After some consideration I decided not to use the plastic casing I had bought for the SBC6120. I thought that a metal casing would be much more appropriate, I found one from Hammond that could fit the SBC and a hard disk.
I want to use the services of these gentleman to design the front and back plane, but at about 20€ per panel, I might go for the front panel only. I found the old digital equipment corporation logo and I'm using Helvetica to do the "pdp-8".
I plan to use the power adaptor and the internal power supply (+5V,+12V) from an old external hard disk casing. The point is to be able to insert in the case any type of IDE hard disk, 3.5' 2.5' or even Compact Flash.
The SBC6120/OS-8 supports a maximum disk size of 2Mbytes, so with 16Mbytes you'd have the equivalent to 8 hard disks of the time and probably be able to fit all the "interesting" software ever compiled/assembled for the PDP-8.
My problem has been finding a IDE 3.5 inch hard disk with a few megabytes, something in the range of 32/64 Mega bytes... it's becoming almost impossible to find hard drives in the Megabyte range...
So to start with something, I went with a old CF of 64 Megabytes and an IDE adaptor, the SBC6120 recognized the drive. These old CFs were bought in a "spare-parts electronics" shop for 1€.I used HyperTerminal (in Windows) and Minicom (linux) to download an disk image, but I had to change the communication protocol is 9600 baud, 7 bits, mark parity, one stop bit (9600 7M1). I also added 100ms delay after each line feed so that the SBC6120 has time to write the sector. I believe this to be a CF problem as it does not have a disk cache, probably with a real hard disk it will work without the delay.
I've downloaded an image provided in the sparetimegizmos site and the next day I checked if it had loaded ok... Boot the SBC6120, type in a DIR and wait for results... Success!! a directory listing appears...
Now I just need to finish the case, find a hard drive and learn how to work with OS-8 :-)
1 month ago