Re: 6502 BE function ?

["Ing. Franz Glaser" <meg-glaser@eunet.at>]

friedt@lpmo.univ-fcomte.fr wrote:
> 
> I am building an ISA card with a RAM+6502 (no real use, just for fun).
> I want the ISA card to access RAM, and once the RAM is filled, to
> isolate the RAM/6502 busses and let the 6502 work.
> This was easily done with a Z80 as I can switch the data bus and @ bus
> to high impedance.

Yes, but the 6502 has no "bus enable" or "hold" or similar approach
for DMA.

What about looking for a dual port RAM, rhere are pretty chips
available with 4k x 8 and totally independant address and data
bus. You could write a rather simple "move block" program in EPROM
for the "booting", another 32K CMOS - RAM with battery.

Regards,
-- 
Franz Glaser, Glasau 3, A-4191 Vorderweissenbach Austria +43-7219-7035-0
Muehlviertler Elektronik Glaser.  Industrial control and instrumentation
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