Flashy Clock - Yet another DEV board

[exxos]

It seems to be working so far

I have TOS104 Programmed in bank zero, and TOS206 in bank 4. So when I set register 7F in the crappy clock software to 00 and press reset, then boots in TOS104. If I set the register 7F to 11 and press reset, it then boots in TOS206.

Similar with powering off the machine as well. Whatever the bank selection made, when the machine is powered up, the PLD reads the RTC's NVRAM register 7F and latches that date into the flash bank selection registers (1 of 4 banks).

Technically there is two scenarios which come into play now.
When programming the flash bank, the selection needs to be made in software to which bank to program. In which case the bank would just need to be selected without resetting the machine. Or if literally just changing the flash bank the machine does need to be reset. So I need to think about how to implement it all.

The flash banks can only be programmed when the motherboard ROM's are in use. I opted for this method as there is no way to boot from the flash originally as it will be blank, so the motherboard ROMs have to be used anyway. Also if someone manages to brick the flash, they can always fall back to the motherboard ROMs to program the flash.

On the board there is a jumper called "ROM_DIS" , so likely what I will do, is to base the reset or not on that jumper setting. In that, if the flash banks are in use, the bank can be changed, and the machine will automatically reset, and boot up whichever selection is made. Then if the jumper is set to boot from the motherboard ROMs, we will assume the banks are being programmed and we will not reset the machine.

It is probably worth noting again that there are 4 flash banks which can hold 4 TOS versions. Plus you can still use the motherboard ROM, so we have 5 TOS versions. But technically if you have one of my DUALTOS boards, the technically could have 6 TOS versions

This probably sounds confusing, but I will get @Icky to do a video on this soon, It is actually really simple usage

[Icky]

Cool it works

[Icky]

Whilst @exxos has been working on the firmware I have been working on fixes to the board and got carried away reducing the plugin RTC module down onto the board.

Here are some renderings of Flashy Clock v4. The first shows an assembled board with CPU on top. It is now reduced down to a small slither on the top right for the ROM_DISBLE jumper and JTAG

Screenshot 2019-12-11 at 00.02.56.png (177.45 KiB) Viewed 3512 times

Have managed to squash everything in between the DIL headers including the battery and XTAL. The 4x jumper holes on the left are for the ALT-RAM board to stack on top. There are also some extra jumper holes just above the battery (am still working on this section) for connecting to the H4 so that the board can run without a CPU plugged in i.e. using the H4 PLCC CPU.

Screenshot 2019-12-10 at 23.59.07.png (564.71 KiB) Viewed 3512 times

This shows the battery with the CPU chip on top it's all a snug fit.

Screenshot 2019-12-11 at 00.01.46.png (86.27 KiB) Viewed 3512 times

As mentioned by @exxos this board supports 4x ROMs on-board and also allows you to still use the motherboards original ROMs. ROM_DISABLE will allow you to always boot from the motherboard ROMs, where as enable allows you to boot from any of the 4 banks set by software. Thus if you have an H4 its a simple plug and play solution and will allow you to have the 2x ROMs on the H4 itself and 4x ROMs on the Flashy Clock board totalling 6x ROM banks.

This will be the version the lucky winner of the H4 Build completion https://www.exxosforum.co.uk/forum/viewt ... =78&t=2225 will win.

[stephen_usher]

Are you sure it’s a good idea putting the battery, which will have to be changed, underneath the CPU? Having to pull the chip every time the battery goes flat seems like a recipe for disaster in the long term. (I know it looks nicer)

[Icky]

@stephen_usher - Good question. For the H4 this is not a problem as the CPU will not be on the board. In my experience (can stand corrected) these batteries last a while, however we could add a header on the top right for people to add on a battery pack like in the Mega STE's. Although lifting out a CPU from a plug-in header isn't too difficult I loose count of the times I do it. Yesterday I think I removed and placed, on and off plug-in boards, about 4-5 CPUs.

[PhilC]

I cant believe just how much smaller this is than the original board, well done guys.

[stephen_usher]

@stephen_usher - Good question. For the H4 this is not a problem as the CPU will not be on the board. In my experience (can stand corrected) these batteries last a while, however we could add a header on the top right for people to add on a battery pack like in the Mega STE's. Although lifting out a CPU from a plug-in header isn't too difficult I loose count of the times I do it. Yesterday I think I removed and placed, on and off plug-in boards, about 4-5 CPUs.

Ah, but you're an expert. I'm just thinking of people who are less adept. I can just the the support problems if they go on sale.

It reminds me of some of the Dell small form factor PCs which require you to half dismantle the machine and remove the CPU heatsink and cooling vents just to get to the BIOS battery. *shudder*

[exxos]

That may be true, but if they can't do that job, they gonna have bigger problems unsoldering the CPU and soldering in the board and fitting it in the first place

Also as Icky mentions, all these projects now are focused on being fitted to the H4. They will all be backwards compatible with a STFM etc, but of course, if people don't have the H4 , there will be some small caveats on fitting to "lesser" machines anyway.

Due to space limitations on the H4 expansion ports ( I think someone posted a image of Lightning basically swamping out all the other expansion ports?) we need to get all the expansion boards as small as possible so more than 1 expansion board can be fitted at a time into the H4.

[PaulJ]

Excellent board guys. Can't wait for the extended memory option board. Since the target board for these daughter cards is the mongrel the purchaser will most likely have built the Mongrel and have the skills to deal with the construction or know someone who does. I would believe using these option boards on a STxx would incur an additional risk of issues due to increased noise levels and power instabilities with STxx boards.

[stephen_usher]

How about instead of having the coin cell under the CPU you have a two pin header on the side into which you can plug a battery holder of your choice via a wire, in the same way as the TT and MegaSTE? That should allow the height to be slimmed down a bit more and shouldn't take much more space around the socket. The choice of coin cell or 2xAAA in a holder would be up to the user then, as would its location.