Search found 37 matches
- Sun 27 Mar, 2022 10:06 am
- Forum: General
- Topic: Weird A20-related behaviour (bug?)
- Replies: 11
- Views: 1924
Re: Weird A20-related behaviour (bug?)
So how would it know to look for [8] in the data segement, e.g. (0:8), and [108] in the extra segment, e.g. fff0:108, in your original program? I'm not sure if I understand your question correctly. But in the reference "word ptr[8]" it's assumed that DS:8 is meant. DS is the default, per ...
- Sat 26 Mar, 2022 10:01 am
- Forum: General
- Topic: Weird A20-related behaviour (bug?)
- Replies: 11
- Views: 1924
Re: Weird A20-related behaviour (bug?)
I think disabling A20 at the beginning of the program and then enabling it shortly afterwards might be related to the LOADFIX issue. Supposedly, there are a very small number of programs that "play games" with memory address mathematics and rely/depend on the "wraparound" that h...
- Fri 25 Mar, 2022 9:39 am
- Forum: General
- Topic: Weird A20-related behaviour (bug?)
- Replies: 11
- Views: 1924
Re: Weird A20-related behaviour (bug?)
I did a more elaborate test, and I think I'm beginning to understand what happens. It seems that when the setting "DOS=HIGH" is present, DOS does some arcane deep wizardry behind the scenes. It seems that when running a program from the command line (or maybe from int 21h function 4Bh) DOS...
- Fri 25 Mar, 2022 8:11 am
- Forum: General
- Topic: Weird A20-related behaviour (bug?)
- Replies: 11
- Views: 1924
Re: Weird A20-related behaviour (bug?)
Here's a code snippet/subroutine i use in a "real" program to test whether or not A20 is enabled. This particular code requires a 386 CPU, but could be easily modified to work on a 286 (change the CMPSD to CMPSW, and change the CX counter value for the CMPSW). This code also doesn't poten...
- Thu 24 Mar, 2022 3:52 pm
- Forum: General
- Topic: Weird A20-related behaviour (bug?)
- Replies: 11
- Views: 1924
- Thu 24 Mar, 2022 10:49 am
- Forum: General
- Topic: Weird A20-related behaviour (bug?)
- Replies: 11
- Views: 1924
Weird A20-related behaviour (bug?)
So, I was trying to experiment with the "DOS=HIGH" setting in Dos, and I encountered some weird behaviour that's bugging me. Or it could be entirely logical, and it might only seem weird due to my ignorance. Basically, I set up a PCem virtual machine, with IBM PC/AT BIOS, with 80286 CPU, w...
- Sun 06 Sep, 2020 11:57 am
- Forum: General
- Topic: PCem Permedia 2 emulation
- Replies: 4
- Views: 3466
Re: PCem Permedia 2 emulation
This is about bank registers, permedia 2 supports only 256 colors in 640x400 and in 640x480 resolutions, rest resolutions and colors depth works only in linear framebuffer. Maybe SarahWalker will know, has register documentation. She said in another thread that she had the necessary info about the ...
- Sat 25 Jul, 2020 8:11 am
- Forum: Development
- Topic: documentation rework
- Replies: 13
- Views: 8823
Re: documentation rework
The is no problem to include the MD5/SHA1 Well, we should wait to hear the opinion of the principial author on this. Because for some copyright purists even this could be considered an infringement. the thing is that there is not just ONE valid file. There are many versions of a same ROM and all sh...
- Fri 24 Jul, 2020 6:43 am
- Forum: General
- Topic: PCem USB support
- Replies: 15
- Views: 12698
Re: PCem USB support
What would the USB 'connect' to? A host port? If I'm reading properly what the person who started this thread wrote, to emulated USB devices. Who will write the emulation code for these devices? Now this is the real question :) P.S. Another possibility is, of course, adding passthrough support for ...
- Tue 21 Jul, 2020 1:24 pm
- Forum: General
- Topic: Future graphics card emulation
- Replies: 112
- Views: 204986
- Tue 21 Jul, 2020 11:18 am
- Forum: General
- Topic: Future graphics card emulation
- Replies: 112
- Views: 204986
Re: Future graphics card emulation
> If the card you're thinking of isn't listed then it probably isn't interesting enough to be worth emulating. Forgive me for this (probably) stupid question, but is there any objective criteria for a card to be considered interesting/worthy? IMHO, the performance of the real thing shouldn't play a ...
- Thu 13 Feb, 2020 8:46 am
- Forum: General
- Topic: Request - Rendition Verite V1000
- Replies: 3
- Views: 4700
Re: Request - Rendition Verite V1000
It is possible to add this card in the next release of PCem? The Verite V1000? I'm wanting to emulate their video APIs - RRedline and Speedy3D - under Win95. Thanks :) Why would you want Verite support in PCem only to emulate Rendition APIs? IMHO, a PCem with Verite support would emulate a real PC ...
- Thu 28 Sep, 2017 8:08 am
- Forum: Development
- Topic: v13 feature freeze end of Friday 13th October
- Replies: 19
- Views: 18547
Re: v13 feature freeze end of Sunday 8th October
V13? This can't possibly be good... I'd suggest going straight to version 14...
But OTOH, it's amazing how far did PCem go since its early days... Congratulations and thanks!
But OTOH, it's amazing how far did PCem go since its early days... Congratulations and thanks!
- Mon 05 Jun, 2017 9:38 am
- Forum: General
- Topic: Expanded Memory Boards for 8088/8086 machines?
- Replies: 18
- Views: 16729
Re: Expanded Memory Boards for 8088/8086 machines?
Sadly, technical info about EMS boards seems very scarce...
- Mon 15 May, 2017 9:38 am
- Forum: General
- Topic: IBM PS/2 Model 55SX can't boot from ESDI hard disk
- Replies: 7
- Views: 7399
Re: IBM PS/2 Model 55SX can't boot from ESDI hard disk
The Wikipedia article on the PS/2 states that the Model 55SX has support for the ESDI controller while the Model 50 doesn't. The Model 50 has to rely on HDD controllers other than ESDI. IMHO, if Wikipedia says that, then it's wrong on this one. AFAIK, both model 50 and 55 (and 70) can support "...
- Mon 15 May, 2017 6:59 am
- Forum: General
- Topic: IBM PS/2 Model 55SX can't boot from ESDI hard disk
- Replies: 7
- Views: 7399
Re: IBM PS/2 Model 55SX can't boot from ESDI hard disk
> I bet that the inability to boot from the ESDI hard disk also affects the emulated IBM PS/2 Model 50 and IBM PS/2 Model 80 as well, but those machines have not been tested at this time.
Note that the ESDI controller in model 80 is very different and incompatible with that in models 50 and 55.
Note that the ESDI controller in model 80 is very different and incompatible with that in models 50 and 55.
- Fri 12 May, 2017 7:04 am
- Forum: General
- Topic: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
- Replies: 37
- Views: 26586
Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
Yes, OS/2 ver. 1.x uses 286 protected mode, as well as Microport System V/AT Unix, some versions of Xenix and even Minix, and others. But installing and using Windows 3.x is just easierBattler wrote:Doesn't early OS/2 use 286 protected mode? That would make it a good candidate for testing.
- Fri 12 May, 2017 6:58 am
- Forum: General
- Topic: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
- Replies: 37
- Views: 26586
Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
I'm not aware of any games that use protected mode on a 286 - it doesn't really gain you much over real mode other than a larger address space (but still with 64kb segments), and if you need that then it's probably easier just to use EMS/XMS rather than write a DOS extender. By that logic, Windows ...
- Fri 12 May, 2017 6:55 am
- Forum: General
- Topic: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
- Replies: 37
- Views: 26586
Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
Do you know any game that uses the 286 protected mode? Any game for Windows 3.1, for example (only joking, lol). Wolfenstein 3D maybe? Nope, it runs in real mode, AFAIK. Try "Syndicate" (1993) (I'm not actually sure, but there are indications that it might be built with a 286 extender)
- Thu 11 May, 2017 12:03 pm
- Forum: General
- Topic: Support for 5.25 fd-formatted floppy
- Replies: 8
- Views: 6622
Re: Support for 5.25 fd-formatted floppy
Fd-format was : " A DOS tool written in Pascal by Christoph H. Hochstätter that allows users to format floppy disks to a higher than usual density, enabling the user to store up to 300 kilobytes more data on a normal high density 3.5" floppy disk" (wikipedia). It is not related with ...
- Thu 11 May, 2017 11:35 am
- Forum: General
- Topic: Support for 5.25 fd-formatted floppy
- Replies: 8
- Views: 6622
Re: Support for 5.25 fd-formatted floppy
I don't think any real 5.25 inch HD floppies can reliably support 18 sectors (512 bytes each) per track. Unless they're modded to spin at less than the standard 360rpm, that is.
By the way, what's exactly the size of these images?
By the way, what's exactly the size of these images?
What exactly does this mean?altheos wrote:(1.6 version) floppies
- Thu 11 May, 2017 11:21 am
- Forum: General
- Topic: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
- Replies: 37
- Views: 26586
Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
Does Windows 3.0 run in real or protected mode? What happens when you run "win /r" and "win /s"? Did you check if HIMEM.SYS from Windows 3.0 works?ppgrainbow wrote: The Dell System 200 does work with Windows 3.0 and Windows 3.0a. I can only test this on PCem right now.
- Thu 11 May, 2017 7:07 am
- Forum: General
- Topic: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
- Replies: 37
- Views: 26586
Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR
Does it work with Windows 3.1? Does it work with any protected mode software at all? If not and it can't be repaired then really there is not much reason to keep it, IMHO.ppgrainbow wrote:The Dell System 200 does work with MS-DOS 3.31/MS-DOS 4.0x.
- Fri 21 Apr, 2017 8:21 am
- Forum: General
- Topic: Expanded Memory Boards for 8088/8086 machines?
- Replies: 18
- Views: 16729
Re: Expanded Memory Boards for 8088/8086 machines?
The 640k barrier is a convention, not a limit. The CPU can address up to 1 Mb, but DOS gets only the first 640 Kb (because memory above 0xA0000 is reserved). If the machine has an EGA or VGA-compatible videocard, then by definition, the region from 0xA0000 to 0xBFFFF is unavailable. You can place s...
- Wed 19 Apr, 2017 8:38 am
- Forum: General
- Topic: Expanded Memory Boards for 8088/8086 machines?
- Replies: 18
- Views: 16729
Re: Expanded Memory Boards for 8088/8086 machines?
Actually any 8088/8086 machine can't use more than 640k base memory. Are you sure? IMHO, SCP Gazelle could access 896Kb of RAM, and Altos 986 could access almost 1024K. Of course, neither of these machines was PC-compatible :) But, the idea about expanded memory boards seems good. Some DOS business...
- Sat 08 Apr, 2017 12:03 pm
- Forum: Development
- Topic: IBM PS/2
- Replies: 12
- Views: 11002
Re: IBM PS/2
Wow, thanks for supporting this little MCA machine, Sarah... Now, I can finally see how does this cryptic IBM ABIOS work under OS/2 1.3
- Sat 08 Apr, 2017 11:58 am
- Forum: Development
- Topic: IBM PS/2
- Replies: 12
- Views: 11002
Re: IBM PS/2
For those who want to test the model 50, you need to create the "i8550021" folder inside "roms" and there you'll need to place one or both of these files: 90x7423.zm14 90x7426.zm16 Thanks... but didn't the PS/2 model 50-021 come with a 20Mb MFM disk, connected to a MCA ST506/412...
- Thu 30 Mar, 2017 10:15 am
- Forum: Development
- Topic: IBM PS/2
- Replies: 12
- Views: 11002
IBM PS/2
I'm sorry if this question has been already asked; I couldn't find anything. So, would it be possible to emulate certain IBM PS/2 models for which ROM dumps are available? For example, Model 30 with 8086 or 80286. It would be interesting to play with the MCGA
- Thu 30 Mar, 2017 9:28 am
- Forum: General
- Topic: PC-DOS 1.10 and PCem v12
- Replies: 64
- Views: 44232
Re: PC-DOS 1.10 and PCem v12
What's surprising there? Formatting without /1 formats both sides, which obviously won't work with an inserted 180k image... It works fine on real hardware. Yet no (or at least almost no) real hardware behaves like these 160K/180K/320K floppy images. So the results you got with PCDOS2 were totally ...
- Sun 26 Mar, 2017 8:18 pm
- Forum: General
- Topic: [BUG] NSSI hangs AMI WinBIOS 486 machine!
- Replies: 40
- Views: 27649
Re: [BUG] NSSI hangs AMI WinBIOS 486 machine!
You people didn't understand my point, or I expressed myself in the wrong way. Of course all current PCem support IDE! What I meant was clone 286 and 386 (by clone I mean those motherboards you purchase alone so you can assemble a PC yourself) don't have an integrated/onboard IDE interface, you'll ...