I tried it with an EPROM in a 610 and it didn't work. I assume it's down to running at 2mhz - the timing of an EPROM based solution is marginal already. I also tried the SuperPLA in a 720 and that works great.
Rob
Very interesting work, is it possible to make a 6509 or 6510 etc using a 6502 and additional circuitry or is that a complete dead end?
I'm not too up on creating processors etc using modern day chips, so was wondering if you could implement old tech in some way.
Yes, theoretically it's possible. The 6510 would be easiest since it's just a 6-bit I/o port mapped to $00 and $01. The 6509 is a little tougher because there are two ports (execution register and indirection register) plus two opcodes are modified. Those two ports control the processor BANK address lines. This means you need to monitor when those commands are executed in order to set the proper BANK. You can use the 6509 SYNC pin that tells you when the cpu is fetching an opcode, and if you see of the opcodes you set the bank lines properly. If you look on 6502.org you can find the datasheets for both CPU's. There is a block diagram in the 6509 datasheet that shows the additional function blocks.
Ultimately/eventually someone will have to build a replacement 6509 using an FPGA as machines break down and chips become impossible to find.
Steve
Looking at the 6509 how feasible would it be to use a 8502 with extra circuitry as it looks very similar to the 6509.
It has the ability to run at 2mhz as the 6509 too!
The 6509 use p0-p3 for the banking and the 8502 has p0-p6 but lacks the ϕ2 pin what difference would that make?
Well they say patience is a virtue!! After the kind offer of a 6509 from Billdeg I had to decline due to high shipping costs from America.
But on the plus side I picked up another low priced CBM 710.
I plugged her in but bang went the power supply, the usual line filter (rifa 0.6uf) had gone pop with lot's of smoke that filled the house (wife was happy!)
With my fingers crossed and after swapping the motherboard into my 710 up came the boot screen Happy Days! :D
I plugged in the Calc Result cartridge and connected up the 8250lp and everything loaded up fine!
Nice! I have a machine that went poof as well. Gotta get a replacement filter. I also have a 710 motherboard in need of a cpu at some point.
Steve
Steve on your B715 is the power supply the same as the low profile with an external funk enstor line filter or the same as the high profile type with the Rifa line filter caps inside the unit?
It's the same as the high profile power supply.
Steve
Have you opened it up to see which one has gone? mine was the RIFA 0,6 uf and it was glued to an inductor.
Absolute pain in the backside to take out, had to desolder and take out the socket and the same with the switch.
The filter cap had completely split apart it's casing, the smaller filter cap looks intact though.