[Simh] MAME and simh

[Wilm Boerhout]

Johnny Billquist schreef op 3-7-2020 om 13:24:
> On 2020-07-03 13:19, Johnny Billquist wrote:
>> On 2020-07-03 13:14, Lars Brinkhoff wrote:
>>> Johnny Billquist wrote:
>>>> I am not at all sure I agree with that... I think you too should look
>>>> at the VT100 technical manual and see how soft scrolling is done, as
>>>> an example of a place where the hardware emulation can actually become
>>>> rather tricky...
>>>
>>> Now I'm curious.  If you have a title and a page number, I will take a
>>> look.
>>
>> I posted this last night, but here it comes again:
>>
>> You really should check out of smooth scrolling on the VT100 is 
>> accomplished... 
>> (http://www.bitsavers.org/pdf/dec/terminal/vt100/EK-VT100-TM-003_VT100_Technical_Manual_Jul82.pdf, 
>> page 4-97, section 4.7.9 - "Split Screen Smooth Scrolling". Emulating 
>> those hardware tricks are not going to be easy...
>
> Oh, and just for the people who don't want to read a lot of 
> documentation, the smooth scrolling is essentially done by the 
> terminal by changing where the source of the video signal generation 
> picks up font information, so that you actually start scanning at a 
> specific line of the font definition for characters at the video 
> generation stage. And then you do additional trickery so that you 
> start scanning the next line data as well, so that compared to the 
> line above, this line is generated using data from two lines, and your 
> picking up font definition lines with offsets, and then you need a bit 
> of special casing for the first and last lines of the region.
>
> I hope that made sense... :-)
>
>   Johnny
>
The plain English description of "how it works" in the manual should be 
used in every advanced programming class.

"Now, class, program this in SNOBOL or your own favorite programming 
language." :-)

/Wilm