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 All soldering is completed now - just waiting for the straggler parts to come in, burn the rom and say a silent prayer to the retro computer gods before powering up and testing.
+-Nov-2020 - Board is completed and alive! A few issues at the start as follows:
+At first it wouldn't start reliably at all, so I reduced the clock speed from 16MHz to 10MHz. This seemed to work. Spent some time cleaning off flux and debris from the solder side to hopefully solve that issue. The 2 x Oscillator can is positioned perilously close to the pins of the adjacent chips - you have to take care not to touch them when in final position. Possibly the spacing on the board could be changed - but there is a completely redesigned v3 board so unlikely to happen.
+At this stage the board would start but stop every time at the clock/NVRAM setup stage. This baffled me for a whole day. In the end it turned out to be the VT100 emulator terminal (Geoff G) I was using. There seems to be a bug in the terminal firmware where it wouldn't scroll when it got to the bottom of the screen - so I could not see the prompts. I surmised this was the case when I discovered that if I hit enter exactly 11 times, the controller would move to the next step in the bootup process. I waded through the BIOS code and found that the NVRAM setup for the board has exactly 11 items. The workaround was to reset the terminal at this point so it would clear the screen and start from the top again. I am not intending to use the terminal on this board after initial testing, so will leave that for now. Interestingly the terminal later had no issue with scrolling the screen once it had booted into DOS.
+Which, of course, brings me to booting into DOS…. After the usual fun trying to get a working boot floppy made, I found it wouldn't boot. But this time I had a real good idea of what the issue after having a similar experience with the DiskIOv3 ECB board (see above). The issue is that for a 1.44Mb floppy drive you need extra speed to handle the higher data transfer rate through the floppy controller. I had still left the board on 10MHz - so changed back to 16MHz oscillators and now it booted off the floppy ok. Interestingly, all my board cleaning and reseating of ICs while investigating the serial terminal issue seemed to have resolved the issue of not starting at 16MHz - because now it is running correctly every time I boot.
+Next was the PPIDE and CF card interface. I had an existing working set of these, including a CF card with DOS 6.22 installed. But the bios just wouldn't boot from it - or even recognise it. I had a CF card from my Z80 project with CPM on it plugged that in and the bios recognised that ok. Booted off the floppy, used the supplied Fdisk86 utility for the SBC-188 to create a DOS partition, and now the CF card works as C drive ok. I haven't managed to get it to boot off the CF card yet - but I am not expecting that to be a problem. I am making a parproppio board to go with the SBS-188 - so the CF card won't be needed in the long run.
+That's it for now - I will add some documentation below when I finish the project to record poorly documented items for the v2 SBC-188 board - namely what the boot sequence actually does so you can work out what part it is stopping on and also the jumpers.
+Happy for now. This board was easier to get going than most. Partly because the xi8088 and other ECB boards above made it easier for me to recognise where I was going wrong.