[Coco] Burning EPROMs, ADOS and ADOS-3

[Rogelio Perea]

Trying my hand at burning a couple EPROMs for my CoCo 1 & 3 setups, got the
customized ADOS and ADOS-3 files (.BIN) ported to my Weven system to
program the 2764s with those images - using a China made TL866CS MiniPRO
burner.

After burning two 2764s - each from its own .BIN file - I installed the
chips on a 26-3029 (with an adapter for the 28 pin to 24 pin scenario
there) and a FD-502 controller (just a drop in on this one). Testing both
on each computer got my only ECB, apparently the CoCo is not reading the
DOS.

Snooping around on an image of the previous EPROM I had on the FD-502
(RSDOS 1.1 modified for 6ms step rate and 'double' sided drive operation),
I see that the first two bytes on this one relate to the ASCII characters D
and K (Hex 44 and 4B); the images for both ADOS and ADOS-e BINary files
have a string of Hex 00 20 00 20 00 20 at the base with Hex 44 and 4B
coming after those... I suspect there is something amiss on the BINary
files I have, lost in the haze of my aging memory  recall something from
years ago about trimming (or padding) the BIN file as read from the CoCo
because of the way it is written on disk, before committing to the EPROM
burner...

Any hints on this will be welcome