booting os/8

[Don North]

On 3/22/2017 5:03 PM, Don North wrote:
> On 3/22/2017 4:25 PM, Bill Gunshannon wrote:
>> Look here: http://www.vcfed.org/forum/blog.php?12663-AK6DN   for info on my 
>> Arduino based RX02 emulator using a microSD card.
>> Works on RX11/RXV11/RX8E as RX01, RX211/RXV21/RX28 as RX02. Passes DEC 
>> hardware diagnostics.
>>
>> Reinhard has done an FPGA based RL01/2 drive emulator, see: 
>> http://www.pdp11gy.com/indexE.html#file:///E:/homepage/indexE.html
>>
>> Don
>> aka AK6DN
>> ______________________________________________
>>
>> I saw that.  I ordered a set of boards from OSHPark today.  Once they come I 
>> will see about ordering the
>> parts and building at least one.  I may wish I had more controillers. :-)
>>
>> I will take a look at the FPGA solution.  But I still have to ask, is there 
>> any reason why it could not be done
>> with an Arduimo like the RX emulator?  I haven't researched it deeply, but I 
>> never thought the RL drive
>> itnerface was all that complex.
>>
>> bill
>>
>
> If you are still interested I still have blank PCBs for $10 each (either 2n7K 
> or 8641 based), plus Sparkfun microSD adapters $5 ea, and then shipping.
>
> OSHpark is good (I use them for proto) but it will cost you something like $75 
> for three boards since they are 4 layer. Let me know if you are interested.
>
> The RL0x interface is very different and requires some kind of high speed 
> signal decoder to implement (Reinhard did it in an FPGA plus an embedded CPU).
>
> The RX0x interface is driven by the drive as the master, so no high speed 
> logic is required on the Arduino side, just bit banging I/O ports.
>
> Don
>
Just checked my stock ... I have (5) 8641 based PCB, and (10) 2n7k based PCB 
left, and corresponding microSD adapters.

The 2n7K vs 8641 designs are functionally compatible (100% same software); the 
revised 2n7K design uses discrete transistor O.C. drivers and
HCT14 RCVRs in place of the 3x8641 (which are more or less unobtanium at this 
point, unless you have a well stocked DEC stockroom).

The two designs work the same, there is no discernible difference between them 
operationally.

As an aside I source Arduino Mega2560s from Amazon, you can get 100% a 100% 
compatible clone for $10-$12 vs $45 for a 'genuine' Arduino Mega2560.

Don