6th June 2021
Jeff reminded me that its been more than a year since we designed ROMX! Right now, we are working away at assembling more stock of ROMXc and ROMX plus a panel of ROMXe for initial testing. There are a couple more projects in the wings as well.
Jeff's been busy with firmware and introduced per image acceleration (for those who have ZIP chips) with firmware release 0.994A. This is pretty neat, and is demonstrated by Jeff in this video :
Javier has also taken a look at this and gives a great demonstration of the acceleration settings, but also the ease of uploading custom ROM images in his latest video :
ZIP CHIP users who update to 0.994A must also replace the following images on their ROMXc with the ones included with the 0.994A disks:
- Raster Blaster
- DOS 3.3 Fastload + Link
- ProDOS 2.4.2 for ROMXc
- ProDOS 2.4.2 with Bitsy Bye
Also you would need to replace ROMX.CLK.SYSTEM with the 0.994A version on any ProDOS disks where you have included it.
If you update to 0.994A and don't have a ZIP CHIP, there is no need to replace the above apps.
One of the neat apps included with version 0.994A is a CLOCK SET utility that introduces setting of the day-of-week and also allows you to adjust the oscillator trim that is built into the RTC. The OSCTRiM register contains a 7-bit value plus a sign bit thus allowing a trim value between -127 and +127. Each unit represents roughly 1PPM (part per million) which translates to about 1 second every 11 days. When adjusting the trim, you can bypass setting the clock by first pressing "N" and then enter just the trim value. Note that the current trim setting will be displayed to the right.
To adjust your clock accuracy, start by setting the clock to a known good time source (such as https://time.is). Then check the time again 11 days later. If the ROMX clock is running slow, you need to lower the OSCTRIM value; if running fast, then increase it. If the clock is off by more than 1 second, change the value by 1; if off by more than 2 seconds, change it by 2, etc. This should bring the clock into the proper range. Note that temperature changes and other factors will also determine the ultimate accuracy of the clock but you should be able to adjust the trim to achieve less than 30 seconds drift per year.