OT: But for the vintage CPU guys: Intel 8008 clock

[Philip Pemberton]

Ethan Dicks wrote:
>> from the site "Every year [Len Bales] designs and builds a new clock. His
>> 2006 clock runs on the classic Intel 8008 microprocessor. The design is
>> definitely not for the faint of heart...
> 
> Wow, that's a lot of breadboarding.

I did roughly as much when I built up my 6502 board. If memory serves, I had a 
GAL16V8AQ PLD (address decoder), 28C64 EEPROM, and a RAM chip on one chunk of 
breadboard, a W65C02A (WDC CMOS 6502) on another, and a TI 16C550 UART on the 
third.

I don't think I got the breadboarded version stable at much more than 2MHz, 
but the Eurocard version runs quite nicely at 10MHz, with a full complement of 
I/O cards (CPU/RAM/ROM, UART, SP0256A-AL2 speech synthesizer).

I've never plucked up the courage to put a scope on the backplane, though. 
Phi-0 and Phi-2 are probably rather messy, and I suspect SEL0 thru SEL3 aren't 
in much better shape...

Schematics (hand drawn with a Rapidograph, no less!) are at 
http://www.philpem.me.uk/elec/6502/ if anyone wants to have a look.

Ultimately, I got to the point where I could make it run EhBASIC and speak, 
then more or less ran out of things to do with it. At some point, I really 
should tie a MOS 6581 "SID" sound chip to the bus and see what happens... Or 
maybe a disk controller...

-- 
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/