PDP8 / ETOS

[Johnny Billquist]

On 2015-10-19 13:03, Johnny Billquist wrote:
> On 2015-10-19 12:40, Rick Murphy wrote:
>> At 11:08 PM 10/18/2015, Johnny Billquist wrote:
>>> On 2015-10-19 04:58, ben wrote:
>>>> On 10/18/2015 8:43 PM, Johnny Billquist wrote:
>>>>> thus making it also able to run under MULTOS-8.
>>>>>
>>>>> Memory requirements and availability is a different story, but yes,
>>>>> ADVENT will require the full 32K, as far as I remember.
>>>>
>>>> I think a few changes where made a few years back, It could be a bit
>>>> smaller now with the latest code.
>>
>> Not significantly. Small enough to be much less likely to run out of
>> memory even with multiple 2-page handlers installed, but certainly not
>> small enough to allow it to run in 16K, for example.
>>
>> The loader map says:
>>   70000  = 1ST FREE LOCATION
>>
>> That means that it uses up all of 28K (with FRTS) without any device
>> drivers installed. If it was possible to bum another couple of pages it
>> might be possible to get it to work with 28K, but currently it won't.
>> 32K is required for it to work. As always with trying to make code more
>> compact, the more times you go back to try to shrink things the harder
>> it gets. I haven't tried for several years, however.
>
> Unless I remember wrong, the space for device drivers is already
> reserved in FRTS...?
> Device handlers always sits in field 0. Thus, they cannot really be
> loaded dynamically, and certainly not beyond the top of the program.

(And to clarify myself, by dynamically I mean that you could just 
allocate random memory somewhere, and load a device driver in there. 
They have to be in field 0, and you need to more carefully manage memory 
in field 0 for that, and other reasons.)

By the way, could you describe how you managed to squeeze some memory 
from ADVENT? And if the first free location is 70000, then it sounds 
like it would be possible to run in 28K.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol