Hi, Sounds great. I wonder if you can try substituting a 32K ram chip. http://home.arcor.de/armin.diehl/eprsim/UM61256.pdf It comes in "skinny dip" format which is smaller and might give extra room on the board to add another chip to take advantage of it (if feasible) I ordered these from ebay: http://www.ebay.com/itm/290815749900 Do you use any protoyping boards to do development (ie: 8-bit baby, vannessa's board, etc). I'd like to use a solderless breadboard to do some stuff (like I used on ColourPET), but connected to the cartridge port, so something that lets you connect a ribbon from the port to the breadboard. Any ideas? Steve >________________________________ > From: Michał Pleban <lists@michau.name> >To: "cbm-hackers@musoftware.de" <cbm-hackers@musoftware.de> >Sent: Tuesday, October 22, 2013 4:47:25 AM >Subject: The ultimate UltiMax cartridge > > >Hello! > >Yesterday I was on a 8 hour train journey, so to kill time I designed >the UltiMax cartridge and laid out a PCB for it. It looks like >everything just fit on the cartridge PCB I got from Ruud. > >Here's how it is supposed to work. Sorry I don't have a schematic yet; >generally I don't believe in schematics and I always lay PCBs without >one. Maybe on a next train journey I'll have time to draw it :-) But >here's what I got on the PCB: > >* A 27C801 EPROM. >* A 6116 SRAM. >* All needed address and data lines connected properly to these. >* A 74LS273 resettable latch, with outputs Q0-Q5 going to high address >lines of the EPROM, and Q7 used as below. >* A 74LS08 and 74LS04 for glue logic. > >The idea is that initially, the latch sits at the /EXROM line. This is >done as follows: > >74LS273.CLK = /EXROM & 74LS273.Q7 > >So as long as we write values to the latch with it 7 set to 0, the latch >still operates. But if we set bit 7 to 1, the latch becomes inactive. In >such case, the RAM will become active, because: > >6116.CS = /EXROM & ! 74LS273.Q7 > >So to enable a cartridge, we write correct bank number to the latch ORed >with $80. The latch disappears and the RAM takes its place. > >Of course, there are some other needed signals: > >27C801.CS = /ROMH & /ROML >27C801.A13 = /ROML >27C801.OE = 6116.OE = ! RW >6116.WE = RW > >I need to verify the PCB now and I will send it for prototype production. > >Regards, >Michau. > > Message was sent through the cbm-hackers mailing list > > > Message was sent through the cbm-hackers mailing listReceived on 2013-10-22 16:05:34
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