Q: Is there a reference to the SS-50 standard?
A: There is no standard other than what loose specifications manufacturers followed when designing boards. The first SS-50 machine was from SWTPC and had a 6800 processor, so the bus was closely designed around that processor’s architecture. When SWTPC added a 6809 board they more-or-less followed the previous use of most pins on the bus, but also changed the purpose of others. Other companies began making compatible boards based on what was already on the market.
Q: Why are there so many pieces to build a complete system?
A: This a real clone, so it has an SS-50 bus for the CPU and memory, and an SS-30 bus for the peripheral devices. The original systems had a motherboard, CPU board, CPU board, memory board, serial console board, terminal, etc, which means our system does too. Back in the day, people were driven by cost (just like now) so systems were modular, allowing someone to buy exactly what they wanted (or could afford) while building their system.
Q: What is the bare minimum to get started?
A: The motherboard contains the framework for the other boards to plug into, and is required. To use a terminal for a console, a serial board is required. We have two CPU boards, one having a 6800 and 16K of RAM, and a 6809 CPU with 128K. Only one CPU board is required.
Q: What can the bare minimum systems do?
A: Actually quite a lot, thanks to all the available software on the net. If you want to re-live the early days of the microcomputer revolution, there is plenty of RAM on either CPU board to load up Tiny BASICs, play games, write assembly language code, etc.
Q: How about mass storage?
A: We use our SD Card System. Our CPU boards include the low-level code providing drivers for the SD system, along with monitor commands to boot an operating system.
Q: What OS do you provide?
A: For the 6800, we use FLEX. For the 6809 we use FLEX/9 but have talked to various groups about multi-tasking operating systems. A different (still not released) I/O board is being developed to add additional capabilities for some OSes.
Q: An OS is great, but is there any software for those old systems?
A: Absolutely! Try looking at the FLEX User Group site: www.flexusergroup.com. They also have a large FTP site with a bunch of disk images. Drop those DSK files onto the SD card, mount the file as a disk drive, and you’ve got the disk contents for your use.
Q: So what do you guys do with YOUR systems?
A: I’ve got both 6800 and 6809 systems on the bench, both of which run FLEX, and are both a lot of fun to just program. I enjoy assembly language programming, so I’ve been working on some better tools for writing code.
Q: This stuff is all old technology, so shouldn’t it be cheap?
A: Sorry, this has a long answer. Some vintage parts are getting harder to find, demanding higher prices, or available in small quantities which have higher shipping costs. Some of these parts haven’t been manufactured since the early 1980s. Another big cost factor is that a lot of parts are needed, so while a more modern part might cost a few dollars more, the “more vintage” design sometimes requires several dozen of the older technology devices. Yet another factor is that the cost of printed circuit boards is based on the size of the board and the number being ordered. Ordering a single board might have a $70 set-up fee, and then $50 for the single board. Bumping up to 30 boards still has the $70 set-up fee, but the per-board cost might drop to $10. Given the size of the boards and the fact that each board has only limited functionality (as per the original design), the fixed prices are fairly high.
Q: What else is needed, really?
A: Just a terminal and an RS-232 cable OR a personal computer with a serial port, cable, and a terminal emulator program. At shows we always use Wyse 30 terminals as they are available nicely refurbished for about $200.
Q: If I buy one, how hard is it to get running?
A: Before we ship a complete system, everything is plugged in, the system is brought up, then it is disassembled, packaged, and shipped. It’s really quite simple to plug in the boards and get running. Our suggestion is to set up just the motherboard, power supply, CPU board and serial board. Once your terminal is talking to the system, then it’s easy to plug in the parallel card, connect the SD card system, and boot into FLEX.
Q: Can I use Corsham Tech boards in a real SWTPC system or use SWTPC boards in a Corsham Tech system?
A: Absolutely! I sometimes bring several real SWTPC boards to demos, but they tend to draw a lot of current. Their 8K RAM board draws more than our complete 6809 system with a meg of RAM.
Q: Is there a case to put a system in?
A: Unfortunately, no. We’ve looked at getting cases made but the price is always more than customers would be willing to pay. Some customers have built their own cases and I’ve played with a few designs. If you happen to work for a company that makes enclosures and have ideas, please contact me!