A1000 and A1060 Sidecar Mods

[Jeff]

I just installed an NEC V20 cpu in my A1060 sidecar and it runs!
Nec V20 from Ebay Germany
The new CPU is rated at 10 mhz. Currently it is still running at the stock 4.77 mhz as I have not changed the clock crystal yet. It will be interesting to see if the side car will run at speeds close to 10 mhz. From what I have read the V20 is supposed to be 20 or 30 percent faster at the same clock speed although I haven't run any benchmarks yet.

I know it isn't a PPC, but kind of neat nevertheless. I wonder how many people have tried it?

Jeff

[rkauer]

 Maybe you'll have some troubles with synchronization of the CPU if swap the crystal.

 First check if the crystal clock is separated from the main board first.

[adolescent]

I always wanted a V20 for my PCjr but they were too expensive and not 100% compatible.  Edit: Never mind. I guess you had the link in the message.  Let me know how compatible it is.  I'd  guess that clocking it up to the 10MHz would cause a lot of timing issues.

[BuzzBrain]

"by adolescent on 2007/12/20 23:00:38
I'd guess that clocking it up to the 10MHz would cause a lot of timing issues"

True. The xt 8bit bus does clock at same speed as cpu. And I will asume you get problems to run any on the bus.

8 bit ISA or XT bus architecture

Bus width 8-bit
Compatible with 8 bit ISA
Pins 62
Vcc +5 V, -5 V, +12 V, -12 V
Clock 4.7727266 MHz

But I have never done it, so just try

[adolescent]

On the PCjr, if you change the system clock you don't get anything.  There were "accelerators" available for the XT though that would swap out the CPU and a timing chip (which probably just halved the clock).  

[rkauer]

 Then, if you have a way to double the clock signal routed to the CPU only, you are in business again.

[Jeff]

@Everyone

Thanks for the information! It didn't even occur to me that the XT CPU and Bus run on the same clock oscillator. It is very old and running quite well. I won't even attempt to over clock the Bus.

I just need to sort out the hard card issue now and I'll leave it alone. I have an old 65 meg mfm hard card for it, but the bearings are so stiff in the HD that it blows the PS fuse every now and again when trying to spin up:-o  Time to look for another 8 bit controller I guess since mfm drives are extinct:-)

-Jeff

[DamageX]

If you were to speed it up I think expansion cards would be the least of your worries. I remember a lot of cards working at 13MHz. The old memory though would almost certainly become an issue going from 5 to 10MHz.