Screen 4 - vram usage

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By pizzapower

Master (132)

pizzapower's picture

30-11-2022, 01:48

gdx wrote:

The "concept of page" is a false good idea to explain the operation of the VDP because it suggests that everything displayed on the screen is in the selected page when is not the case.

What? What about SET PAGE? That's baked into BASIC, you know.

Quote:

This confuses beginners. You need to have a general knowledge of VDP to understand this "concept". By directly explaining what is (VDP uses tables), it gives a more solid base, more quickly.

I suppose you think a page is just a high level concept expressed as a numeric value, which is a very literal and limiting point of view, since the MSX standard has been using pages since the very beginning (every slot has four 16k pages for instance). If you think that the concept of page is a bad idea maybe you should remove it from the wiki then. Mentioning them partially with no further explanations does no one any favours. I don't care either way since I don't use the wiki.

By gdx

Enlighted (5994)

gdx's picture

30-11-2022, 08:08

pizzapower wrote:

What? What about SET PAGE? That's baked into BASIC, you know.

The fact that you ask this question shows that you have not understood at all what I am talking about. Basic's SET PAGE uses this concept precisely to simplify. And it is precisely those who are accustomed to Basic who have the most difficulty handling the VDP in assembler because these are tables that must be handled, not peusdo-pages.

pizzapower wrote:

If you think that the concept of page is a bad idea maybe you should remove it from the wiki then.

We are talking about VDP here, aren't we? I'm not talking about memory pages in which we can select memory segments via a mapper or slots. The VDP has no mapper or slot.

PS: Also note that the wiki is made by several people who each have their own vision and experience. The goal is not to reproduce existing documentations but to centralize the information and that everyone adds their experiences. You can keep your blinders on and deprive yourself of that. I totally don't care.
Since the wiki exists there is more software that works correctly on all the different MSX because the hardware is better known. You deprive yourself of that, that's all.

By ro

Scribe (4863)

ro's picture

30-11-2022, 08:53

The thing is, every term is a semantic concept. At some point one or more person decided on the word "Page" being used to display a portion of video-RAM to the display. The VDP takes care of that. Using the term "name table" is another concept. Such concepts are usually a functional / practical approach to describe the outcome of a technical concept.

As an asm coder myself, I too use the (V)Page term to set the right portion of data to display. In abstract, I call my subrout VPAGE with A=0-3 and transform that to the right register data needed to change the current displaying piece of video-RAM.

I re-use this MSX-BASIC term because it is a functional short description that we all know. Nothing more, nothing less. It gets the job done.

So, which idea should we discuss next?

By PingPong

Prophet (4086)

PingPong's picture

30-11-2022, 12:40

ro wrote:

As an asm coder myself, I too use the (V)Page term to set the right portion of data to display. In abstract, I call my subrout VPAGE with A=0-3 and transform that to the right register data needed to change the current displaying piece of video-RAM.

Exactly! you implemented a page concept at your sw level doing what effectively should be done by the VDP is it has natively a similar concept.
The fact that you have a piece of code that output the pageaddress from a page number, proves that vdp itself does not have a page concept.
It's only a coder abstraction

By PingPong

Prophet (4086)

PingPong's picture

30-11-2022, 12:44

[quote=gdx wrote:
pizzapower wrote:

What? What about SET PAGE? That's baked into BASIC, you know.

The fact that you ask this question shows that you have not understood at all what I am talking about. Basic's SET PAGE uses this concept precisely to simplify. And it is precisely those who are accustomed to Basic who have the most difficulty handling the VDP in assembler because these are tables that must be handled, not peusdo-pages.

It's incredible how this guy keeps to not see the evidence. ;-) The page concept, (the abstraction) sits on MSX BASIC not the VDP itself.

By pizzapower

Master (132)

pizzapower's picture

30-11-2022, 14:08

gdx wrote:
pizzapower wrote:

What? What about SET PAGE? That's baked into BASIC, you know.

The fact that you ask this question shows that you have not understood at all what I am talking about.

Yeah, on that I agree. I have no clue what you are talking about because VDPs are not simple. If one wants to access VDP directly and use it to its full extent with assembly, one should learn all the required concepts, including memory pages, timing issues and whatnot. That doesn't mean we shouldn't write lots of introductions to help them get there, but I don't think you should remove things that require a "general knowledge of VDP" (or you changed your mind and it is useless now?) from technical and descriptive docs just to appease a certain type of reader.

pizzapower wrote:

We are talking about VDP here, aren't we? I'm not talking about memory pages in which we can select memory segments via a mapper or slots. The VDP has no mapper or slot.

That's just how you select it, not how you think about them or use them after selecting them. Same goes for the VDP. Besides, the concept of a currently visible page separated from all the other invisible ones cannot simply be abstracted away. 😁

Quote:

You can keep your blinders on and deprive yourself of that. I totally don't care.

That's incredibly rude. I said I don't care about the wiki so as not to sound inconsistent with my current position, but it looks like I stepped on someone's toes. So, yeah, YOU DO CARE. Or you wouldn't be so rude as to compare people to animals. I think the moderators should know about your rudeness.

And maybe you should consider that people don't use the wiki if they already have great docs on their native language by some passionate Brazilian enthusiasts. It hasn't even crossed my mind to use the wiki considering all the great choices I have available to me. 🤷

By Sandy Brand

Champion (295)

Sandy Brand's picture

30-11-2022, 17:51

Yes I agree. The tone of these discussions have been rather hostile which is not conducive for good conversations at all.

People need to realize that they are posting on a retro computer forum, where, in all likeliness, their peers will also have over 30 or 40+ years of software engineering experience. So to just blatantly state that they don't know what 'abstraction' means or that they are not able to understand certain basic software/hardware concepts, is quite frankly really bad debating style.

By PingPong

Prophet (4086)

PingPong's picture

30-11-2022, 20:05

Quote:

I think the moderators should know about your rudeness.

So, give us lessons ,of your education. But before, take some time to review your previous posts. :-)
no people here that joined to this discussion can say to the other about being rude.

By Metalion

Paragon (1616)

Metalion's picture

30-11-2022, 20:48

Personnally, I am stunned (to say the least) at the utter and complete absence of moderation on this thread ! This stupid and useless semantic war has been going on for almost 2 weeks now, and absolutely no one did something to stop it.

By thegeps

Paragon (1154)

thegeps's picture

01-12-2022, 00:36

Exactly! So, moderators, please turn page! (Ok, I'm joking, you know...)

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