Re: Gemini 80-Bus System
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Re: Gemini 80-Bus System
With the Galaxy MFB system re-assembled, albeit loosely, I was able to boot
Code:
CP/M (Bios 3.4) from the first 5.25 inch disk drive. Code:
**** Not a Gemini MFB System **** Code:
A> B: So whilst not a fully functioning system, progress is steady. |
Re: Gemini 80-Bus System
The boot up sequence I get with 5.25 floppy drive is very similar
Gemini Multiboard Computer System 64K CP/M-80 vers 2.2 (Bios 3.5) A>_ But due to any programs on the disk I cant progress further at the moment. I' going to try the "simon" rom tomorrow to see I can work out the problem with the gotek . |
Re: Gemini 80-Bus System
Bios 3.5 is interesting... I don't have that, I would like to get that archived.
Is your issue simply that the Gotek is using GEMDDDS format and the BIOS is looking for GEMQDDS? The symptoms you describe remind me of when I was trying to use GEMQDDS disks with BIOS 1.4 (GEMDDDS only), they would boot and the directory could be read, however, programs would often not load. Of course you may be using the GEMQDDS images that I created some time back. I'm not sure if you are aware but those disk images were probably not quite right as earlier discussions in this thread have highlighted. These were removed from the library on GlassTTY.com a little while back in an attempt not to confuse things and introduce 'new' formats. In terms of my own Galaxy, I am using Simon 4.1 for booting the floppy and will be trying to get a Gotek going today so that I can archive what I have so far. Obviously my aim is to get the hard drive working in the longer term to form a full MFB system. I will let you know how I get on later today. |
Re: Gemini 80-Bus System
Today wasn't too successful in terms getting the Gotek working or loading MBASIC for that matter and clearly I need to investigate all of these issues further.
Gotek The Gotek boot image I have for CP/M with Bios 3.4 will not boot. In addition, I cannot get the machine to recognise anything other than the first floppy as A: and the Winchester as B: which prevents me from attaching the Gotek as B: or C: etc. Alas, the Winchester doesn't work at the moment either. MBASIC I can boot to a floppy and I have used READCAS.COM to try and load MBASIC from tape, whilst the system read the tape fine it failed to write to the disk. Several attempts were made but each failed in the same way. FORMAT As I only have one system disk for this machine I thought I would try and create another using FORMAT and SYSGEN from the existing disk. Format and verify worked fine but SYSGEN failed when copying the system from the working disk to the new disk. Some successes though as SYSGEN did work when transferring the system from the system disk to an MFB Update Disk that wasn't originally bootable, it is now. As I said, I will continue the investigation and keep the thread updated. |
Re: Gemini 80-Bus System
Sounds like you are trying to run an 829 bios on an 849 system. The bits in the drive select register are different - but bios 3.4 should be able to cope with both I think.
Simple fix will be to jumper the GOTEK as drive C: which cpm should treat as drive B: if I have got my sums right. Then check with configuration as post 322. Alternative is to modify the select routine - it can even automatically determine if it is a GM829 or GM849 by looking at bit 7 of port e5 (Should be zero for GM849 1 for GM829). Thats tricky with multi.mac as several bits of code need to be modified. You might need a later bios for the floppy I am not sure why write to the disk does not work - it could be that the floppy disk controller needs calibration but don't mess with that for the moment. |
Re: Gemini 80-Bus System
Thanks John, I will be able to spend some more time this weekend to look at things again.
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Re: Gemini 80-Bus System
If you have a teac fd55 drive, check jumper MX is removed. with it in place the drive will read data without checking the drive select signal.
https://retrocmp.de/fdd/teac/TEAC_FD...r-settings.pdf |
Re: Gemini 80-Bus System
Hi have now managed to load MBASIC onto one of the backup disks I received with the machine. There were two issues. The first was my fault in not understanding that when loading a file, the file extension should be omited. e.g.
Code:
A> WRITCAS MBASIC.COM Code:
A> READCAS MBASIC Anyway enough babble, I ran your program i.e. Code:
10 FOR I=0 TO 255 STEP 8 Code:
7 7F |
Re: Gemini 80-Bus System
I have modified xbeaver to give the correct table.
Run with xbeaver gem925.cfg -o x to boot mfb (Boots directly from hd without ROMS) xbeaver gem925.cfg -o rx to boot mfb from roms My config file for the gem925 is Code:
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Re: Gemini 80-Bus System
The mystery chip for IC14 looks to be an 74LS20 with pin 1 connected to +VCC. I cannot tell from the photo you sent me but is pin 1 bent under and connected to pin 14?
A few other pins look a bit strange from the photo... From the photo the soldering down the lhs (eg pin1...pin5 or so) looks a bit odd - be nice to confirm that my assumption is correct. PS- when you get the xbeaver emulator running with a gm849m_scsi card can you double check the scsi.bas program - should be the same as the emulator version now. Latest emulator version boots MFB system directly - Simon can boot from the hard disk if there is not a floppy inserted which is hard to do on the emulator as it stands. The analyse program almost works - just identifies as Single not Double Density as my emulator ignores the single/double density in the floppy disk selection. Also track read does not read any data. However as MFB boots the data transfer utilities should work - however the floppy geometry in the config file will need to match. |
Re: Gemini 80-Bus System
Thanks John, I will give it a go. I will also try and check the chip also.
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Re: Gemini 80-Bus System
The emulator is done on a table lookup for the two "undefined" bits the emulator should now match your board.
Truth table for the two outputs are as follows Code:
Readback bit 0x20 gives the following |
Re: Gemini 80-Bus System
1 Attachment(s)
This is the format program I have - the MFB version
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Re: Gemini 80-Bus System
Today I took the R/O tab of the only master disk I have and created a system.cfg that used A (QDDS), B: (DDDS) and C (Winchester). This was written to the system track and saved to a file also. The disk now boots and recognises the 40 track 5.25 drive. The Gotek when connected in place of this drive is also accessed, however, the files cannot be read form any of the DDDS images.
I have several physical disks, one is labelled 'Master disk' and the others seem to be MFB update disks. The dates vary from 1984-1986. Each of the disks has a format utility, however, only the one from 1984 will actually run. The others complain that the system is not using the MFB bios. The error text is correct as I am using the biosfw as biosmfb doesn't fit on a floppy. With 1984 version of the format program the disk gets formatted and verified at 80 tracks double density which I am assuming is QDDS. However, it cannot be read under bios 3.4. As a result of both of the above, I could be forgiven for thinking that the disk/Gotek read issues are related. To take things further, I think it's time to get a Simon ROM version of XBeaver MFB working so that I can have a play with some disk images. |
Re: Gemini 80-Bus System
The two programs you need are gensys - to generate a standard or a mfb system
and config to configure an mfb system eg gensys mfb.cfg to generate an mfb system gensys system.cfg generates a standard non mfb system mfbfw.cfg gives a floppy boot for the mfb system I started with the original image from you to create my two images There are two system tracks 0 and 1 and can contain different systems boot 0 or boot 1 can be used from the command line to boot either the system from track 0 or track 1. use nswp *.cfg to browse the .cfg files. The short files are for use with config Hope that helps. |
Re: Gemini 80-Bus System
In post 330 change gm829m_scsi to either gm849_scsi or gm849m_scsi
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Re: Gemini 80-Bus System
I have been using GENSYS with the floppy to create non-mfb system disks that is fine but prevents running MFB programs such as format.
I now have Xbeaver booting to an MFB system following your config, using the original gm925 disk image and running GENSYS to upgrade it to MFB. My real hardware does not have a working Winchester and the MFBFW.CFG file uses .biosfw which is a non-mfb bios. i currently do not have any floppy disk images that will work with 3.4 the DDDS ones that worked with bios 1.4 do not seem to work with 3.4. If you have a floppy image that works for you under 3.4 MFB I would love to get a copy. |
Re: Gemini 80-Bus System
Tried and failed, then read the "Multi Format Bios Manual". Page 2 states
"A is fixed in type as the winchester...." I tried to generate a .cfg file and then run gensys mfbflop.cfg and get *** Error **** while configuring logical drive A BIOS cold boot does not match your Drive A Unable to proceed So I think you need a winchester to work MFB |
Re: Gemini 80-Bus System
1 Attachment(s)
I have created a bios 3.4 (not mfb) boot disk with disk A and B as floppy (QDDS), C,D winchester
Included in the zip file is the gem925.cfg to make this work. Boots under simon with command line xbeaver gem925.cfg -o xr Hope this helps you. look at bootflop.cfg (PS You will need to check you have the files in the correct places) note the format used is T80.2.10.0.512 if you are going to copy this to a real floppy drive. |
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