Search found 25 matches

by vbdasc
Thu 28 Sep, 2017 8:08 am
Forum: Development
Topic: v13 feature freeze end of Friday 13th October
Replies: 19
Views: 2189

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!
by vbdasc
Mon 05 Jun, 2017 9:38 am
Forum: General
Topic: Expanded Memory Boards for 8088/8086 machines?
Replies: 18
Views: 1592

Re: Expanded Memory Boards for 8088/8086 machines?

Sadly, technical info about EMS boards seems very scarce...
by vbdasc
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: 580

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 "...
by vbdasc
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: 580

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.
by vbdasc
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: 34
Views: 1647

Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR

Battler wrote:Doesn't early OS/2 use 286 protected mode? That would make it a good candidate for testing.


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 easier :)
by vbdasc
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: 34
Views: 1647

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 ...
by vbdasc
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: 34
Views: 1647

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)
by vbdasc
Thu 11 May, 2017 12:03 pm
Forum: General
Topic: Support for 5.25 fd-formatted floppy
Replies: 8
Views: 632

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 ...
by vbdasc
Thu 11 May, 2017 11:35 am
Forum: General
Topic: Support for 5.25 fd-formatted floppy
Replies: 8
Views: 632

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?

altheos wrote:(1.6 version) floppies


What exactly does this mean?
by vbdasc
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: 34
Views: 1647

Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR

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.


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?
by vbdasc
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: 34
Views: 1647

Re: DELL System 200 (and others) HIMEM.SYS (MS-DOS 5.0+) GATE A20 ERROR

ppgrainbow wrote:The Dell System 200 does work with MS-DOS 3.31/MS-DOS 4.0x.


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.
by vbdasc
Fri 21 Apr, 2017 8:21 am
Forum: General
Topic: Expanded Memory Boards for 8088/8086 machines?
Replies: 18
Views: 1592

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...
by vbdasc
Wed 19 Apr, 2017 8:38 am
Forum: General
Topic: Expanded Memory Boards for 8088/8086 machines?
Replies: 18
Views: 1592

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...
by vbdasc
Sat 08 Apr, 2017 12:03 pm
Forum: Development
Topic: IBM PS/2
Replies: 12
Views: 1252

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 :)
by vbdasc
Sat 08 Apr, 2017 11:58 am
Forum: Development
Topic: IBM PS/2
Replies: 12
Views: 1252

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...
by vbdasc
Thu 30 Mar, 2017 10:15 am
Forum: Development
Topic: IBM PS/2
Replies: 12
Views: 1252

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 :)
by vbdasc
Thu 30 Mar, 2017 9:28 am
Forum: General
Topic: PC-DOS 1.10 and PCem v12
Replies: 64
Views: 5032

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 ...
by vbdasc
Sun 26 Mar, 2017 8:18 pm
Forum: General
Topic: [BUG] NSSI hangs AMI WinBIOS 486 machine!
Replies: 40
Views: 2715

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 ...
by vbdasc
Fri 24 Mar, 2017 7:50 am
Forum: General
Topic: PC-DOS 1.10 and PCem v12
Replies: 64
Views: 5032

Re: PC-DOS 1.10 and PCem v12

Good. But your theory can be proved only via disassembling the IBM PC-DOS 1.10 FORMAT.COM I have disassembled the PC-DOS 1.10 FORMAT.COM. Anyone who wants the IDA database, drop me a line. The program's divided very clearly into two modules: the first 2k are the machine-independent bit, dealing wit...
by vbdasc
Thu 23 Mar, 2017 9:49 am
Forum: General
Topic: PC-DOS 1.10 and PCem v12
Replies: 64
Views: 5032

Re: PC-DOS 1.10 and PCem v12

Good. But your theory can be proved only via disassembling the IBM PC-DOS 1.10 FORMAT.COM It could be additionally confirmed (or debunked) if Battler posts a log of all FDC commands accessing the second side, not only one as he did :) Or if omarsis81 tells us just how much of his 320KB image file g...
by vbdasc
Thu 23 Mar, 2017 9:16 am
Forum: Development
Topic: Introduction && issue with Floppy
Replies: 13
Views: 1189

Re: Introduction && issue with Floppy

older systems like Microport SysV/AT, Xenix, etc, etc, Minix, and even early Linux do not use a BPB at all, so its pure "luck" if the current code catches it or not. With empty file systems, this block is all-zeroes, and so the BPB code catches it and uses the image file size. If it's a b...
by vbdasc
Thu 23 Mar, 2017 8:33 am
Forum: General
Topic: PC-DOS 1.10 and PCem v12
Replies: 64
Views: 5032

Re: PC-DOS 1.10 and PCem v12

I think I might have some idea what is going on, on both real hardware and PC-em v12. Of course, it's only my own theory, so it can or can't be correct :) The manual for PCDOS v1.1 says that FORMAT (without /1 , at least) checks if the drive and/or diskette are double sided. If both are, then the di...
by vbdasc
Thu 23 Mar, 2017 7:45 am
Forum: General
Topic: PC-DOS 1.10 and PCem v12
Replies: 64
Views: 5032

Re: PC-DOS 1.10 and PCem v12

On real hardware, this will go through without errors even on a single-sided floppy (the written bytes will just not be written anywhere pretty much since there's no magnetic surface on the other side) IMHO, this is wrong. Apparently, the one-sided 5.25 inch diskettes are identical to the two-sided...
by vbdasc
Wed 22 Mar, 2017 5:30 pm
Forum: General
Topic: PC-DOS 1.10 and PCem v12
Replies: 64
Views: 5032

Re: PC-DOS 1.10 and PCem v12

With no additional parameters: ie. FORMAT B: results in a successfully formatted 320 KB disk, with the /1 parameter you get a 160 KB disk. But the log of FDC commands posted by Battler definitely indicate that there were issued commands to format at least some tracks on the second side... Just for ...
by vbdasc
Wed 22 Mar, 2017 4:31 pm
Forum: General
Topic: PC-DOS 1.10 and PCem v12
Replies: 64
Views: 5032

Re: PC-DOS 1.10 and PCem v12

With no additional parameters: ie. FORMAT B: results in a successfully formatted 320 KB disk, with the /1 parameter you get a 160 KB disk. But the log of FDC commands posted by Battler definitely indicate that there were issued commands to format at least some tracks on the second side... Just for ...

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