i8355 from SDK-85 flakey

allison ajp166 at verizon.net
Tue Apr 27 14:14:25 CDT 2010

Tony Duell wrote:
>> On Monday (04/26/2010 at 06:31PM +0100), Tony Duell wrote:
>>>> I don't suppose anyone has a spare 8355 with SDK-85 monitor burned in
>>>> it do they? 
>>> Alas not. But if the device works if you cool it, can't you read it out 
>>> when it's been cooled? Surely the SDK-85 has some kind of I/O port 
>>> you could dump it to. And then burn the bits into an 8755 as you suggested.
>> Yes indeed.  That will be plan B if Dave is unable to read his 8355 in
>> his PROM programmer.
>> The tty interface on this SDK-85 was built for 20mA current loop so I'll
>> have to either rework that to RS232 or invent a new method to offload.
>> But not a big deal really.
> I would be _very_ supprised if that serial interface doesn't sue some 
> TTL-level serial chip (or bit-banged through a TTL level port) followed 
> by a current loop interface. 
It does not.  The DSK85 does bit bang through the SID and SOD pins
on the 8085 CPU.

> In which case, since you need output only, grab the TTL leve signal at 
> the input to the coverter and feed it into something like a MAX232 (or a 
> 1488 if you have +/-12V suppleis around). 
No need.  The SDK can be via jumpers wired with run RS232 levels
for terminal. A minus 5 to 12 Volt supply is required but we are
talking a few milliamps.

The intel i8085 manuals had the schematic for the SDK85.


> -tony

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