QuickStart pcb-board to C64 cartridge emulator
tonyp12
Posts: 1,951
I just picked up a Commodore 64C,and it did not come with datasette or floppydrive.
And I don't plan to get them either as they are big and bulky.
I plan to create a pcb add-on board for the Prop Quickstart that plugs in the cartridge port.
That with the help of real-time prop software will emulate 16k eeprom
and also do DMA and write 64k freeze files to the C64s ram.
I take it the address and data bus are all open drain?
As the schematic shows that A12 to A15 have 3.3k pull-up (to 5v), but the other lines have the pull-ups internally in vic-II etc ??
http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/250469-rev.A-left.gif
Q: What would be the best way of handling the 5v to 3.3v voltage level problem?
something like this? http://www.nxp.com/documents/data_sheet/74LVT162245B.pdf
or simple 1k series resistor? Keep in mind I want to be able to spy on data and address lines.
And I don't plan to get them either as they are big and bulky.
I plan to create a pcb add-on board for the Prop Quickstart that plugs in the cartridge port.
That with the help of real-time prop software will emulate 16k eeprom
and also do DMA and write 64k freeze files to the C64s ram.
I take it the address and data bus are all open drain?
As the schematic shows that A12 to A15 have 3.3k pull-up (to 5v), but the other lines have the pull-ups internally in vic-II etc ??
http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c64/250469-rev.A-left.gif
Q: What would be the best way of handling the 5v to 3.3v voltage level problem?
something like this? http://www.nxp.com/documents/data_sheet/74LVT162245B.pdf
or simple 1k series resistor? Keep in mind I want to be able to spy on data and address lines.
Comments
I've love this concept! Keep us tuned into your progress!
OBC
http://www.vesalia.de/e_chameleon.htm
or
http://www.vesalia.de/e_mmcreplay.htm
It just takes a couple of seconds to load the entire RAM from SD.
In about 20 seconds from cold boot you will have "The Great Gianna Sisters" running.
I rarely use the 1541 or the 1530 anymore, I have become VERY VERY lazy!
Btw, have a look at this old thread: http://forums.parallax.com/showthread.php?99751-C64-Datasette-emulator-with-the-Propeller&highlight=datasette
The address buss and control signals are TTL out (or in).
The Data buss is tri-state.
http://www.devili.iki.fi/Computers/Commodore/C64/Programmers_Reference/Schematic/Sheet1.gif
The /DMA should only be held low while the CLK2 is low as VIC-II needs the bus while CLK2 is high.
So I probably should go with bus transceivers and use CLK2 & DMA=enable.