The Sinclair QL Forum

Apparently the PCML TeleDrive interface could read C1 disks but would corrupt them if they were written to by it. They are supposed to be PC compatible, i.e. FAT12 with a PC boot sector and with the same geometry as a PC 720K as formatted by MSDOS. The PCML you see is in the DOS manufacturer field ...

Isn't a .IMA file merely a raw image which you can dd or rawwrite onto a 720K floppy? Yes, but it looks to my untrained eye like the .ima file was not originally a C1 OPD floppy disk. The files contain 'PCML' so they must have been disks made with the other interface. And changing those 2 rows of P...

I've just been experimenting with ImageDisk. With it, I was able to create an image file of my OPD formatted disk containing all the mdv wallet stuff. I was then able to write that image using DOS 6.22 (real hardware) to a fresh 720k disk and that seems to work fine in the OPD, so that's a start - I...

I think I may need a pointer or 2 regarding getting OPD images onto real disks! I found the .IMA image online (attached) and am trying to get that onto a real disk in such a way that the OPD can view the files etc. I note that Windows/DOS couldn't see any content on a disk I created with the OPD, th...

After some faffing today (dodgy FDD cable) I now have a working C1 clone floppy interface connected to my Merlin Tonto. A couple of useful observations: 1. It seems to work just as well with the slightly cheaper WD1770-PH controller chip as it does with a WD1772 variant. 2. It also had no issue with...

Success! My original m/b - the one with the boot loop - had some way out of spec electrolytic caps on it and my cheap Chinese tester also read high vloss (for what it's worth), mainly the blue 33uF ones, of which there are 5. Changed those and tried again, still had the boot loop but with a momentar...

Sorry, it's confusing as I'm talking about 2 different OPD's (both being used with one sort-of working CPU board). Here is the progress, or lack of it, from today. The one with 5 white stripes: On the SRAM chip /CE2 is at batt voltage with no power turned on and it goes low when powered-on. /CE1 goe...

Looking at that pic I had again of the C1 disk controller and even though there is a sticker on the controller chip, I think it's a WD1770, not a WD1772 as they had a later (85) copyright date, not 82. Anyway, thought that might be of interest. Hopefully I'll have a working OPD soon to try it! OPDCo...

The ROMS are I think it 3 parts - the first 64K are a combined OS ROM - so that's ROM A and B ROM C has a header like other application ROM's - so I wonder if this OS Extension is handled as an application ROM - ROM D seems to be the one that may have different code in it and seems to be mostly pro...

SRAM issue I found on my machine was the lack of the POWER-GOOD from the power supply, listed as "shutdown" on the pinout. Check VCC (from the 3V battery) and /CE (from PSU via MOSFET on the left of the board) on the SRAM chip. The SRAM chip has battery 3v on pin 24. There are 2 /CE pins....