Re: [midatlanticretro] Re: TRS 80 Model II Restoration Update
Aaron Brockbank wrote:
Thanks Aaron. Our little group is becoming an international phenomenon!
First off, hello to all MARCHians. Yes, I'm from Australia, and have read this group for about a year. I'm sorry if it's just for those on the other side of the pond, but when Bill needs help with his Model II, I felt that I should jump in now, and properly introduce myself in another message.
Two connectors. It does not hurt to use the terminator anyway, or just to see what happens.
Which version of the FDC/PIO card do you have? One with two connectors (for internal and external drives) or one connector for both? Termination is generally only needed on the 'one for both' connection [the earlier of the two schemes].
I think I have a model from around 1980-81.
The normal boot action (after the "Insert Diskette" notice is cleared from the screen) is for the FDC to be sent a 'Force Interrupt' twice, then all drives are selected and stepped in (towards 76) by five tracks, and then drive 0 only is stepped back out to track 0. If drive 0 is not showing TRK0, the process is repeated twice more - if this fails then it displays ERROR DC. I'm assuming you have the later ROM that attempts to boot from any attached HD before Drive 0. I'm not sure about the earlier ROM, as I don't have a copy to disassemble and see.
There is no BASIC in ROM on a Model II.
I have multiple disks of 1.x and 2.0. What I plan to do next:
If you swap drives, make sure that the last drive on any cable is terminated. What version of TRSDOS are you attempting to bring up: 1.x or 2.0? Both can take some time to do their diagnostics before displaying anything.
1. Test the disks on my known to work Model 12. This way I can eliminate the variable "do these disks work?"
2. Test the expansion drive with the Model 12 (if possible). This way I can eliminator the variable "does the expansion drive work?"
3. Swap out the drive 0 on the Model II, replace with a believed-to-be-new drive that I have had lying around for some time.
4. Test the working disks, and let you all know how it turns out.
I may not get to this until the weekend, I have a packed schedule this week.
http://vintagecomputer.net - where I will also post pics and results.