Commodore.ca: The PET, VIC, 128, 64 & More Forum

Hi!

does c128 dcr can work with ega monitor in 80 column mode? i have ega monitor (but it need repair) and i do not know, do i need more ( i mean exactly RGB analog) monitor or i need simply fix my ega monitor to have working set?

and btw can internal 1571 read msdos 720kb disks (DS\DD\80tracks) or i need to format msdos with /track=70 modifier for format program?

AlexVivat wrote: ↑Sat Aug 07, 2021 5:16 pm Hi!

does c128 dcr can work with ega monitor in 80 column mode? i have ega monitor (but it need repair) and i do not know, do i need more ( i mean exactly RGB analog) monitor or i need simply fix my ega monitor to have working set?

and btw can internal 1571 read msdos 720kb disks (DS\DD\80tracks) or i need to format msdos with /track=70 modifier for format program?

Hi,

EGA monitors are theoretically backward compatible with CGA monitors, so they can be used with the C128.
The C128 has a CGA compatible RGB output, which uses digital RGB channels plus an intensity signal.
Analog RGB (VGA) monitors can't be used directly.

There was a short discussion earlier about using modern monitors for the C128 80 column mode here.

Regarding the 1571, the maximum MFM disk capacity that the drive can handle is 340kBytes (in total),
more precisely 170kBytes per side. 720kByte formatted disks won't be read by the drive AFAIK.
You can use the /F:160 option of the format command to create to create a disk with capacity limited to 160kBytes
(170 is not supported) and this can be read by the 1571. Probably the number of sectors are need to limited to 35 too.
But this is only the physical compatibility, you won't be able to read MS-DOS directories/files directly
(e.g. by using the directory command), this requires an sw-tool, without this only raw sector data can be read.

In 1992 I was displayed raw sector data onscreen of an MS-DOS formatted floppy (with reduced capacity),
and character conversion was needed to display the MS-DOS text files correctly on the C128.

LoneWolf33 wrote: ↑Mon Aug 09, 2021 2:50 pm Regarding the 1571, the maximum MFM disk capacity that the drive can handle is 340kBytes (in total),

ahh... sorry... understand...
i simply forgot what 1571 is a double-sided version of 1541 - i.e. 40 tracks on the one side as maximum.
and - because of 35 tracks on one side limit we have 70 tracks on the two sides...

Thank you for this thread, it helped my father a lot!