Search found 331 matches

by RMartins
Thu May 10, 2018 10:24 pm
Forum: Announcements
Topic: April 23rd Spectrum Computing Competition Poll
Replies: 22
Views: 1225

Re: April 23rd Spectrum Computing Competition Poll

I heard his arcade cabinet project went wrong and became Missus on the jacuzzi cabinet The Arcade is fine and working :D But I have not played with it for a while now. I need to do some maintenance on it. I have a new board to swap in, a new starter for the markee light,, 2 fans to replace, and eve...
by RMartins
Thu May 10, 2018 6:52 pm
Forum: Announcements
Topic: April 23rd Spectrum Computing Competition Poll
Replies: 22
Views: 1225

Re: April 23rd Spectrum Computing Competition Poll

Unfortunately, I have been under water Is that a predictive text error, a colloquial phrase or have you been literally been on a submersible? It's a loose direct translation of a Portuguese expression, that means, "having too much work to do in very little time, without time to do anything else".
by RMartins
Thu May 10, 2018 6:21 pm
Forum: Announcements
Topic: April 23rd Spectrum Computing Competition Poll
Replies: 22
Views: 1225

Re: April 23rd Spectrum Computing Competition Poll

Attempting to use a computer while scuba diving can be dangerous! Actually it's quite the opposite :lol: I do Scuba Dive since 2000 (when I have free time), I have in excess of 100 dives, in several parts of the world, I do use a depth computer (or two, a depth gauge and a compass), to control my a...
by RMartins
Thu May 10, 2018 1:07 pm
Forum: Announcements
Topic: April 23rd Spectrum Computing Competition Poll
Replies: 22
Views: 1225

Re: April 23rd Spectrum Computing Competition Poll

Unfortunately, I have been under water, for the last weeks, and had no time to try them.
by RMartins
Wed May 09, 2018 1:23 pm
Forum: Programming
Topic: What was the SLL instruction supposed to do?
Replies: 20
Views: 761

Re: What was the SLL instruction supposed to do?

A CPU is basically a state machine, that given a set of inputs generates some output and changes internal state. When the documented instructions, do not cover all possible combinations, the curious human mind, will need to find out, what happens in the other cases :) And the search for undocumented...
by RMartins
Wed May 09, 2018 9:52 am
Forum: Programming
Topic: What was the SLL instruction supposed to do?
Replies: 20
Views: 761

Re: What was the SLL instruction supposed to do?

... And here's the July 1981 article that it refers to, which instead of SLL, uses the bizarre notation DUPINC. How about incorporating that into modern assemblers? :lol: Note the Editors note on that page: These OpCodes are not tested during production of the Z80 chip by Zilog. It is possible, in ...
by RMartins
Wed May 09, 2018 9:31 am
Forum: Programming
Topic: What was the SLL instruction supposed to do?
Replies: 20
Views: 761

Re: What was the SLL instruction supposed to do?

I read in a book somewhere, don't remember exactly where, that the first Z80 chips that were commercially available, didn't have a reliable SLL, and hence the reason, for Z80 not to document it.

How true this is, is up for grabs.
by RMartins
Tue May 08, 2018 8:33 pm
Forum: Programming
Topic: What was the SLL instruction supposed to do?
Replies: 20
Views: 761

Re: What was the SLL instruction supposed to do?

This document, documents it, and I was apparently wrong :)

http://www.z80.info/zip/z80-documented.pdf
by RMartins
Tue May 08, 2018 8:17 pm
Forum: Programming
Topic: What was the SLL instruction supposed to do?
Replies: 20
Views: 761

Re: What was the SLL instruction supposed to do?

I might be stretching my memory here, and going against what is stated in the Z80 manual (old one had lots of errors, around 20, or the new one, from 2016), but: - SLA stands for Shift Left Arithmetic, which means that it should preserve the Sign bit, but the manual states it differently. - SLL stan...
by RMartins
Mon May 07, 2018 1:22 pm
Forum: Graphics
Topic: Put Here Graphics That Have Nowhere Else To Go
Replies: 83
Views: 3953

Re: Put Here Graphics That Have Nowhere Else To Go

So what is concerning you guys, is that the guy doesn't have a mustache, but an incomplete 2 days beard, that look s like a mustache :)

OK, I'll se what I can do, probably with dithering.