CoCoSDC for TRS-80 Color Computer part 4

See also: part 1part 2part 3part 4, part 5 and part 6.

After about a decade in storage, I have finally gotten my Tandy Color Computer 3 set back up. Based on the 2004 copyright of the last item I purchased for it – a Cloud-9 SuperIDE hard drive interface – I guess about ten years ago was the last time I did anything with it. I bought that interface because it has a CompactFlash slot on the side of it, and I liked the idea of using a 128MB memory card as a hard drive rather than big, clunky physical drives. I recall being at a Chicago CoCoFEST! (like the one coming up in April 2015) and leaving the convention site to go buy a CF card, and then spending the evening copying data from my old SCSI SyQuest EZ135 drive disks to it.

I had stopped using the CoCo 3 as my primary computer in 1996, though I still had it set up (and may have even still been running an OS-9 BBS on it) for a year or so more. It’s hard to believe twenty years have passed since the days of 8-bit computers.

Over Christmas break, I set up my CoCo 3, Multi-Pak, floppy drives and SCSI hard drive on a small computer desk in my livingroom next to my TV. There was no room left for a monitor on this modern desk. 80s-style desks usually had an upper shelf for the monitor since old systems took up most of the desk with the computer and external accessories. I guess I forgot how unreadable 80 column text was on a TV via composite video, so I spent another night getting out my 80s computer desk so I could have a spot for my CM-8 monitor. Unfortunately, I had hacked the monitor cable so I could also use it with my MM/1 and it I may have a wire loose – the colors do not work properly (no red, it seems). At least I can read the (off colored) 80 column text now.

I have now spent a bit of time playing with the CoCoSDC. It is significantly faster than a real floppy drive. As a test, I created a new blank disk image as DRIVE 1, and then make DRIVE 0 access my real floppy drive so I could do a backup:


I would listen to the physical drive click and clack as it read data for about five seconds, then see the red LED on the CoCoSDC clip for a mere moment as it wrote to the disk image file on the SD card. Wow – fast.

I also did some tests of booting OS-9 from a real floppy versus a virtual floppy. CoCoSDC blazed through the NitrOS-9 boot screen as if it were booting off a hard drive. I believe I read that it’s still not as fast as the fastest hard drive interfaces, but it’s still quite impressive.

I began writing a quick test program in BASIC that would prompt me to type in an disk image name, and then it would create that on DRIVE 1 and prompt me to do the backup. I wanted to automate my floppy archiving so all I had to do was insert floppy, type a disk image name, and press ENTER. I wanted it do do something like this:

60 BACKUP 0 TO 1
70 GOTO 10

Note: I wouldn’t actually write it that way — I just simplified it for this example.

I ran the program and it worked for the first backup then the program ended. Where was my GOTO?

I had forgotten that in Disk Extended Color BASIC, the BACKUP command clears out the BASIC program so it can use that memory for the disk copy buffer. Oops! No using the BACKUP command in a BASIC program. (On the CoCo mailing list. Robert Gault mentioned that RGB-DOS and HDB-DOS both patched BASIC so this does not happen. Most of my final years using the CoCo were with these alternate DOSes so perhaps that is why I was surprised.)

To solve this, I will either have to write my own backup routine in assembly that I call from my BASIC program, or see if I can find another way to do this from BASIC. I will show you that in the next installment.

To be continued…

5 thoughts on “CoCoSDC for TRS-80 Color Computer part 4

  1. Steve Ostrom

    Hi, Allen. I have read your 6-part CoCoSDC article with great interest. In this fourth part, you mention my exact situation. I have multiple SCSI SyQuest EZ135 drives (Cloud-9 HD system), and need to transfer the files on these to the CF card in the CoCoSDC using a 512K Coco 3 and multipak. Barry Nelson has been helping me with some of the basics, but I was hoping you had success doing the same transfer I need to do. Would you be able to give me some pointers? Thanks! — Steve Ostrom —

      1. Steve Ostrom

        I’m using HDBDOS and not OS9. Could you tell me the steps you used in transferring your data from the SCSI SyQuest EZ135 drives to the CoCoSDC? Thanks!

  2. Allen Huffman Post author

    Ah. I am trying to remember. I know I made disk images under OS-9 of my RGB-DOS EZ135 and CF disks, then used tools from my Mac to split them out to individual .dsk files. But, there is another way. I was given some BASIC code from Darren that showed how to send commands to CoCoSDC even when running RS-DOS or RGB-DOS. You could boot up from the KenTon or Cloud-9, then use these tools to map in the virtual SDC image as Drive 0 and do normal backups. I will have to check. I may have actually written a program to automate this. I know I was working on it. I obviously did it. Let me see what I can dig up.

  3. Pingback: CoCoSDC for TRS-80 Color Computer part 5 | Sub-Etha Software

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