of view - secondary address 0 is shorthand 
for ,P,R and secondary address 1 is short for ,PW. (As I learned recently, 
save does some performance optimizations,  as it expects to get the whole 
contentin one go)

André
>
> --
> SD!
Received on 2026-07-12 03:00:36

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