Xerox 820 disk format
Xerox 820 disk format
I unsuccesfully tried to build a valid disk image for the Xerox 820.
I'm 90% sure the definition is correct:
static disc_spec x820_spec = {
.name = "Xerox820",
.disk_mode = FM250,
.sectors_per_track = 18,
.tracks = 40,
.sides = 1,
.sector_size = 128,
.gap3_length = 0x2a,
.filler_byte = 0xe5,
.boottracks = 3,
.directory_entries = 32,
.extent_size = 1024,
.first_sector_offset = 1,
.has_skew = 1,
.skew_tab = { 0,5,10,15,2,7,12,17,4,9,14,1,6,11,16,3,8,13 }
};
For some reason MAME doesn't like the created files, so I'm not pulling this table in appmake until we get it tested in some way.
I'm 90% sure the definition is correct:
static disc_spec x820_spec = {
.name = "Xerox820",
.disk_mode = FM250,
.sectors_per_track = 18,
.tracks = 40,
.sides = 1,
.sector_size = 128,
.gap3_length = 0x2a,
.filler_byte = 0xe5,
.boottracks = 3,
.directory_entries = 32,
.extent_size = 1024,
.first_sector_offset = 1,
.has_skew = 1,
.skew_tab = { 0,5,10,15,2,7,12,17,4,9,14,1,6,11,16,3,8,13 }
};
For some reason MAME doesn't like the created files, so I'm not pulling this table in appmake until we get it tested in some way.
Re: Xerox 820 disk format
Do you need has byte size extent as well?
Re: Xerox 820 disk format
Wow you probably spotted the problem!
Re: Xerox 820 disk format
It worked !
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Re: Xerox 820 disk format
I'm always amazed at the density of platform-specific knowledge that is stored in this forum and its users :-)
Surgically exact, pinhead specific knowledge
Surgically exact, pinhead specific knowledge
Re: Xerox 820 disk format
and the 10% of the definition was not correct
but technically it was not wrong, just not complete
but technically it was not wrong, just not complete
Re: Xerox 820 disk format
I think it was me pulling the code to get the x820 booting again after the big rework the mame team did on the floppy disk formats.
I suspect the BigBoard could be booting too *if* a single side 40trk boot image existed.
All the disk images available are for 8" drives or 5" HD drives formatted with 77trk, 26 sectors
I suspect the BigBoard could be booting too *if* a single side 40trk boot image existed.
All the disk images available are for 8" drives or 5" HD drives formatted with 77trk, 26 sectors
Re: Xerox 820 disk format
I can confirm the statement above.
The current MAME emulation is slightly messy but allows the Xerox820 (first version) to be configured with BIOS mods allowing to boot 77trk disks, including the BigBoard CP/M.
The emulation engine in MAME shares most of the code between x820, bigboard,mk82 and mk83, showing they were VERY close relatives.
I'll add the 8" floppy format
To access to 8" floppy disks with MAME:
- start MAME with the "x820" machine type
- change the machine BIOS to "MICROCode SmartROM v2.3"
- enter to "Slot Devices" and change the floppy disk types from "sa400l" to "sa800"
Now (not before!) enter in File Manager and open the floppy disk image.
Valid boot disks in 8" format are in the Dunfield website, the suggested BIOS will properly boot most of the BigBoard or Xerox 820 (first release) disk images:
http://dunfield.classiccmp.org/img42841/system.htm
Assigning a wrong floopy disk format before changing the disk drive type and resetting the system could crash MAME.
Be patient, and try again
The current MAME emulation is slightly messy but allows the Xerox820 (first version) to be configured with BIOS mods allowing to boot 77trk disks, including the BigBoard CP/M.
The emulation engine in MAME shares most of the code between x820, bigboard,mk82 and mk83, showing they were VERY close relatives.
I'll add the 8" floppy format
To access to 8" floppy disks with MAME:
- start MAME with the "x820" machine type
- change the machine BIOS to "MICROCode SmartROM v2.3"
- enter to "Slot Devices" and change the floppy disk types from "sa400l" to "sa800"
Now (not before!) enter in File Manager and open the floppy disk image.
Valid boot disks in 8" format are in the Dunfield website, the suggested BIOS will properly boot most of the BigBoard or Xerox 820 (first release) disk images:
http://dunfield.classiccmp.org/img42841/system.htm
Assigning a wrong floopy disk format before changing the disk drive type and resetting the system could crash MAME.
Be patient, and try again
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Re: Xerox 820 disk format
+sound library for the Xerox 820ii
This one was difficult to test because I can't boot the 820ii, I worked around the problem borrowing the sound emulation and using it on the x820.
Not a standard way to play sounds really, OUTs to 2 different addresses to toggle the speaker high/low, the written data doesn't matter.
I think I found something similar already, but I can't remember what it was (perhaps it was an S100 board).
This one was difficult to test because I can't boot the 820ii, I worked around the problem borrowing the sound emulation and using it on the x820.
Not a standard way to play sounds really, OUTs to 2 different addresses to toggle the speaker high/low, the written data doesn't matter.
I think I found something similar already, but I can't remember what it was (perhaps it was an S100 board).
Re: Xerox 820 disk format
The display.
I haven't checked the earlied X820 model yet, but I suppose that the paging logic was the same.
The video memory will get paged in at $3000, 80x24 characters.
The Xerox820ii should have also a 4x4 "business graphics" (=blocky ) mode.
Dom, probably I asked already but, is there existing code I could copy from ?
Just for fun, do you prefer to play with it yourself ?
I haven't checked the earlied X820 model yet, but I suppose that the paging logic was the same.
Code: Select all
; (F293) crtoff - turn crt ram off.
crtoff:
di ; lock pio access
in a,($1C) ; syspio: get pio status
crtof1:
res 7,a ; reset crt bank enable
ei ; unlock pio access
crton1:
out ($1C),a ; syspio
ret
;(F29C) crt on - turn crt ram on.
crton:
di ; lock time-out interrupt
in a,($1C) ; syspio: get pio status
set 7,a ; enable bank
jr crton1
;(F2A3) crt ldir - block move from/to crt memory.
; Entry:
; HL Source address
; DE Destination address
; BC Number of bytes to move
; A = 0 - Move crt ram to crt ram
; A < 0 - Move sys ram to crt ram
; A > 0 - Move crt ram to sys ram
The Xerox820ii should have also a 4x4 "business graphics" (=blocky ) mode.
Dom, probably I asked already but, is there existing code I could copy from ?
Just for fun, do you prefer to play with it yourself ?
Re: Xerox 820 disk format
Send me the ROMs and bootdisc and I’ll have some fun.
Re: Xerox 820 disk format
https://oldcomputers-ddns.org/public/pu ... index.html
40 trk disks, e.g. 820sys5 are the easiest one to boot on x820.
Please note that only the x820 option will work correctly.
The 820ii FDC emulation is not complete and won't boot, I also suggest to avoid wasting time on the other variants (BigBoard, etc..).
I'm trying to get the BigBoard II boot, but the emulation is probably at an earlier stage, the display controller requires a "paged" ROM, after a minimum of emulation code hacking, the first slice is picked:
8002.u52 WRONG LENGTH (expected: 00000800 found: 00002000)
8002.u52 WRONG CHECKSUMS:
EXPECTED: CRC(fdd6eb13) SHA1(a094d416e66bdab916e72238112a6265a75ca690)
FOUND: CRC(a1dc4f8e) SHA1(873fd211f44713b713d73163de2d8b5db83d2143)
40 trk disks, e.g. 820sys5 are the easiest one to boot on x820.
Please note that only the x820 option will work correctly.
The 820ii FDC emulation is not complete and won't boot, I also suggest to avoid wasting time on the other variants (BigBoard, etc..).
I'm trying to get the BigBoard II boot, but the emulation is probably at an earlier stage, the display controller requires a "paged" ROM, after a minimum of emulation code hacking, the first slice is picked:
8002.u52 WRONG LENGTH (expected: 00000800 found: 00002000)
8002.u52 WRONG CHECKSUMS:
EXPECTED: CRC(fdd6eb13) SHA1(a094d416e66bdab916e72238112a6265a75ca690)
FOUND: CRC(a1dc4f8e) SHA1(873fd211f44713b713d73163de2d8b5db83d2143)
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Re: Xerox 820 disk format
Unfortunately I've failed at the first hurdle. The only discs that are accepted by the version of mame I'm running just result in a hexdump.
Edit, found a working one here: http://bitsavers.org/bits/Xerox/820/5_inch/
Edit, found a working one here: http://bitsavers.org/bits/Xerox/820/5_inch/
Re: Xerox 820 disk format
you might boot also the other ones, but you need first to select the "SmartaROM" BIOS, change the drive type to sa800, then reset and finally open the floppy images
Re: Xerox 820 disk format
I've added in support for --generic-console - I've conveniently ignored the scroll register.
I've also added a 80x24 super lores display which isn't that great since there's blank pixels around the square.
I've also added a 80x24 super lores display which isn't that great since there's blank pixels around the square.
Re: Xerox 820 disk format
Super fast!
IMO the idea of an 80x48 mode using comma and apostrophe wasn't that bad ?
IMO the idea of an 80x48 mode using comma and apostrophe wasn't that bad ?
Re: Xerox 820 disk format
It is very nice to see the Dallas game run (and play sounds) on the Xerox 820!
In theory the x820ii is slightly different, because it the only one supporting the 1bit sound and the 4x4 blocky graphics, but at the moment it is not much an issue, because no working emulators exist for it, I'm not expecting further development unless someone owning the original machine will jump in, here or in the MAME team.
In theory the x820ii is slightly different, because it the only one supporting the 1bit sound and the 4x4 blocky graphics, but at the moment it is not much an issue, because no working emulators exist for it, I'm not expecting further development unless someone owning the original machine will jump in, here or in the MAME team.
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Re: Xerox 820 disk format
That's an interesting one, I'll add a graphics mode that will implement 80x48 and fat-pix will switch to 80x24. I think I've seen some targets which have the "volume bar" graphics and an inverse flag but not the usual 4x4 or 3x2 so it'll be useful there.
Re: Xerox 820 disk format
....and I've done just that using a couple of characters that work better than ` and ,
Calling gfx_set_fatpix(1) switches to the 80x24 mode detailed above.
Calling gfx_set_fatpix(1) switches to the 80x24 mode detailed above.
Re: Xerox 820 disk format
fantastic! if it gets generic we can use it in several cases.
Re: Xerox 820 disk format
Yeah, it's reusable - just a case of adding a table with the 4 characters and including gfx_gencon2.lst - we probably ought to redo Kaypro83 to use it rather than the custom code it's got.