14-10-2024, 02:37 PM
Hey All.
Just a minor update for now.
Nothing much to show, but I have a couple of weeks to make some further progress.
Working through some bugs at the moment before getting on to testing the HDMI output later in the week.
* The keyboard was not working with the second processor (68sz328). I found and fixed a timing issue with the
implementation of the 6545's (CRT controller) registers that was not handling the faster access times that the
second processor operates at. The keyboard now works and I can now access the 'Boot manager' than runs
on the second processor to let you choose which disk image to boot from, and what other images to load as
further drives. Those of you with a Premium Plus or 256TC-SE will know the Boot Manager.
* Added a [Q]uit option to the boot manager software so that it is not necessary to Save the boot configuration
if you don't want to, and just continue with booting.
* The SDcard was intermittent - sometimes it would be recognized on power up or reset, sometimes not. This was
a software issue. I had earlier optimized the SDcards SPI interface routines for speed, but this caused the card
responses at initialization to be intermittent. Basically the SPI clock was much faster than required (100-400Khz)
for proper initialization. Once initialized the clock can then be set higher (up to 20Mhz). So I re-wrote the routines
so that the SPI clock would be slower for init phase, and then use the optimized routines after that.
The machine now sees the SDcard every time.
* Fixed a bug in the video raster generation logic that was causing incorrect screen display which changed from build to
build of the FPGA logic. A couple more bugs to look at in the screen section next.
Just a minor update for now.
Nothing much to show, but I have a couple of weeks to make some further progress.
Working through some bugs at the moment before getting on to testing the HDMI output later in the week.
* The keyboard was not working with the second processor (68sz328). I found and fixed a timing issue with the
implementation of the 6545's (CRT controller) registers that was not handling the faster access times that the
second processor operates at. The keyboard now works and I can now access the 'Boot manager' than runs
on the second processor to let you choose which disk image to boot from, and what other images to load as
further drives. Those of you with a Premium Plus or 256TC-SE will know the Boot Manager.
* Added a [Q]uit option to the boot manager software so that it is not necessary to Save the boot configuration
if you don't want to, and just continue with booting.
* The SDcard was intermittent - sometimes it would be recognized on power up or reset, sometimes not. This was
a software issue. I had earlier optimized the SDcards SPI interface routines for speed, but this caused the card
responses at initialization to be intermittent. Basically the SPI clock was much faster than required (100-400Khz)
for proper initialization. Once initialized the clock can then be set higher (up to 20Mhz). So I re-wrote the routines
so that the SPI clock would be slower for init phase, and then use the optimized routines after that.
The machine now sees the SDcard every time.
* Fixed a bug in the video raster generation logic that was causing incorrect screen display which changed from build to
build of the FPGA logic. A couple more bugs to look at in the screen section next.