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SCELBI progress

Saturday, August 18th, 2012

Making progress on the SCELBI – I now have draft layouts of all 5 of the cards needed for a basic 8H system in CAD. Some are much closer to production ready than others, but they are all there. One interesting thing to note is that, so far, I haven’t found a single error in the SCELBI schematics that I’ve used as reference.

SCELBI card stack

I have also ordered enough 256×1 memories to populate 4 1K boards, so that I can build a full 4K 8H system. Turns out that American Microsemiconductor has 6000 MM1101A/A1 National parts with a date code 81 at 3.55 each. They are listed as 3-Input NAND-Function Logic Gate, but I’m convinced that that is a mistake. I hope I’m not wrong. Older Intel 1101s will easily cost over $10 each and you’ll need 32 of them for just a single 1K board. Ignoring the price, you may have trouble finding that kind of quanity.

American Microsemiconductor usually has high prices, but I’ve been able to find a couple of fairly good deals for RAM there. By the way, if you decide to order a bunch for yourself, be sure to talk to someone and ask for a quanity discount.

http://store.americanmicrosemiconductor.com/mm1101a-a1n.html

For the SCELBI, I’m going to be selling bare card sets, so you will need to find your own components, which is why I mentioning this opportunity. Since I haven’t built up a system with these parts, I can’t guarantee that they will work in the SCELBI.

By the way, I just recently figured out what the H stood for, in 8H. H stands for hobby. We knew that B stood for business, in the 8B system, but somehow it never dawned on me that H stood for hobby. So it seems that from the beginning that SCELBI had plans to create a range of machines. One of the great questions is what would have happened if Nat Wadsworth hadn’t suffered the heart attacks. Could SCELBI, with their vision and engineering skills been able to evolve and remain competitive?

Lastly, I hope to get together a SCELBI podcast in the next couple of weeks.

Posted in 8008, Vintage Computing | 1 Comment »

SCELBI memory

Friday, August 10th, 2012

The SCELBI 8H uses 256×1 bit MOS RAMs.

Doing the math, it would take 134,217,728, 256×1 bit chips to equal the memory capacity of a modern 4 Gigabyte memory module. I don’t know production figures, but I strongly suspect that adding all the 256×1 bit memory chips ever made together into one system, would not equal the memory capacity of a single modern 4 Gigabyte module.

Posted in 8008, Misc Stuff, Vintage Computing | 3 Comments »

SUPERPROTO Update

Friday, August 3rd, 2012

Check out the new light detector experiment that I just posted on the SUPERPROTO wiki. http://willegal.net/superproto/index.php?title=Photo_Detector It actually took me about 3 times longer to write up this new wiki page, as it took me to try this experiment out. The SUPERPROTO is really going to make experimenting on the Apple II a snap.

Thanks to Ken Gagne, I managed to sell a number of SUPERPROTOs at K’Fest. I also sold another to a person I know well. I expect to get some feedback with the next couple weeks, as well as get the few that did not sell at K’Fest returned to me. Assuming the feedback doesn’t reveal anything serious wrong with the design, I’ll be opening up general sales in about 2 weeks.

Regular price is still to be set, but will not be lower than the special K’Fest introductory price of $60. I know that this is quite a bit for a “proto” board, but the PCB and chip costs dictate price, and there is little I can do about it. However I will offer bare boards at approximately half the kit price, for those that can supply their own 75LS245, GAL, VIA and EEPROM, or don’t need them for their application. I’ll also consider quantity deals for folks that want a batch of bare boards to use as the basis for a limited production project. Drop me an email at mike@willegal.net if you have interest in a quantity deal.

Posted in A2 Proto Board, Apple II, Vintage Computing | Comments Closed

Lucky Me

Wednesday, August 1st, 2012

I never thought my interest in the early Apple Computers would result in this, but I have been mentioned or quoted in Make magazine, Computerworld and even a local edition of the Wall Street Journel

Now comes an awesome demonstration of a Mimeo by Evan Koblenz of MARCH at HOPE. This has just been published by the technology-related news website www.slashdot.org

Enough of the links – far more important to me than the press, is that I’ve become good friends with a wide range of super people with a similar interest in vintage computers. The people are the reason why I continue to invest so much time and energy in this hobby. Take away the people and I’m doing something else.

Posted in Apple 1, Vintage Computing | 1 Comment »

Significant Updates to SUPERPROTO wiki

Saturday, July 14th, 2012

The reference section has been significantly improved with following topics added:

Power and Ground Planes

Prototype Area for ICs

General Purpose Prototype Areas

Apple II Bus Access

Extending to a Bread Board for rapid prototyping

I’m particularly excited about the breadboard section, as it opens up the Apple II to easy HW prototyping.

SUPERPROTO connected to breadboard

A couple of years ago, James LittleJohn had offered a card (LittleProto II) with a breadboard built onto it. I think that the approach of a separate breadboard will allow you to easily work on your design, then when you feel that it is solid, move it permanently to the proto area on the card itself. In fact, Jon Titus had published a book back in the old days, that suggested a similar scheme for hardware interfacing. The book is called “Apple II Interfacing”. I talked to Jon about updating and releasing a modified version of this book a few months back, but at this point that project is in limbo.

Posted in A2 Proto Board, Apple II, Misc Stuff, Vintage Computing | Comments Closed

SUPERPROTOs will be at K’Fest

Thursday, July 12th, 2012

I sent 10 kits to the show – they will be priced at $60 each. One additional kit has been donated to the organizers as a prize/giveaway.

Here is what the built up superproto looks like.

SUPERPROTO

More information is available on the SUPERPROTO wiki. This is currently a work in progress, as there are several areas that need more documentation. In particular is a description of how the copper layer in the proto areas is set up. It is kind of hard to see, since the solder mask tends to conceal the connections between the pads.

I also need to add a page to show how to connect the SUPERPROTO to a separate breadboard for easy prototyping.

More kits will be available in a few weeks, once I catch up on things.

After the grounding issue with the Brain Board, I did as much research on grounding Apple II plug in cards, as I could. This included rereading some Apple Tech Notes on the topic, which were somewhat insightful, as well as examining existing designs.

I really tried extra hard to make the ground plane on this board as good as I could make it, and still keep the 2 layer layout. The result exceeds my expectations, as the ground noise on the base SUPERPROTO card is almost non-existent. The 5 volt supply also received some attention, and it looks clean as well. In fact, the board looks much cleaner than my wire wrapped prototype, so I must have done something right.

Posted in A2 Proto Board, Apple II, Vintage Computing | 1 Comment »

Mimeo update

Tuesday, July 3rd, 2012

If you are on my waiting list for Mimeo kits, I should be contacting you in the next few days about PCBs. If you have been waiting for more than a month or two, feel free to remind me about your interest. PCBs will go first to those that have been on the waiting list the longest. The folks at Unicorn Electronics believe that they will have parts kits available as soon as next week. If you are waiting for assembled systems you will have to wait a while longer. I’m planning on doing enclosures this time and everything will take considerable time and effort to put together. I’m up to my ears in ongoing stuff, right now.

New pricing and basic ordering information is posted on my Mimeo page:

http://www.willegal.net/appleii/apple1-kit.htm

Reminder – I will be supplying only PCBs (motherboard and monitor PROMs) – other parts for a complete motherboard kit should be obtained from Unicorn Electronics.

For the smaller kits, like the Brain Board, ACI and PS/2 adapter, I’m still supplying the entire kit.

Posted in Apple 1, Vintage Computing | 1 Comment »

Great Mimeo Kit News – Kits available soon

Wednesday, June 20th, 2012

PCBS

The batch of boards I purchased last month were all sold as bare boards, so I’m getting a new batch made up. More than half of those boards went to a company in Los Angeles which turned them into non-functional props for the new Steve Jobs movie starring Aston Kutcher. I’m expecting that that movie will feature some cool looking props, when it comes out.

Anyway the new batch of PCBs will take a couple of weeks to arrive.

Kits

I’m excited to announce that there will be some changes for those of you that wish to purchase Mimeo kits. I’ll be selling boards to you and parts kits will be purchased directly from Unicorn Electronics. I’ve sent BOM information to Rob at Unicorn, who is working hard to get all the required parts. Rob tells me that he has most parts on hand, already, but there are a few more to gather. I am really excited about this arrangement, as it should greatly increase the availability of Mimeo’s to the vintage computer hobbyist and free up time for me to work on new projects – a win for everyone. People wanting to build kits would have to take a couple of extra steps to get their kits. I think that this is a small price to pay for increased availability.

Mimeo Assembly Manuals
For hard copy assembly manuals, I’ll probably make it a separate, extra cost option, though I’m also considering using a print on demand service, so you would have to order the manual separately.

Assembled Mimeos
For those of you who want a built up Mimeo, I’m looking into building a few complete systems, with keyboard, enclosure and cassette player. Be forewarned, this sort of system will take a lot of time and money to put together. I haven’t set a price, but the number I have in mind will put it into the luxury item category.

Apple II rev 0 PCBS?
Ordering and putting together kits for Mimeo has been a huge time sink, and this change will allow me more time to work on new projects. If it works out well, I’ll also seriously consider making a new run of Apple II rev 0, reproduction motherboards. Unicorn would become the default parts supplier for that kit, as well.

Simpler Kits
For simpler kits, like the ACI, PS/2 adapter and Brainboard, I will continue to supply the complete kit, just like before.

Posted in Apple 1, Apple II, Vintage Computing | 2 Comments »

Vince Briel evaluating doing a cassette interface card

Tuesday, June 19th, 2012

Check out the post on his forum. I think all replica 1 owners should get a cassette interface for their units. Using an ACI is pretty essential to a faithful Apple 1 experience. Back in the the old days, it was…

the only Apple 1 expansion card ever offered by Apple.

the only way to share software between Apple 1 owners

Owners of original Apple 1’s or clones like my Mimeo or the Obtronix understand that without a Cassette interface, an Apple 1 Computer is nearly useless.

Cassette interface technology can be challenging. Note that Vince’s unit is most likely to incorporate several design features that I first documented either on my web site, or on Applefritter.

input coupling cap change to .1UF- see my ACI page

referencing voltage comparator to ground instead of -12 volts: see the applefritter post

If you can’t wait for Vince to make an ACI board, I have authentic reproducion ACI kits in stock and ready to ship for $75. Drop me an email at mike@willegal.net

Posted in Apple 1, Vintage Computing | Comments Closed

8008 Performance

Monday, June 18th, 2012

To evaluate real world 8008 performance, I have done some performance measurements using SCELBAL in my 8008 emulator. The 8008 running a typical BASIC program, such as “99 bottles of beer on the wall”, executes around 32,000 instructions per second. That is .032 MIPS, for those of you that measure processor performance that way. In contrast, the 6502 is said to execute roughly 300,000 instructions per second. However that is not the whole story, as instruction set influcences performance of real world programs in a significant way. For example, a single memory access on the 8008 will require 3 instructions if the H and L registers are not set up in advance. The 6502 can access any memory location in the entire 64K address range with a single instruction, without any need for setting up registers in advance.

Running a typical instruction mix, the 500 KHZ 8008 processor executes instructions about 10 times slower than the later 1MHZ 6502 used in the Apple ][.

Posted in 8008, Vintage Computing | Comments Closed

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