SBC6120/FP6120 Buy 2013

From Spare Time Gizmos' Wiki

Revision as of 18:45, 28 January 2013

News, Updates and Status Reports

• Looking thru my inventory after the recent SBC6120-RC buy, I see that I have thirty tested, known good, HD6120 CPU chips left on hand and that's left me pondering the question of "what would be a good use for them?" Given that the last group buy for the original was held three years ago, that seems like the obvious candidate. After calling my old suppliers and asking for quotes, I'm convinced that it's still possible to get all the parts necessary to build the original SBC6120/FP6120 combination, including the fancy paddle switches and custom faceplate. --Gizmos 11:24, 26 January 2013 (PST)

What is it ?

The SBC6120 is a replica of a 1960s/70s vintage DEC PDP-8 computer. It uses the Harris HD6120 "PDP-8 on a chip" CPU and started off as a single board computer the size of a 5-1/4" hard disk (and hence the name, "SBC6120"). Everybody wanted a lights and switches front panel, and a couple of years later I designed the FP6120 ("Front Panel 6120") that you see in the photos. The SBC6120 is fully operational and functional without the front panel - this is handy when assembling the kit, because it's possible to assemble and test the SBC6120 before the front panel is finished. The reality is that no one ever wants one without the other, and so the SBC6120 and FP6120 are always sold together as a set.

The HD6120 CPU used in the SBC6120 is the same one used in Digital's DECmate "personal" computers and is fully software compatible with a PDP-8/E. The front panel is fully functional and has the same complement of lights and switches as a real PDP-8/E. It measures 15" by 8-1/2" and is about 3/4ths scale when compared to a real PDP-8. The SBC6120 will run most software written for a PDP-8, including DEC's OS/8 disk operating system. The SBC6120 has an IDE disk interface that can be used with a real drive or (more commonly these days) a CompactFlash card or SSD.

To find out more, read the manuals for the SBC6120 and the FP6120.

Why a group buy ?

Originally Spare Time Gizmos stocked and sold SBC6120 and FP6120 kits as regular items, and many hundreds were sold that way. However some of the parts used are custom made, such as the faceplate, which is laser cut and silk screened, or the LED shadow mask, which is CNC machined. Many other parts, for example the paddle switches, have to be special ordered from the manufacturer even though they are "stock". All these items have minimum order quantities and can only be purchased economically in large batches. As orders for the SBC6120/FP6120 dropped off, the cost of carrying these items in inventory became prohibitive and Spare Time Gizmos stopped stocking the SBC6120/FP6120. The only practical way to sell them now is in batches of at least 25 to 30 units. Several such group buys have been done in the past, and this will be the fourth one.

What do I get ?

The purpose of the group buy is to batch up all the "unobtainium" parts that you simply cannot buy anywhere else. To that end, Spare Time Gizmos will supply a partial kit for the SBC6120 and FP6120 containing[1] -

• The beautiful FP6120 faceplate, silk screened in five colors and laser cut
• SBC6120 bare PC board (four layers, silk screened and solder masked)
• FP6120 bare PC board (two layers, silk screened and solder masked)
• One NOS HD6120 PDP-8 CPU chip
• A set of 20 paddle switches for the FP6120
• A custom machined LED shadow bar for the FP6120
• Three 64Kx4 SRAMs
• Two 27C256 EPROMs pre-programmed with BTS6120
• Five pre-programmed PLDs (three for the SBC6120 and two for the FP6120)
• Two stacking bus connectors used to connect the SBC6120 to the FP6120

That's all - the rest of the parts you will need to supply yourself. You should expect to spend another $100 to $200 for the remaining PCB mounted components, depending on how well stocked your parts box is. And of course that doesn't include an enclosure, terminal, disk drive or power supply. There is a complete parts list in the back of the SBC6120 and FP6120 manuals, and there are also some more current lists, complete with DigiKey and Mouser part numbers, in the files area of the Spare Time Gizmos Yahoo! Group.

How much does it cost ?

THE PRICE FOR THIS PARTIAL KIT OF PARTS WILL BE $600. Shipping and handling charges to US domestic addresses is $40 for USPS Priority mail with insurance. International shipping to addresses outside the US is $70, once again for Priority mail and insurance. All shipments to California addresses must also pay 8.625% CA sales tax.

How do I sign up ?

Send me an email and let me know where you live (so I can calculate the shipping and tax) I'll send you a Google Wallet invoice. Pay the invoice with your credit card and Google will place a temporary authorization against your card for the amount of the sale. This is not a charge and is simply to verify that your card is valid and your credit limit suffient to cover the charge. When I receive enough orders to make the group buy feasible, I'll place orders my my suppliers for the parts.

The lead time for the components is around two to three weeks, and it'll take me about a week to package up the kits after that. It's at this point that Google Wallet will charge your credit card. Depending on how long it takes us to reach critical mass, you can expect a four to six week delay between placing your order and your kit actually being shipped.

Remember that your credit card is not charged when you place the order. Your card will not be charged until your kit is actually shipped.

Where can I get more information ?

• Wondering what's going on? Check the Updates and News section at the top of this page.

• Have a question? Check the Group Buy FAQ first.

• There are web pages for both the SBC6120 and FP6120.

• There are full manuals, including assembly instructions and parts lists for the SBC6120 and the FP6120.

• Steve Gibson has some wonderful pages and videos that explain both the original PDP-8 as well as the SBC6120 specifically.

• There is a Yahoo! Group for builders of all Spare Time Gizmos kits. You can post your technical questions there. And be sure to browse the group archives too - there are lots of pictures and files related to past SBC6120 builds.

• And lastly you can email me directly for payment and shipping questions. Please don't email me for technical questions - post those to the Yahoo group so that we can all hear what's said and participate. If you haven't already joined this group then you should, and while you're there check out the group archives.