Re: The ultimate UltiMax cartridge

From: Steve Gray <sjgray_at_rogers.com>
Date: Tue, 22 Oct 2013 08:16:49 -0700 (PDT)
Message-ID: <1382455009.61343.YahooMailNeo@web161301.mail.bf1.yahoo.com>
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.
>
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>
>
>

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Received on 2013-10-22 16:05:34

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