Search found 11 matches

by Mills
Sun 25 Nov, 2018 9:51 am
Forum: Development
Topic: VGA VRAM Wrap
Replies: 2
Views: 934

Re: VGA VRAM Wrap

Well the code was tested it on a real VGA, and PCem is working OK. So that's not a bug, it just does not wrap around 64 KB but 256 Kb.
by Mills
Sat 24 Nov, 2018 5:44 pm
Forum: Development
Topic: VGA VRAM Wrap
Replies: 2
Views: 934

VGA VRAM Wrap

Hi, Thanks again for this great emulator. I think the VGA VRAM is not wrapping correctly on mode 13, (the one with only 64 Kb). Well, it wraps, but It always thinks the vram is 256 Kb (mode X) and I have to scroll 4 pages down until it reaches address 0 of VRAM again. Here you see a screenshot from ...
by Mills
Sun 02 Sep, 2018 8:43 am
Forum: Development
Topic: VGA Pixel panning registers
Replies: 6
Views: 1482

Re: VGA Pixel panning registers

Thanks! :D
by Mills
Wed 29 Aug, 2018 7:45 pm
Forum: Development
Topic: VGA Pixel panning registers
Replies: 6
Views: 1482

VGA Pixel panning registers

Hi everybody!. Testing some turbo C programs on PCEM, I discovered everything works great. But I think I found a "bug" in the VGA emulation, so I'll post my tests here. I made a simple program to scroll the screen using VGA hardware registers, based on this: ega-and-vga-smooth-scrolling-and-panning ...
by Mills
Thu 07 Dec, 2017 2:54 pm
Forum: General
Topic: 8086 emulation
Replies: 31
Views: 4770

Re: 8086 emulation

Thanks ruben_balea and SarahWalker, It now runs really well :). I have the "ZIVpackED by Eric ZMIRO 1991" copy, so everything ok. TITUS in CGA mode runs JUST as I remember on my 8086/8 using the Amstrad 3086 config. Maybe it's something to do with the emulation, or maybe the EGA and VGA really speed...
by Mills
Wed 04 Oct, 2017 10:19 am
Forum: General
Topic: 8086 emulation
Replies: 31
Views: 4770

Re: 8086 emulation

Well it's true a lot of abandonware sites make money with that games, and the games are sometimes bad copies that don't work well on original hardware. For example I had a bad lemmings copy, probably from an abandonware site I don't remember now. I had many of these games in floppies back in the day...
by Mills
Tue 03 Oct, 2017 7:16 pm
Forum: General
Topic: 8086 emulation
Replies: 31
Views: 4770

Re: 8086 emulation

Regarding "Titus the Fox": I tested a cracked copy of the game and: - Works fine on a 286 and higher - Crashes (black screen) after executing the COM file on any 8088 and 8086 All the manuals and web pages I read state that the game runs on a IBM PC or XT, so my conclusion is that the might be a bu...
by Mills
Tue 03 Oct, 2017 10:16 am
Forum: General
Topic: 8086 emulation
Replies: 31
Views: 4770

Re: 8086 emulation

I've made some tests with Generic XT clone and IBM XT (both have 8088 CPU) with VGA video adapter and MS-DOS 6.22. Norton Commander -> OK version 4 and therefore all versions up to 4 should work also, version 5 already requires a 286 or higher. Lemmings 1 -> OK, of course at 4.77 MHz takes more tim...
by Mills
Mon 02 Oct, 2017 10:23 pm
Forum: General
Topic: 8086 emulation
Replies: 31
Views: 4770

Re: 8086 emulation

Programs not working in 8088 emulation: -norton commander -lemmings1 -titus the fox When running them, the pc just stays forever in a black screen. I'm sure that it is a native 8088/86 behavior due to the lack of CPU instructions needed by complex programs created much later than a PC XT. Replacing...
by Mills
Sat 30 Sep, 2017 10:38 am
Forum: General
Topic: 8086 emulation
Replies: 31
Views: 4770

Re: 8086 emulation

8086/8088 can only access 1MB or memory, to use HIMEM.SYS you need at least a 286 with enough memory, on some chipsets even with only 1 MB you'll get a small amount of extended memory, Almost any 8086 program should work perfectly on a 8088 because all IBM PC and XT models and most of their clones ...
by Mills
Fri 29 Sep, 2017 6:26 pm
Forum: General
Topic: 8086 emulation
Replies: 31
Views: 4770

8086 emulation

Hi, I'm new in PCem so I might be doing something wrong. I wanted to emulate a machine like this: 8086 8 Mhz 640 kb ram VGA (I really wanted to emulate PS/2 Model 30 8086 with MCGA, But it is OK with the VGA). Some of the predefined machines show a 8086 cpu type, like Amstrad PC1512 for example. But...