[Coco] 2764 EPROM

[Roger Taylor]

At 08:10 PM 9/7/2007, you wrote:
>>From: "Bruce W. Calkins"
>>Subject: Re: [Coco] 2764 EPROM
>>Date: Fri, 7 Sep 2007 19:03:06 -0400
>>
>>Yes, the Radio Shack/Tandy  FD-502 takes a 2764, or with a hack, the 27128.
>
>The FD-502 can actually accept a 2764, 27128, 27256 or 27512, so 
>long as you program your code into the highest 8K address space of 
>the device. This is because Tandy tied the A13, A14 and A15 address 
>lines to +5V. If you want to use 16K of the EPROM, then you need to 
>disconnect the A13 pin from +5V and connect it to the A13 pad on the card edge.
>
>I often use an SST 27SF512 Flash EEPROM in my FD-502 to test 
>modifications to Disk Basic. It beats having to use a UV eraser.
>
>Darren



This is probably the EEPROM type I'm looking for then.  I'll be 
playing around with some embedded projects and since we have no 
current cartridge port project boards, reusing an old floppy 
controller seems like a quick way of building a "ROM Pak".  I am also 
looking at building these ROM Pak boards myself or having them built.

WE NEED these boards, preferrably around the size of a ROM Pak PCB, 
but larger wouldn't hurt.  Cases aren't a concern right now.  I also 
have an old Disto Mini Controller (floppy) board that I desoldered 
everything from many years ago which might make a good starter board 
in my projects.  Anyway, having a good volume of these board types 
made will give the CoCo world the ability to make new ROM Pak games 
or apps.  Some might ask, "why?, we have floppy disks", but anybody 
interested in reusing old CoCo's not being used anymore, for embedded 
projects will want a simple and immediate-on solution in case the 
power trips, things will come back up and start running again just 
like Disk BASIC does.

This leads me to another question.  Is there anyone here with the 
skills and time who could quote me a price for about 25-50 of these 
boards, made as small as possible but big enough to extend out of the 
CoCo enough to grasp.  I can solder in the ROM sockets, etc.  Or, if 
someone can design the PCB file for such a board in a format that can 
be submitted to a PCB company, that is an idea as well.  All it needs 
to do is map in the ROM at address 49152 decimal and ofcourse, 
autostart.  Maybe a dip switch can be put on the autostart line to 
control that feature.

Ofcourse, if Cloud-9 already sells an affordable device that can let 
me load in my own ROM in the Disk BASIC area, this would be a 
solution for a limited number of projects.



-- 
Roger Taylor