Compact OS Personality Card

[reifsnyderb]

While I've got the RAMROM 2023, which provides a lot of options, I decided that maybe a more compact (and cheaper) personality card would be useful. 

 

The card has 2 banks with both banks providing a ROM for the addresses of $C000-$CFFF and $D800-$FFFF.

These banks can be selected by a jumper.  Optionally, the jumper could be removed and a SPDT switch connected.

The RASTime line can be set for RASTime or Phi2 for better left cartridge compatibility.

/S6, /S7, and /EXSEL are also broken out to a header.

While a SST39SF010 chip is standard for the flash ROM, a SST39SF020 or SST39SF040 chip could be used if the normal chip isn't available.

 

I'll get some made up when I order boards next.

 

 

 

 

 

[Beeblebrox]

Nice.

A question. So for using on PAL or NTSC you just flash both roms and can switch between the two using the spdt? I have both NTSC and pal 800 test systems. Would be good to be able to use this board in both easily switching to the required one. 

Edited July 22, 2023 by Beeblebrox

[reifsnyderb]

18 minutes ago, Beeblebrox said:

Nice. Question. So for using on PAL or NTSC you just flash both roms and can switch between the two using the spdt? I have both an NTSC and pal 800 test systems. Would be good to be able to use this board in both easily switching to the required one. 

Yes, it would be possible to flash one ROM bank for PAL and the other bank for NTSC and switch between them.

[reifsnyderb]

Sometimes you don't have a SPDT switch laying around.  So, I was thinking some more about this and added the capability to, optionally, bank select with a SPST switch by adding a 4.7k ohm resistor and just connecting the SPST switch to JP3, pins 2 and 3.

 

I figure that if somebody can solder wires to J3, they can add the resistor and just might have a resistor laying around anyhow.  In actuality, any resistor close to 4.7k ohms would work anyhow.  I'll have to write up a brief instruction sheet for this board as well.

 

 

 

Edited July 22, 2023 by reifsnyderb

[+Larry]

29F010 flash?  Would it be much more difficult/costly to provide 4 OS with a pair of jumpers?

 

 

[reifsnyderb]

3 minutes ago, Larry said:

29010 flash?  Would it be much more difficult/costly to provide 4 OS with a pair of jumpers?

Are you thinking banking should be like the RAMROM 2022/3 boards?  This could be done with a slight change to the jumper arrangement and by adding two resistors.

[+Larry]

Yes, seems better to have 4 than 2.  And (I think) a pair of jumpers to select the OS would be sufficient.  But no rom sockets, switches, battery backup, etc. My 2 cents, anyway.

[reifsnyderb]

Ok.  I've upgraded it to handle 4 banks.   🙂

 

[reifsnyderb]

I had these boards made and they were laying around for a over a month.  Tonight, I put one together and it works.   🙂