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Post by Cedric on Feb 24, 2014 10:45:41 GMT -8
Hi, I was playing with your nice little 8086 emulator, when I wanted to try to boot CP/M-86 on it. I took the binary ( CP/M-86 binary for 1.44mb floppys) from: www.cpm.z80.de/binary.htmlBut 8086tiny wasn't able to pass hardware detection steps. After investigation, I found that CP/M memory was invalid at a point (invalid instructions on re-mapped code). This led me to something interesting in the bios. int 11h return equipment list, with bit 8 set on 8086tiny bios. This bit is documented as Reserved on some documentations, others state that it means NO DMA if set. So I patched the bios: -equip dw 0b0000000100100001 +equip dw 0b0000000000100001 And CP/M is now fully working. This fix have no impact on FreeDOS. Do you know why bit 8 is set ?
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Post by Cedric on Feb 24, 2014 13:11:11 GMT -8
I've modified a bit the CP/M-86 floppy, adding some tools. Y2k bug inside
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Post by Adrian Cable on Feb 24, 2014 17:10:08 GMT -8
Hi, I originally set bit 8 because I don't support DMA. I figured that, if applications use the bit to check for DMA and then use it because they think it's supported, they will fail.
I have just run a quick series of tests with some applications (including diagnostic/benchmark suites) and it doesn't appear that anything goes wrong with bit 8 clear.
I'll continue to run tests and, if all looks good, I will make this change in the stock BIOS for 1.21.
Thanks!
-Adrian
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Post by Sébastien Kirche on Feb 27, 2014 3:10:32 GMT -8
Which binary did you took exactly for 8086tiny? I also wanted to play with CP/M but none of the different binaries from cpm.z80.de managed to work. (Or say I was not able to make it boot on the cp/m floppies)
Maybe it was due to the problem you are reporting.
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Post by roytam1 on Feb 27, 2014 6:13:52 GMT -8
CP/M-86 in 8086tiny don't scroll when it reach line 24.
and another issue: DR DOSPlus 1.2/2.1 has duplicate inputs besides of not updating screen correctly.
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Post by Adrian Cable on Feb 27, 2014 7:06:18 GMT -8
roytam1, If you email me disk images of both systems, I will take a look and try to fix any display bugs in 1.21.
-Adrian
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Post by Adrian Cable on Feb 27, 2014 14:07:46 GMT -8
roytam1, I have had a look at CPM-86 and DOS Plus 2.1.
For me, CPM-86 works fine. I have no problems scrolling past line 24 and everything seems to update correctly. The only problems I have found is that (1) the clock in the status bar doesn't work and (2) the status bar disappears completely when you CLS. I have traced (1) to a bug in CPM-86's INT 1C timer handler whereby AX is trashed on every timer tick. The effect on 8086tiny's BIOS is to prevent the timer tick being updated. I have put a workaround in my BIOS which will make it into 8086tiny 1.21. But, I worry what other effects the CPM-86 bug may have on "real" PCs if once every 1/20 of a second AX is trashed. (2) is caused by a bug in my BIOS INT 10 handler scroll down function which I have now fixed for 1.21.
I have the same problems as you with DOS Plus 2.1, with duplicated keystrokes and scrolling problems. The problem is that I can't get DOS Plus 2.1 to work at all on *any* emulator (I have tried QEMU, Bochs, fake86) - on all of them it crashes early in the boot process or doesn't recognise the disk is bootable. So I don't have a model of "good behaviour" that I can compare 8086tiny against.
Do you know what "real" PCs DOS Plus 2.1 actually ran on, and/or if the binary we have (mine was from Vetusware) is known to be good?
-Adrian
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Post by roytam1 on Feb 27, 2014 14:34:32 GMT -8
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Post by Sébastien Kirche on Feb 28, 2014 2:02:04 GMT -8
I am sorry to seem dumb, but Adrian, roytam1, would you mind to tell how do you proceed to boot CP/M with 8086tiny?
Whatever CP/M 86 version I have tried, it ends on no result at all, or an error
*** Cannot find CPM.SYS or CCPM.SYS ***
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Post by roytam1 on Feb 28, 2014 2:23:30 GMT -8
I am sorry to seem dumb, but Adrian, roytam1, would you mind to tell how do you proceed to boot CP/M with 8086tiny? Whatever CP/M 86 version I have tried, it ends on no result at all, or an error *** Cannot find CPM.SYS or CCPM.SYS *** did you use the 1.44MB version? www.cpm.z80.de/download/144cpm86.zip
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Post by Sébastien Kirche on Feb 28, 2014 2:41:51 GMT -8
Yes, but maybe the wrong way? When booting the disk image with 8086tiny.exe bios 144CPM86.IMG 8086tiny returns without displaying anything. Using an additional hard drive image or not, with either the hercules or cga enabled bioses.
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Post by roytam1 on Feb 28, 2014 3:00:38 GMT -8
Yes, but maybe the wrong way? When booting the disk image with 8086tiny.exe bios 144CPM86.IMG 8086tiny returns without displaying anything. Using an additional hard drive image or not, with either the hercules or cga enabled bioses. seems you have mismatched 8086tiny.exe/bios pair.
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Post by Sébastien Kirche on Feb 28, 2014 3:25:45 GMT -8
seems you have mismatched 8086tiny.exe/bios pair. I was pretty sure of having used the 1.20 files that you provided... To be sure I just pulled the latest source and bios and rebuild. Minus that the source seem to miss the inclusion of io.h and conio.h, it builds successfully. I can still use Win 3.0, but CP/M-86 144CPM86.IMG still make 8086tiny return without any result.
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Post by roytam1 on Feb 28, 2014 3:46:25 GMT -8
seems you have mismatched 8086tiny.exe/bios pair. I was pretty sure of having used the 1.20 files that you provided... To be sure I just pulled the latest source and bios and rebuild. Minus that the source seem to miss the inclusion of io.h and conio.h, it builds successfully. I can still use Win 3.0, but CP/M-86 144CPM86.IMG still make 8086tiny return without any result. 144CPM86.IMG in 144cpm86.zip is CopyQM image, you have to convert(write) it to RAW image for use.
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Post by Sébastien Kirche on Feb 28, 2014 4:44:46 GMT -8
Gosh, sorry, I missed that point. I have another problem then, since I try to convert the floppy image into a raw disk image by using a MS-Dos 7.1 virtualbox and the CopyQM seem to fail due to "drive not ready" after writing a few sectors. I created the empty floppy image with winimage as I have no "dd" tool here. The image could have a wrong size (else I do not see why the drive could not be ready). Could you confirm your floppy size in bytes? Mine is 1 474 560 bytes, and the DOS can format it successfully. Well, I have found that I am not alone with that kind of problem. Interestingly, that thread deals also with someone trying to make a CP/M floppy with CopyQM on a virtualbox : groups.google.com/forum/#!msg/comp.os.cpm/5vGs825BqaI/KamIDOS0XBEJ *sigh* I tend to think that computer science is not always an exact science, and that there is always one more bug
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